Poorna’s

Geol-101: Physical Geology Telecourse

What is Physical Geology all about? Physical Geology examines the earth materials, processes, surface morphology, internal structure, evolution, resources and environment.

Visit http://cs.ndsu.nodak.edu/~slator/htm/PLANET to use “Geology Explorer: Planet Oit Information” being developed at the North Dakota State University

The subject-matter of these studies includes*

Earth and earth processes:

– The Earth’s Interior (Chapter 2) – The Sea Floor (Chapter 3) – Plate Tectonics (Chapter 4) – –

Mountain Belts and Continental Crust (Chapter 5) Geological Structures (Chapter 6)

Earth hazards, primary earth materials:

– Earthquakes (Chapter 7) – Time and geology (Chapter 8) – Atoms, Elements and Minerals (Chapter 9) – Volcanism and Extrusive Rocks (Chapter 10) – Intrusive Activity and Origin of Igneous Rocks (Chapter 11)

Secondary rocks and the related matters:

– Weathering and Soil (Chapter 12) – Mass wasting (Chapter 13) – Sediments and Sedimentary Rocks (Chapter 14) – Metamorphism, Metamorphic Rocks and Hydrothermal

Rocks (Chapter 15) Streams and Landscapes (Chapter 16)

Other surface processes, earth resources:

– Groundwater (Chapter 17) – Deserts and Wind Action (Chapter 18) – Glaciers and Glaciation (Chapter 19) – Waves, beaches and coasts (Chapter 20) – Geologic resources (Chapter 21)

*The chapter numbers here refer to those in the textbook: PHYSICAL GEOLOGY: EARTH REVEALED by David McGeary and Charles Plummer (WCB/McGraw-Hill, 1998). You can also explore the companion website of the book’s other version (you will need to match the chapter titles here, though, because the sequencing of chapters in the version presented online differs from your video-adapted version) at http://www.mhhe.com/earthsci/geology/plummer/student.mhtml

–

The current concerns in these studies include

the earth hazards like earthquakes and volcanism and the internal processes that govern them, the issues like global warming, environmental and/or evolutionary impacts of

catastrophic events, waste disposal, coastal habitat etc., and the earth resources and their potential exhaustibility.

1

The processes that shape the Earth Two processes — hydrological cycle and plate tectonics — continually shape and reshape the Earth

Earth, the “Third Rock from Sun”, is called the “Lonely Planet” because, to our knowledge as yet, earth is the only planet with the evidence of life. It is also called the “Blue Planet”, because water is abundant on Earth. Compositionally, three groups of elements form the major consti-tuents of Solar System: (a) the gaseous elements H and He (e.g., Sun, Jupiter and Saturn), (b) the ice-forming elements C, N and O that occur as solid NH3 (ammonia), CH4 (methane) and H2O (ice) (e.g., Uranus and Neptune), and (c) the rock-forming elements Mg, Fe and Si (e.g., the inner or terrestrial planets — Mercury, Venus, Earth, Mars — and the asteroids and Moon.

1090.380.971.000.53

11.219.363.703.520.17

EquatorialRadius

(Earth = 1)

SunMercury

VenusEarthMars

JupiterSaturn

UranusNeptune

Pluto

333×103

0.060.821.000.11

317.8995.1414.5217.46

0.10

Mass(Earth = 1)

140954104990551739401330706

170022602500?

Density(Kg/m3)

~240 Ma88

225365687

433310759306856019091000

Lengthof year(days)*

25.38§

59244†0.997

10.41§

0.430.45†0.636.39

Lengthof day(days)

…58

108150228778

1427287044975910

Distancefrom Sun(103 Km)

*excepting that for Sun §at equator, as the period varies with latitude †retrograde

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EquatorialRadius

(Earth = 1)

SunMercury

VenusEarthMars

JupiterSaturn

UranusNeptune

Pluto

333×103

0.060.821.000.11

317.8995.1414.5217.46

0.10

Mass(Earth = 1)

140954104990551739401330706

170022602500?

Density(Kg/m3)

~240 Ma88

225365687

433310759306856019091000

Lengthof year(days)*

25.38§

59244†0.997

10.41§

0.430.45†0.636.39

Lengthof day(days)

…58

108150228778

1427287044975910

Distancefrom Sun(103 Km)

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11.219.363.703.520.17

EquatorialRadius

(Earth = 1)

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11.219.363.703.520.17

EquatorialRadius

(Earth = 1)

SunMercury

VenusEarthMars

JupiterSaturn

UranusNeptune

Pluto

333×103

0.060.821.000.11

317.8995.1414.5217.46

0.10

Mass(Earth = 1)

333×103

0.060.821.000.11

317.8995.1414.5217.46

0.10

Mass(Earth = 1)

140954104990551739401330706

170022602500?

Density(Kg/m3)

140954104990551739401330706

170022602500?

Density(Kg/m3)

~240 Ma88

225365687

433310759306856019091000

Lengthof year(days)*

~240 Ma88

225365687

433310759306856019091000

Lengthof year(days)*

25.38§

59244†0.997

10.41§

0.430.45†0.636.39

Lengthof day(days)

25.38§

59244†0.997

10.41§

0.430.45†0.636.39

Lengthof day(days)

…58

108150228778

1427287044975910

Distancefrom Sun(103 Km)

…58

108150228778

1427287044975910

Distancefrom Sun(103 Km)

*excepting that for Sun §at equator, as the period varies with latitude †retrograde

Two reasons explain why water, which should occur all over the Solar System wherever the temperatures are between 0ºC and100ºC, is so abundant on Earth but a rarity elsewhere: (a) hydrological cycle and(b) plate tectonics. Here, hydrological cycle is the conti-nuous recycling of water between oceans, atmosphere and land. As the run-off from land eventually fills up the ocean basins and levels the land, hydrological cycle carries the seeds of its own destruction as the resulting smoothening of the surface eventually translates into the drying up of the Earth.

Evaporation320,000 km3

Ocean Storage1,370,000,000 km 3

Precipitation285,000 km3

Precipitation95,000 km3

Evaporation60,000 km3

Run-off: 35,000 km3

A conceptual look at the hydrological cycle

Evaporation320,000 km3

Ocean Storage1,370,000,000 km 3Ocean Storage1,370,000,000 km 3

Precipitation285,000 km3

Precipitation95,000 km3

Evaporation60,000 km3

Run-off: 35,000 km3

A conceptual look at the hydrological cycle

Plate tectonics, on the other hand, involves the creation of new surface area, in the form of ocean basins, so compensating for the surface area lost in folded mountain belts and deep sea

200 Ma (million years) ago

135 Ma ago

65 Ma ago

Present

Plate tectonics explains how the Earth’s surface morphology, including the

relative geography of landand oceans, has evolved

continually over thegeological time.200 Ma

(million years) ago

135 Ma ago

65 Ma ago

Present

Plate tectonics explains how the Earth’s surface morphology, including the

relative geography of landand oceans, has evolved

continually over thegeological time.

trenches. This explains why the ocean floor is made up of basalt, a volcanic rock. Obviously, the water on Earth would have long disappeared had plate tectonics not existed to

continually create the ocean basins that hydrological cycle would then fill up. Earth remains the water planet because (a) temperatures over most of the Earth’s surface are between 0ºC and 100ºC, (b) the temperature gradient in the troposphere is steep enough to allow the precipita-tion of atmospheric moisture, (c) the hydrological cycle has been perennially present, and (d) plate tectonism has occurred throughout, ever since the oceans evolved ~4 Ga ago.

2

Earth, Venus and Mars Water is abundant on the Earth, but not on Venus and Mars. This is because of their significantly different atmospheres and because of the presence or absence of plate tectonic activities.

Considering the vast distances in Solar System, Venus, Earth and Mars are in about the same vicinity relative to the Sun, compared to the Jovian and the outer planets. Venus is closer to Sun than Earth, of course, and Mars is farther. But the resulting difference in Solar heat input is not what makes the Venutian surface too hot, or the Martian surface too cold, to have water. Also, judging from their comparable overall densities, they have similar chemical compositions. Neither of these explain what makes Earth so unique in having the abundance of water that Venus and Mars lack.

Earth

Venus

Mars

Density(Earth = 1)

90.001.000.01

Compo-sition

C, ON, O

N, O ?

PlanetaryComposition

Rockywith metallic

core

Atmospheric

VenusEarthMars

Density(Earth = 1)

90.001.000.01

Density(Earth = 1)

90.001.000.01

Compo-sition

C, ON, O

N, O ?

Compo-sition

C, ON, O

N, O ?

PlanetaryComposition

Rockywith metallic

core

PlanetaryComposition

Rockywith metallic

core

Atmospheric

VenusEarthMars

The three planets have vastly dissimilar atmospheres. Earth’s atmosphere, a ~110 Km thick gaseous halo that encases the Earth, now comprises ~78% Nitrogen and ~21% Oxygen, but was nearly 90% CO2 until about 1.25 Ga ago. The atmosphere of Venus has 90 times the density of Earth’s atmosphere, and is ~95% CO2. Since this traps the Solar heat that is received on that planet’s surface, Venus is also called the “Greenhouse Planet”. Mars, on the other hand, has a very thin atmosphere.

Another major peculiarity of Venus is that its average day-time temperature is about the same (~450ºC) as its mean night-time temperature. This is because the lengths of day and year are about the same on Venus, i.e., the planet takes about the same time to complete one spin on its axis as it does to complete one orbit about the Sun and therefore has the same face turned to-wards Sun all the time. The planet’s thick atmosphere retains and distributes evenly this Solar heat that one side of the planet thus receives constantly, so producing the intense temperatures that preclude any possibility for even the water molecule to exist. This renders moot any question of hydrological cycle on Venus. As for Mars, there is good evidence that water was

Some images of the Martian surface, as obtained by the Pathfinder and sub-sequent missions.

Some images of the Martian surface, as obtained by the Pathfinder and sub-sequent missions.

once abundant enough on the planet to have produced the land-forms we now see but now remains confined to the subsoil and the polar ice cap. The question, then, is as to how might Mars have lost its hydrologi-cal cycle.

Some images of the Martian surface, as obtained by the Pathfinder and sub-sequent missions.

Some images of the Martian surface, as obtained by the Pathfinder and sub-sequent missions.

once abundant enough on the planet to have produced the land-forms we now see but now remains confined to the subsoil and the polar ice cap. The question, then, is as to how might Mars have lost its hydrologi-cal cycle.

NASA’s 2001 Mars Odysseyspacecraft provided this

view of the south poleof Mars in inter-mediate energy,

or epithermalneutrons. Soil

enriched inhydrogen isindicated by

the deep blue colors on themap, where a

low intensity ofepithermal neutrons

is found. This view ofthe south pole of Mars comes

from measurements made in the firstweek of Mars Odyssey’s mapping, in February 2002.

NASA’s 2001 Mars Odysseyspacecraft provided this

view of the south poleof Mars in inter-mediate energy,

or epithermalneutrons. Soil

enriched inhydrogen isindicated by

the deep blue colors on themap, where a

low intensity ofepithermal neutrons

is found. This view ofthe south pole of Mars comes

from measurements made in the firstweek of Mars Odyssey’s mapping, in February 2002.

0° 50°- 50°- 100°Temperature (°C)

Alti

tude

(Km

)

1

2

5

10

20

50

Tropopause

Troposphere

Strato-pause

0° 50°- 50°- 100°Temperature (°C)

Alti

tude

(Km

)

1

2

5

10

20

50

Tropopause

Troposphere

Strato-pause

This is because plate tectonics once occurred on Mars, but no longer does. Mars thus lacks hydrological cycle because it no longer has the plate tectonics to create new ocean basins to replace the ones flattened by the “run-off” component of hydrological cycle*. The presence of hydrological cycle on the Earth, and its absence on Mars, is therefore due as much to the planetary atmospheres as to plate tectonics, while its absence on Venus is entirely ascribable to the structure and composition of Venutian atmosphere.

Temperature profile of Earth’s troposphere

* Seeking to answer this question by appealing to low density of Martian atmosphere, and argue that its temperature gradient is too gentle to have prevented the escape of atmospheric moisture (unlike Earth’s tropospheric thermal gradient that is steep enough to have retained the hydrological cycle), ignores the fact that a vigorous hydrological cycle may have once existed on Mars.

3

A discussion of the earth’s interior is the basic prerequisite for understanding Earth’s Interior Physical Geology partly because of the role of planetary dynamics in creating and sustaining the planetary processes and partly because the tools that inform us of the planetary interior are also the ones we need in our understanding of the surface effects.

Access the USGS publication “Interior of the Earth” at http://pubs.usgs.gov/gip/interior

Earth is a multi-layered body — Crust is the earth's thin (0-70 Km) outer skin, averaging ~30 Km

beneath the continents and ~15 Km beneath the oceans. — Mantle is the earth's ~2,900 Km thick and rocky outer shell that

underlies the crust. — Core is the earth's ~3,500 Km thick metallic interior, comprising the

(a) solid inner core (1,250 Km radius), and (b) liquid outer core (2,250 Km thick).

(Inner core and crust have similar volumes of ~8.2×109 Km3)

Of the 9 elements that dominate the Earth's chemical composition,

OxygenSilicon

MagnesiumIron

AluminumCalcium

NickelSodium

PotassiumOthers

OSiMgFeAlCaNiNaK

29.8%15.6%13.9%33.3%1.5%1.8%2.0%0.2%

1.9%

46.6%27.7%2.1%5.0%8.1%3.6%

2.8%2.6%1.5%

WholeEarth

Earth’sCrust

OxygenSilicon

MagnesiumIron

AluminumCalcium

NickelSodium

PotassiumOthers

OSiMgFeAlCaNiNaK

29.8%15.6%13.9%33.3%1.5%1.8%2.0%0.2%

1.9%

46.6%27.7%2.1%5.0%8.1%3.6%

2.8%2.6%1.5%

WholeEarth

Earth’sCrust

— crust carries most of the Earth's Si, O, Al, Ca and Na;

— mantle is, in effect, a compositional replica of the whole earth; whereas

— most of the earth's Fe, Mg and Ni occur in the core.

Information on the Earth's internal structure comes from (a) gravity, (b) seismic, and (c) geomagnetic studies. The Gravity Picture

— Because of earth’s equatorial bulge and polar flattening, gravitational acceleration on the surface increases from equator to the poles.

— The whole earth density (~5.5 g/cm3) is about twice the average crustal density (~2.7 g/cm3): Clearly, density increases with depth.

— The continental crust is lighter and thicker than the oceanic crust, as “mountains have their own roots” (i.e., isostasy).

The undulations of the geoid, or the equipoten-tial surface, reveal inhomogeneous mass distribution. For instance, notice in this picture of the earth geoid from NASA how the geoid is depressed in South Asia-Indian Ocean and North America regions, and is raised in the North Atlantic and West Pacific regions and in the region immediately south of Africa.

The Seismic Evidence — Seismic waves are of two types: the surface waves (Love and

Rayleigh) and the body waves (the P and S waves). Of these, P-wave velocity in the crust averages ~6 Km/s, S-wave ~4 Km/s.

— Earthquake focal depths are usually <250 Km. — The “shadow zone”: No direct P-waves from an earthquake.

arrive between 103° and 142° from the epicenter, whereas no direct S-waves from an earthquake are seen beyond 103° from the epicenter. Since S-waves do not traverse a fluid layer, where the P-waves slow down, this suggests that the outer core is a fluid layer.

The Geomagnetic Field — Earth has a magnetic field that behaves as if there is a

bar magnet inside the earth and along the spin axis. This time- averaged geomagnetic field is a geocentric- axial-dipole.

— Crustal magnetization is too weak to produce this magnetic field and the sub-crustal region is too hot to be magnetic. The magnetohydrodynamics of the fluid and metallic, and therefore electrically conducting, Outer Core offers the most acceptable self-sustaining and regenerating mechanism that we need to explain the origin of the geomagnetic field. National Geophysical Data Center at

To learn about the ghttp://www.ngdc.noa

G.B. Airy'sillustrated hdensity crustratum. Thmountain (ocean) is: R = (h×σcr

Here h is hmean sea are densitrespective

This is NASA’s picture of the earth geoid (http://ekman.unh.edu/course/intropo/GRAPHICS/Geoid.

4

Isostasy 1855 model of “isostacy”, ere, assumed that the low st floats over a denser sub-e root ‘R’ of crust beneath a

or its antiroot beneath an

ust)/(σcrust – σsubcrust)

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eomagnetic field, visit the a.gov/seg/potfld/geomag.shtml

level while σcrust and σsubcrust ies of crust and subcrust ly.

gif)

The Sea Floor

The Oceans cover ~72% of the earth’s surface;

have an average depth of ~3.8 Km,

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Continentalmountains

Geology of the Sea-Floor

http://pubs.usgs.gov/pdf/planet.pdf

Visit the US Geological Survey at http://pubs.usgs.gov/pdf/planet.pdf or the Marine Geology and Geophysics Division of National Oceanic &

Atmospheric Administration’s (NOAA) National Geophysics Data Center (NGDC) at the URL: http://ngdc.noaa.gov/mgg/mggd.html

compared to ~840 m average height of the continents; and comprise <200 Ma old basaltic floor; but were plausibly created ~3.7 Ga ago;

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Physiography of the Sea Floor Ocean floor comprises (a) continental margins and (b) deep ocean basins. Continental margins (a) can be active (i.e., seismic) or passive (i.e., aseismic); (b) comprise ~14% of ocean area, with ~750 m average depth; and (c) carry ~52% of all sediments (thickness: <7 Km). Deep ocean basins (a) cover ~85% of the ocean surface and (b) comprise (i) abyssal seafloor (~80% of ocean area, ~4.5 Km average depth, ~13% of all sediments averaging ~200 m in thickness); (ii) ridges and rises (e.g., the Mid-Atlantic Ridge, East Pacific Rise etc.): ~6% of ocean area, ~2.5 Km average depth, ~28% of world’s sediments (thickness ~8 Km); and (iii) deep sea trenches and island arcs: ~1% of ocean area, ~6.5 Km average depth, ~1% (?) of all sediments.

Bathymetric, magnetic and stratigraphic profiles across the submarine ridges and rises tend to be symmetric. Ridge axes have

the youngest rocks, high heat flow and seismicity. Interpretation of

these magnetic anomaly profiles using the Vine and Matthews model yields the map of seafloor ages.

This Postulate of Sea-Floor Spread ascribes the forming of new ocean floor to continental rifting and incessant volcanism at the rifted margins — a process that creates spreading submarine ridges and rises.

Deep sea trenches form, on this picture, when the converging sea floor edges collide.The other notable features of the sea floor include aseismic rises, seamounts, guyots, and submarine canyons.

5

Global Plate Tectonics The “plate tectonics” postulate — unifies the earlier hypotheses of continental drift, sea-floor

spread and mountain building into a single theme, and — ascribes the evolution of earth’s surface morphology to

relative angular motions of rigid lithospheric plates, litho-sphere being the Earth’s ~150 km thick rigid outermost shell that includes the entire crust and the top part of the mantle.

The basic tenets Go to this website to read this USGS online publication

http://pubs.usgs.gov/publications/text/dynamic.html

— Present ocean floor covers ~70% of earth’s surface, and is <200 Ma old compared to up to >4 Ga age of continental rocks, but earth has not expanded appreciably during the past ~200 Ma.

— This is because every creation of new surface area as an ocean floor is balanced by the loss of an equal surface area elsewhere (e.g., in a folded mountain belt or a deep sea trench).

The map on the left shows the principal plates of the world.

The map on the top right shows

the distribution of spreading subma-

rine ridges and the bottom map

shows the distribution of

deep-sea trenches.

New data suggest that Earth’s largest plate, the Pacific plate, moved about 1500 km northward over a 26 Ma period from Late Cretaceous to the late Eocene and another 500 km northward over a 39 Ma period since then (http://www.agu.org/sci_soc/action.html)

The plate boundaries The boundaries of lithospheric (i.e., the crust and the uppermost mantle) plates are essentially “seismic” and can be active or passive. — Active plate boundaries are where lithosphere

surface area changes, i.e., the surface is either created, at the divergent or accreting boundaries

(the spreading submarine ridges, e.g., Mid- Atlantic Ridge, East Pacific Rise etc.)

or destroyed, at the convergent or consuming boundaries (deep-sea trenches, e.g., Mariana trench, folded mountain belts, e.g., Alps and Himalayas, and at trench-mountain pairs, e.g., Peru-Chile trench and the Andes etc.

— Passive plate boundaries are where lithosphere (or new surface) is neither created nor lost, e.g., San Andreas Fault.

Mantle convection offers a plausible mechanism for plate motions.

Plate tectonics postulate explains the Pacific “Ring of Fire” and the reason why earth-quakes are so common in the deep sea trenches, folded mountain belts and similar tectonically active regions

6

Mountain Belts and the Continental Crust World’s major mountain ranges (below) were created by convergent tecto-nics. A ~400 Ma old North America-Africa collision probably created the Appalachians for instance, much like the way Himala-yas, now the world’s tallest mountains, formed 55-70 Ma ago when the northerly moving Indian plate colli-ded with rest of Eurasia. Shown below is a view of the Northern Teton Range in Rocky Mountains. Clicking on the picture will take you to the USGS/ National Park Service site that this picture is taken from. Try these virtual excursions The bottom right picture shows the Nanga Parbat range of Himalayas. Click on it to access the Uni-

The major mountain belts worldwide – are long and continuous chains that

comprise numerous mountain ranges or groups of closely spaced parallel to sub-parallel ridges (e.g., from the Aleutian Islands to Coastal Ranges and Rocky mountains in the North American Cordillera);

– often (though not necessarily always) tend to be

younger than the surrounding continental and/or oceanic regions, and

taller the younger they are; – usually comprise thick sedimentary

layers, mostly marine, compared to the thinner sedimentary cover of the rest of the continent;

– commonly have metamorphosed, often granitized, cores and intensely folded and faulted sections; and

versity of Leeds, U.K., site for a virtual excursion. Likewise, click on the left picture for a virtual trip to the Alps.

– overlie appreciably thicker crust than the average continent.

Folded mountain belts are believed to evolve in three main stages:

Himalayas display all these. Of the two Himalayan peaks shown on the right, the one on left is Mt. Annapurna. It is made up of limestones with ~200 Ma old Ammonites, suggesting that a deep ocean

– the accumulation stage creates a thick pile of mostly marine sediments and volcanics;

then existed here. The peak shown on the right is Mt. Everest, the world’s tallest peak. It is a gneissic dome. Gravity and seismic studies confirm Himalayan crustal thickness to be <70 km.

– the orogenic stage of intense deformation made up of folding accompanied with reverse and thrust faulting and followed by metamorphism and/or plutonic emplacements); and

– the uplift or block-faulting stage of “isostatic readjustment” and normal faults and block faulting.

Plate tectonics ascribes mountain building to convergent plate tecto-nics, which provide the necessary compressive forces in the orogenic stage, and thus distinguishes be-tween – the collision mountains like Alps, Himalayas

and Urals, which involve the convergence of continental edges of plates; and

– the cordilleran mountains like the Andes which involve convergence of the continental edge of one plate and the ocean edge of the other.

The Wilson Cycle, shown alongside, Continental Rifting(e.g., East African Rift)

Sea Floor Spread(e.g., Red Sea → Atlantic Ocean)

Convergence of the oceanic edges of two plates(Trench and Island Arc form, e.g., Mariana Trench and Philippines, Aleutian Trench and Aleutians)

Convergence of the oceanic edge of one plate and conti-nental edge of the other(Trench and folded mountain belt form, e.g., Filled Trench and North American Cordillera, Peru-Chile Trench and Andes)

Convergence of the continental edges of two plates(Folded mountain belt forms, e.g., Himalayas, Alps, Appalachians)

Weathering, ero-sion and peneplation(Flat cratonic topography of stable continental shields, e.g., the Mid-Continental Gravity High?)

Continental Rifting(e.g., East African Rift)

Sea Floor Spread(e.g., Red Sea → Atlantic Ocean)

Convergence of the oceanic edges of two plates(Trench and Island Arc form, e.g., Mariana Trench and Philippines, Aleutian Trench and Aleutians)

Convergence of the oceanic edge of one plate and conti-nental edge of the other(Trench and folded mountain belt form, e.g., Filled Trench and North American Cordillera, Peru-Chile Trench and Andes)

Convergence of the continental edges of two plates(Folded mountain belt forms, e.g., Himalayas, Alps, Appalachians)

Weathering, ero-sion and peneplation(Flat cratonic topography of stable continental shields, e.g., the Mid-Continental Gravity High?)

thus identifies mountain building as the closure of a process that begins with conti-nental rifting, so completing a cycle that lasts for 250-400 Ma or longer, judging from the example of the Appalachians that probably closed a >400 Ma old version of the present Atlantic ocean. Try http://csmres.jmu.edu/geollabs/Fichter/Wilson/Wilson.html for more on Wilson Cycle

Geological Structures are the strains or deformations that rocks undergo when subjected to different kinds of stress.

Stress and strain: – Stress can be

(a) compressive (or forcing shortening of space, as at the folded mountain belts), (b) tensional (stretching or elongation, as during sea floor spread), and (c) shear or transverse (e.g., transform faults, fracture zones, wrench or strike slip

faults) – Strain can be (a) plastic,

(b) elastic (e.g., postglacial rebound) or (c) brittle

Read this report on the geology of Sideling Hill Road Cut by David Brezinski (Maryland Geological Survey) at the URL:

– Based on the principle of original horizontality and the http://mgs.dnr.md.gov/esic/brochures/sideling.htmlMeasuring Strain law of superposition of strata (i.e., undeformed layers lie

horizontally and in stratigraphic order). – Strike and dip (or inclination) measure any departures from

horizontality. Folds: – Plastic deformation (i.e., rocks permanently bend under stress)

typically creates folds. – Anticlines (limbs inclined oppositely), synclines (limbs inclined towards one another),

isoclines (limbs inclined alike), recumbent (fold axis is horizontal) and monoclines

Strike and DipStrike and Dip

(only one limb inclined) are the common fold structures: they can be regional (anticlinorium and synclinorium) or local, and may plunge doubly as well. Open and overturned folds also occur.

Fractures, joints and faults: – Brittle strain (i.e., when strain rate is too great to be accomodated by

plastic strain) produces fractures, joints and faults.

Youngest

OldestFold

Ax

is Fold

Ax

is

Anticline Syncline

Youngest

Oldest

Youngest

OldestFold

Ax

isFo

ld

Axis Fo

ld

Axis

Fold

Ax

isFo

ld

Axis

Anticline Syncline

– Joints are fractures without displacements: (a) tensional stress tends to produce single joint sets perpendicular to the

direction of stress, (b) compressive stress usually produces two intersecting joint sets.

Normal Fault

Reverse Fault

Normal FaultNormal Fault

Reverse Fault

– Faults are defined by the direction of slippage:

(a) dip-slip faults have dominant slippage along the dip and can be normal (caused by tensional stress) and reverse (caused by compressive stress);

(b) strike-slip faults have dominant slippage along the strike and can be right-lateral (or dextral) and left-lateral (or sinistral)

Wasatch fault in Utah is a typical normal fault

Wasatch fault in Utah is a typical normal fault

The magnitude 6.4 Northridge earthquake (January 17, 1994) ruptured a reverse fault that resulted from compression.

The magnitude 6.4 Northridge earthquake (January 17, 1994) ruptured a reverse fault that resulted from compression.

(e.g., the San Andreas Fault, shown at the bottom right here, is a typical right-handed fault). Unconformities: – denote hiatus or break in

the geological succession that

– can be (a) disconformities, (b) angular unconfor-

mities or (c) nonconformities,

Grabens and Hosts are the exten-sional features that are produced by pairs of normal faults.

Graben or Rift Valley

Horst

Graben or Rift ValleyGraben or Rift Valley

HorstHorst

Try the URL: http://www.trinet.org/ for information on Southern California Seismicity. EarthquakesEarthquakes –

–

–

are vibrations caused by motions and/or deformation of earth’s rigid surface and can be therefore defined as the strains produced by accumulated stress; and result from sudden release of stored energy, with or without any visible extrusives, but can also result from landslides, nuclear blasts and bolide impacts.

Seismic waves are of two kinds body waves, comprising (a) the faster P (or primary)

Try http://wwwneic.cr.usgs.gov/ (USGS Earthquake homepage) and, for current California seismicity, try

http://pasadena.wr.usgs.gov/recenteqs/latest.htm

waves that move in alternate compressions and dilations and (b) the slower S (shear or second-dary) waves in which particles move transverse to the direction of wave propagation, that have enabled mapping the earth’s internal structure; and

– surface waves, comprising (a) Love waves (transverse, on the horizontal plane) and (b) Rayleigh waves (the backward rotating and circularly moving rolling waves).

Individual earthquakes – –

are described in terms of epicenter, focal depth and energy release; locating the epicenter requires the S and P-wave travel time difference from three stations;

This USGS Online Publication: EARTHQUAKES by Kaye M. Shedlock & Louis C. Pakiser is available at the URL: http://pubs.usgs.gov/gip/earthq1/ For earthquake related links on the web, try: http://www.whfreeman.com/bolt/ http://earthquake.usgs.gov/4kids/learning/exp.html

The above digital fault and fold map for Southern California is available at the URL: http://pubs.usgs.gov/of/1996/ofr-96-0263/geoset.htm It highlights blind thrust systems and other principal faults that the Southern California seismicity is typically associated with.

Richter magnitude, a logarithmic scale, is used to define the energy released by an earthquake (seismic moment* scale is a variant of it); Earthquake-proof construction takes ground-acceleration into account. Mercalli scale qualitatively measures earthquake intensity or the damage caused.

Earthquake occurrence, frequency and energy release Shallow focus earthquakes are most frequent and release most energy Minor earthquakes are ~1,000 times as common as the major ones but release ~10,000 times less energy

Shallow focusIntermediate focus

Deep focus

Focal depth0-70 Km

70-350 Km350-700 Km

% of allenergyreleased

8512

3

MagnitudeFrequency

Energy released

Minor4-5

~10,000/yr~1019 ergs/yr

Major7-8

~10/yr~1023 ergs/yr

Internally triggered seismicity and volcanic earthquakes: (a) tectonic earthquakes occur: (i) at the present and past plate boundaries and (ii) in the plate interiors (i.e., Stable Continental Region or SCR seismicity), and (b) volcanic earthquakes include hot-spot and subduction-zone seismicity, in addition to that at the mid-ocean ridges.

– Externally triggered seismicity includes collapse earthquakes, nuclear tests, and reservoir-induced seismicity.

Earthquake prediction: – –

The precursor signatures or the geophysical approach; The “Gap” theory or the statistical approach

Mercalli intensity vs. Richter Magnitude

Richter Magnitude

Mer

calli

Inte

nsity

Mercalli intensity vs. Richter Magnitude

Richter Magnitude

Mer

calli

Inte

nsity

How predictable are the earthquakes, really? Read USGS Factsheet “Quake Forecasting” at the URL: http://quake.wr.usgs.gov/prepare/factsheets/QuakeForecasts/

As Mercalli intensities show a wider spread over Richter magnitudes, a good disaster mitigation strategy for earth-quakes would be to lower Mercalli intensity of an event.

– – –

– – –

*Mw = log10 (M0) - 10.7; where M0 = shear strength of rock × rupture area of fault × average slip on the fault.

7

Earthquakes and Plate Tectonics Earthquakes and Plate Tectonics: –

–

Plate boundaries, whether active (i.e., divergent or convergent) or passive (i.e., transform faults), are essentially seismic. Seismicity at the divergent plate boundaries or spreading submarine ridges and rises tends to be (a) shallow-focussed, (b) low magnitude and (c) less common than at the convergent plate boundaries and transform faults.

– Seismicity at the convergent plate boundaries: Collision-zones or folded mountain belts:

(i) have frequent killer earthquakes, usually of intermediate focal depths but high magnitudes, that For the above data on worldwide seismicity, try:(ii) in terms of damage and devastation, are among the world’s greatest earthquakes

http://neic.usgs.gov/neis/general/seismicity/world.html

(e.g., based on their frequency during this millennium, Indosinian/Yenshan and Himalayan orogenies are associated with one >7 magnitude earthquake every 155+107 years).

Subduction-zones or deep sea trenches : (i) have frequent, deep-focus and high magnitude seismicity, and (ii) are common in the circum- Pacific region, have associated volcanism and/or folded mountain belts on the continental edges, and also often produce tsunamis.

– Seismicity at the passive plate boundaries: Shallow focus and

Divergent(Mid-Ocean Ridge)

ConvergentDeep Sea Trench —

Folded Mountain Belt —

Passive(Transform Faults,

Fracture Zones)

Magni-tude

Fre-quency

FocalDepth

Low

HighHigh

Intermediateto High

High

HighHigh

Low

Shallow

DeepModerate

Shallow toModerate

PlateBoundary

Divergent(Mid-Ocean Ridge)

ConvergentDeep Sea Trench —

Folded Mountain Belt —

Passive(Transform Faults,

Fracture Zones)

Divergent(Mid-Ocean Ridge)

ConvergentDeep Sea Trench —

Folded Mountain Belt —

Passive(Transform Faults,

Fracture Zones)

Magni-tude

Fre-quency

FocalDepth

Low

HighHigh

Intermediateto High

Low

HighHigh

Intermediateto High

High

HighHigh

Low

High

HighHigh

Low

Shallow

DeepModerate

Shallow toModerate

Shallow

DeepModerate

Shallow toModerate

PlateBoundary

moderate to high magnitude seismicity is common at the transform fault boundaries like the San Andreas and Dead Sea faults. The Dead Sea fault zone has already experienced one 6.3-

Plate tectonics and seismicity in Eastern North America Compared to the vibrant tectonics of western North America, the Atlantic continental margin is non-tectonic. Using plate tectonics, seismicity there can be explained as follows: The 7.3-7.9 magnitude 1811-12

New Madrid earthquakes can be ascribed to the paleosuture line seen as the Mid-Continental gravity high. The 6.7-7 magnitude Charleston

earthquake of 1886 occurred at the extension of Atlantic fracture zones into the continent. The rest of the seismicity here is

related to the Appachians folded mountain chain.

7.2 earthquake every 145+82 years through the millenium, for instance. Earthquakes in Western North America – –

Seismicity in western North America is mostly associated with plate tectonism. Plate tectonism and western North America: As North America moved westwards, with the opening of the North

Atlantic, it collided against and overran the plate east of the East Pacific Rise. This raised the basin and Range Province and created a subduction zone of folded mountain belt (the Cascade Ranges) and volcanism (from Mammoth Lake Caldera to Mt. Shasta, Mt. St. Helens and Mt. Rainer).

North America’s overrunning of Pacific Ocean spreading center (i.e., East Pacific Rise) (a) split Baja California from Mainland Mexico, in the South, and (b) created a transform fault (the San Andreas Fault) that now

runs through most of California. During this motion, North American plate twisted counterclockwise against the Pacific plate and traversed over a “Mantle Hotspot” or thermal plume that is now centered beneath the Old Faithful Geyser, Yellowstone National Park. The result is an east-west running chain of volcanics, from Yellowstone and Snake river in the east (current) to Columbia River Basalts in the west (< 15 Ma ago).

– The associated seismicity: • Subduction Zone Seismicity mostly characterizes Alaska where it is associated with the Aleutian trench (i.e.,

subduction of the pacific plate beneath North America — note that Alaska itself has joined North America in the geologically recent past).

• Spreading Center Seismicity is seen in the Salton Sea, Coachella Valley and Imperial Valley regions. • Transform Fault Seismicity characterized most of California, e.g., along the San Andreas Fault.

— the entire east-west trending belt from Yellowstone to the Columbia River basin and

Hotspot or volcanism related seismicity characterizes — the volcanic belt from Mammoth Lake to Alaska

Got questions? Ask Poorna Pal: poornapal@hotmail.com

8

Geological Time and the Evolution of Life HolocenePleistocenePlioceneMioceneOligoceneEocenePaleocene

Quaternary

Neogene

Paleogene

Phan

eroz

oic

Terti

ary

Cen

ozoi

c

CretaceousJurassicTriassicPermian

PennsylvanianMississippian

DevonianSilurianOrdovicianCambrian

Mes

ozoi

c

Carb

oni-

fero

us

Pale

ozoi

cP

rote

rozo

icAz

oic

orA

rche

an

Pre

cam

bria

n

4 Ga

1.2

1.9

2.5

5

5 Ga

Ga

Ga

144 Ma

208 Ma

245 Ma290 Ma323 Ma360 Ma408 Ma438 Ma505 Ma570 Ma

0 Ma0.1 Ma1.8 Ma

5 Ma23 Ma35 Ma57 Ma65 Ma

Late

Middle

Early

http:/www.ucmp.berkeley.edu/help/timeform.html

Life and the Geological Scale of Time It is not clear whether life intrinsically evolved on the earth or, having originated elsewhere, proliferated on the earth after the first oceans appeared ~4 Ga ago. Based on the earliest evidence of life, the 3.7-4 Ga old stromatolites, the first 500-1000 Ma of earth’s history appears to have been altogether barren. Based on the fossil evidence, the geological time is divided into –

–

the Phanerozoic (0-570 Ma) eon with a systematic record of life and comprises (a) Paleozoic (245-570 Ma), (b) Mesozoic (65-245 Ma) and (c) Cenozoic (0-65 Ma) eras of early, middle and modern life forms, respectively; and the Precambrian (570-4500 Ma), comprising (a) Archean (2.5-4.5 Ga) and (b) Proterozoic (570-2500 Ma) eons of little or no life and primitive life, respectively.

A stromatolite is a succession of thickened, domed-up layers produced by the colonies of cya-nobacteria. Living strom-atolites in Shark Bay, Australia are similar to those found in the 1.3 Ga old Siyeh Formation, Canadian Rockies, shown here.

To learn about different geological eras, periods and epochs, visit Univer-sity of California (Berkeley) Museum of

Paleontology's excellent Web Geological Time Machine at the URL:

Gradualism, Punctuated Equilibrium and Mass Extinctions: – Evolution of life over the geological times has followed three strands: (a) evolution of new

species, e.g., the end-Permian appearance of dinosaurs and mammals, (b) extinction of some existing species (e.g., the end-Cretaceous extinction of dinosaurs), and (c) proliferation of some existing species (e.g., the Cenozoic domination of mammals).

― Darwinian evolutionary model sought gradual morphological changes, leading to the evolution of new species, as would result from adaptation to the environmental change. But, com-pared to this ‘gradualism’, the observed fossil record displays sudden appearance of new species following periods of pro-longed morphological statis. The Eldredge-Gould model of ‘punctuated equilibrium’ (i.e., new species appear suddenly when, under environmental stress, portions of the gene pool of some existing species undergo rapid speciation) overcomes this problem. See, for instance, “Punctuated Equilibrium at Twenty: A Paleontological Perspective” by Donald

Tim

e (m

illio

n ye

ars)

Morphological ChangeMorphological Change

Gradualmorphologicalchange

Littlemorphologicalchange

Speciation

Rapidmorphologicalchange duringspeciation

Gradualism Punctuated Equilibrium

Prothero (Skeptic vol. 1, no. 3, Fall 1992, pp. 38-47): http://www.skeptic.com/01.3.prothero-punc-eq.htmland “Score One for Punk Eek: The fitful evolution of bacteria supports a controversial theory” by John Horgan (Scientific American, July 21, 1996): http://www.sciam.com/article.cfm?chanID=sa004&articleID=000DFABC-A1BF-1C76-9B81809EC588EF21

Perm

ian

Tert

iary

Tria

ssic

Jura

ssic

Cre

tace

ous

Silu

rian

Dev

onia

n

Car

boni

-fe

rous

Cam

bria

n

Ord

ovic

ian

0 300200100 500 Ma ago400

80

40

0

120

160

Extin

ctio

n R

ate

(Gen

era

per M

a)

Tertiary

Tertiary

Creta

ceous

Creta

ceous

~65 Ma cla

y

– Instances of mass extinction events too exist. Take the end-Cretaceous dinosaur extinction, ~65 Ma ago. That was also when 75% of the species disappeared and, at the end of the Paleozoic, ~245 Ma ago, an estimated 90% of all the species became extinct. Indeed, as the graph alongside shows, such events have recurred with a 25-30 Ma cyclicity that matches those in the records of bolide impacts as also volcanism. Hence the controversy about extraterrestrial catastrophism versus terrestrial cataclysms as the source of the environmental trauma that triggered these extinction events. In the case of dinosaur extinction ~65 Ma ago, the candidate extraterrestrial catastrophe is believed to be the bolide impact and the likely candidate for terrestrial catastrophism is Deccan flood basalts, India.

Pictured on the left is the thin K/T boundary clay in Gubbio, Italy, whose high iridium content first pointed to an extra-terrestrial source.

9

ATOMS, ELEMENTS AND MINERALS

Atoms and Elements Browse the “Periodic Table of Elements” page at Los Alamos National Laboratory (http://pearl1.lanl.gov/periodic/default.htm)

An element is the simplest form to which the matter can be reduced by ordinary chemical methods, e.g., common salt (NaCl) can be broken into the elements sodium (Na) and chlorine (Cl). The atom of an element ― is the smallest possible particle of an element that retains that element’s properties; and ― has a nucleus, with protons and neutrons inside it, and electrons in orbit, there being as

many electrons in orbit about the nucleus as the number of protons inside the nucleus (i.e., atomic number = number of electrons or protons, atomic mass = number of protons and neutrons).

Nucleus

Electronprotonneutron

Mineral Characteristics Try http://geology.wr.usgs.gov/docs/parks/rxmin/mineral.html

to access the USGS site on the common rock forming minerals.

Minerals are the basic building blocks for earth materials. A mineral is a naturally occurring crystalline solid with its own characteristic chemical composition (O, Si, Al, Fe, Ca, Mg, K and Na being the commonest elements on earth, minerals are often made up of these elements). Minerals can be (a) native elements (e.g., gold, diamond) or (b), chemical compounds (e.g.,oxides, hydroxides, sulfides, sulfates halides, carbonates, phosphates and silicates).

Minerals can belong to cubic, tetragonal, hexagonal, ortho-rhombic, monoclinic or triclinic crystal systems. Physical properties of minerals include color (light or dark), habit (equant, fibrous, bladed, sheet), streak, fracture, cleavage, luster (metallic, vitre-ous etc.), hardness (i.e., on Moh’s scale), specific gravity or Density, magnetic and electrical properties, radio-activity, luminiscence etc.

Major Mineral Groups Visit “The Mineral Gallery” at http://mineral.galleries.com/

• Silicates: Quartz, Feldspars, Mica, Amphiboles, Pyroxenes, Olivine

• Carbonates: Calcite, Dolomite

to view the impressive collection of Amethyst

Galleries Inc.• Sulfates: Gypsum/Anhydrite, Barite • Sulfides: Chalcocite, Chalcopyrite, Pyrite,

Galena, Molybdenite, Sphalerite • Oxides: Magnetite, Hematite, Chromite,

Cuprite, Limonite, Goethite • Halides: Halite, Fluorite; Phosphates: Apatite • Native Elements: Gold, Silver, Copper, Platinum, Diamond,

Graphite

6

Understanding Silicate Minerals Earth's silica content is in the crust and the mantle. Silicate minerals are therefore the most abundant of the rock forming minerals. They are primarily build around the silica tetrahedron. This silica (SiO2) mostly occurs in combi-nation, not as free silica or quartz. For instance, combining iron and magnesium oxides (FeO and MgO) with an equal amount of silica (SiO2) produces the iron and magnesium silicate mineral, olivine, adding silica to which then produces pyroxenes and, subsequently, amphiboles. But the commonest rock-forming

Moh’s scale of hardness Hard-ness Mineral Hard-

ness Mineral 1 Talc 6 Feldspar 2 Gypsum 7 Quartz 3 Calcite 8 Topaz 4 Fluorite 9 Corundum 5 Apatite 10 Diamond

silicate mineral by far is the potassium aluminum silicate orthoclase, or K-feldspar, and its close cousins, the Ca- and Na-feldspars, or plagioclases.

Bowen’s Reaction Series, shown alongside, proposed by N.L. Bowen in 1917, conveniently explains the common observation that rocks rich in olivine, pyroxenes and calcium-rich plagioclases weather faster at the atmospheric P and T conditions than the rocks that form at lower pressures and temperatures. Want to practice writing an essay? Visit the URL: http://www.earthsci.gla.ac.uk/courses/l1/essay-how.htm for an example of using Bowen's Reaction Series to write an essay.

Hematite and jarosite on Mars? So what? Visit http://marsrovers.jpl.nasa.gov/home/, the home page of Mars Exploration Rover Mission to learn why.

10

Volcanism and the Extrusive Rocks

Kinds of Volcanism: Read this on-line USGS publication at http://pubs.usgs.gov/gip/volc

–

–

–

Fissure-type volcanism Spreading submarine ridges and rises (e.g., Reykjanes/ Mid-Atlantic Ridge, East Pacific Rise, hydrothermal vents) and the associated volcanic islands (e.g., Iceland). Large igneous provinces (LIPs) are voluminous emplacements of predominantly mafic extrusive and intrusive rock whose origins lie in processes other than 'normal' seafloor spreading. LIPs include continental flood basalts and associated intrusive rocks, volcanic passive margins, oceanic plateaus, submarine ridges, seamount goups, and ocean basin flood basalts. The most notable of continental flood basalts and flood basalt provinces are: (a) Columbia River Basalts; (b) the Ethiopian, Deccan and Siberian Traps; (c) Parana/Serra Geral, Karoo/Stromberg, Patagonian and Keweenawan Lavas; (d) Archean Komatites.

For information on LIPs on the Internet, try http://www.ig.utexas.edu/research/projects/lips/lips.html

or explore the VolcanoWorld at

http://volcano.und.nodak.edu/vw.htmlAlso available on-line, at http://adsbit.harvard.edu/books/bvtp/toc.html

is the treatise: Basaltic Volcanism on the Terrestrial Planets

–

–

Central-type volcanism

Convergent plate margins (e.g., Cascade Ranges and Pacific “Ring of Fire”) Intra-plate or “hot-spot” volcanism (e.g., Hawaii-Emperor Seamounts, Yellowstone-Snake River volcanics)

Visit the USGS volcanoe sites, starting with http://volcanoes.usgs.gov/ and its links

Volcanic materials/ products and rock classification

– – –

Lava: basaltic, andesitic, rhyolitic [in increasing order of silica (SiO2) content, with andesitic composition denoting crustal contamination] Other products: (a) Cinder Cones/Pyroclastics: Ash, Cinders, Blocks/Bombs, Lahars

(b) Gases and Gas Clouds: Nuees Ardentes, Toxics, Climate Change (c) Other materials: Pyroclasts, Volcanic Breccia

Classification: Composition: Felsic (Rhyolite), Intermediate (Andesite) and Basic or Mafic (Basalt)

Texture: glassy (Obsidian), vesicular (scoria, pumice), aphanitic (Andesite, Basalt, Rhyolite)

Precursors and/or predictors?

Seismicity (Harmonic Tremors?) Bulging or Uptilting? Gaseous Emanations?

7

11

Intrusive Activity and the Igneous Rocks

Igneous rocks are primary rocks in the rock cycle and form by solidifying from molten condition. There are two kinds of igneous rocks: plutonic and volcanic. Intrusive or plutonic rocks form from the slow cooling and solidification of magma. These intrusive bodies can form either near-surface (volcanic necks or plugs, dikes and sills) or be deep-seated (plutons like stocks and batholiths).

IGNEOUS ROCKS— Volcanic Rocks— Plutonic RocksCrystallize from initial hot melt (magma/lava)

SEDIMENTARY ROCKS— Clastic and Bioclastic— Chemical (Evaporates

and Precipitates)Form from the debris of earliermaterials by way of weathering, transportation and deposition

METAMORPHIC ROCKS— Foliated— NonfoliatedForm from reworking of pre-existing rocks by changedheat and pressure conditions

Primary Rocks

Secondary R

ocks

IGNEOUS ROCKS— Volcanic Rocks— Plutonic RocksCrystallize from initial hot melt (magma/lava)

SEDIMENTARY ROCKS— Clastic and Bioclastic— Chemical (Evaporates

and Precipitates)Form from the debris of earliermaterials by way of weathering, transportation and deposition

METAMORPHIC ROCKS— Foliated— NonfoliatedForm from reworking of pre-existing rocks by changedheat and pressure conditions

Primary Rocks

Secondary R

ocks

Intrusive rocks have phaneritic (or coarse grained) to porphyritic textures. Felsic (60-75% silica, with “free” quartz) composition dominates the intrusive

or plutonic rocks (e.g., granites and grano-diorites), compared to the mafic (with ~50% silica, no “free” quartz) basalts in the case of extrusive or volcanic rocks. Gabbro, the plutonic equivalent of basalt, is mafic while diorite, the plutonic equivalent of andesite, is of intermediate composition.

Visit the URL: http://www.dc.peachnet.edu/~pgore/geology/geo101/igneous.htm and look at the samples of different igneous rocks

Granites and granitization complete the “rock cycle” as granite batholiths, the most common plutonics, often form in the core zones of folded mountain belts through the process of dynamothermal metamorphism. Note that the primordial crust too is likely to have been granitic.

This image of a granite sample is from the USGS website on rocks and minerals at the URL:

http://geology.wr.usgs.gov/docs/parks/rxmin/rock.html#igneous

Want to take a self-test on igneous rocks and processes?

Go to the North Dakota State University’s Geoscience website at http://www.ndsu.nodak.edu/instruct/schwert/geosci/g120/igneous.htm

8

12

Weathering and Soil Weathering

Weathering implies physical disintegration and/or chemical decomposition of surface and near-surface rock material. EROSION is the physical removal of

Go to http://wwwbrr.cr.usgs.gov/projects/ SW_corrosion/GSA-poster/index.html

and read about the chemical weathering of rocks and visit the site http://wrgis.wr.usgs.gov/docs/parks/misc/gweaero.html

weathered material. TRANSPORTATION to learn of the difference between weathering and erosion is the moving of eroded material by wind, streams, waves, glaciers etc.

MECHANICAL WEATHERING (i.e., physical disintegration) • results from cosmic radiation, tides, frost action, abrasion and/or pressure release, and • causes jointing (block, sheet, exfoliation, columnar etc.)

CHEMICAL WEATHERING (i.e., chemical decomposition) • results from the chemical action of water solvents and • causes chemical and mineralogical changes, e.g., iron/aluminum oxides, caverns, stalag-

mites and stalactites, clay minerals etc.

Silica (or the mineral quartz) is the most resistant of all minerals to weathering and therefore forms the beach sands. To understand why, we need to turn to Bowen’s Reaction Series that was discussed earlier, in the context of silicate minerals. As shown here, olivine, pyroxenes and calcium-rich plagioclases weather faster at the atmospheric P and T conditions than the rocks that form at lower pressures and temperatures because minerals are most stable at the P and T conditions under which they form.

Soil

Soil is the weathered, unconsolidated, top part of rock, often rich in organic matter and therefore suitable for plant growth (lunar soil is called regolith).

Soil forms through loosening of particles, leaching by downward percolating water, and accumu-ation of clay minerals, iron oxides, calcite at the bottom of the weathered zone, while the top of bedrock defines the depth to which weathering has progressed.

Soil can be pedalfer, pedocal, lateritic, and/or bauxitic,

depending on temperature and humidity; or

LoamLoam

SiltSand

ClayPedo-

calPedal-

fer

Laterite/Bauxite

Go to http://www.essc.psu.edu/soil_info/soil_land/us_soil_surveys

and browse an interactive map of U.S. soil surveys

Dry

Hum

id

Warm

Cold

arnacious (sandy), argillaceous (clayey) and/or calcarious (loam), depending on the mineral and/or composition.

9

13

Mass Movements and Mass Wasting

Mass movements are the gravity driven down-slope movements of earth mate-rials, in bulk or “en masse”, that result from slope instability.

horizontal

Verticalgravitational pulltowards earth’s center

Component of gravitational

force parallel to hill-slope

– – – – – –

The instability of a slope resGeology (i.e., the rock types aGeometry Fluids: (a) precipitation, (b) groundwater and its withdrVegetation Earthquakes, volcanism Construction/human activitiesseptic tanks, road-cuttings, reirrigation facilities etc.

main fomas

–

–

(a) (b)

Consequences of mass movements:

Stabilizing a slope A common practice, if structuravalanche zone is narrow, is tIf a slope is too steep to be stthe slide potential:

Reducing the slope angle Placing additional support material at the foot of the slope to prevent a slide or flow at the base of the slope

Of these, “modifying” the slope gesuccessful, and therefore most co

Read this USGS online report on real-time monitoring of active landslides at the URL: http://vulcan.wr.usgs.gov/Projects/CalifLandslide/Publications/ ReidLaHusen/report_inlined.html

Gravity is therce that drives s movements.

– – – –

ults from Types of mass movements: nd structures)

awal

Creeps Rockfalls Slumps and landslides Flows and avalanches

, e.g., homes, servoirs and

This geological section of the 1925 Gros Ventre, Wyoming, land-slide shows the contributions of water saturated sandstone layer and the underlying sloping clay beds

CREEPEARTHFLOW

AVALANCHE

MUDFLOW

SLUMP

SLIDE

ROCKFALLSUBSIDENCE

Extremelyslow

Extremelyrapid

Dry

Saturated

CREEPEARTHFLOW

AVALANCHE

MUDFLOW

SLUMP

SLIDE

ROCKFALLSUBSIDENCE

Extremelyslow

Extremelyrapid

Dry

Saturated

(c)

(d)

(e)

– Fatalities, damage and destruction – Disrupted communications – Floods, unplanned and unstable dams and reservoirs, and

related disasters

es to be protected are few or small and/or the landslide/ o bridge the structure that the slides flow over. able under the load it carries then following measures can reduce

Reducing the load (weight, shearing stress) on the slope by removing some of the rock, soil or artificial structures high on the slope Constructing retention structures (retaining walls, ground covers), vegetation Fluid removal by improving drainage

ometry and load and “dewatering” have proven to be the most mmonly used, strategies.

10

14

Sediments and Sedimentary Rocks

– – –

– – –

A sediment is a collection of loosened particles of solid rock originating from

weathering and erosion of preexisting rocks chemical precipitation organic secretion or organic debris

SEDIMENTARY ROCKS form from consolidation, compaction and lithification/ diagenesis of the sediments. This involves

weathering and erosion transportation and deposition lithification and diagenesis

PETROLOGY OFSEDIMENTARY ROCKS

ROBERT L. FOLK

Hemphill Publishing CompanyAustin, Texas 78703

Click at the URL below or go to http://www.lib.utexas.edu/Libs/GEO

/FolkReady/TitlePage.html to read this online book on this

subject

Other resources on the world wide web:

This USGS site has images and movies of cross-bedding and bedform features in sedimentary rocks: http://walrus.wr.usgs.gov/seds

This University of Oregon site, http://darkwing.uoregon.edu/~dogsci/dorsey/SedResources.

htmlhas a comprehensive list of web resources on Sedimentary Geology.

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–

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CLASSIFICATION OF SEDIMENTARY ROCKS CLASTIC SEDIMENTARY ROCKS lithify from the sediments, e.g., conglomerates and breccia, sandstones, shales ORGANIC, BIOGENOUS or BIOCLASTIC SEDIMENTARY ROCKS consolidate from the organic remains, e.g., coal, limestones (such as oolites, coralline limestones), chert etc. CHEMICAL or HYDROGENOUS SEDIMENTARY ROCKS either a. precipitate from solution (e.g., carbonates like limestones and dolomites) or b. form as evaporates (e.g., gypsum, rock salt).

The common sedimentary structures include bedding, cross-bedding, ripple marks, folds, faults and unconformities.

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15

Metamorphism and the Metamorphic Rocks

Metamorphism is the solid-state physicochemical (i.e., the textural and/or mineralogical) alteration of preexisting rock by changes in the pressure and/or temperature conditions.

– – –

These factors affect metamorphism:parent rock’s mineral composition; the temperature changes that affect mineral stability; pressure that may be (a) confining or static pressure which squeezes grains together; so reducing the porosity and producing a denser

This USGS website on North Cascades Geology http://wrgis.wr.usgs.gov/docs/parks/noca/nocageol2c.html

has an interesting presentation on metamorphic rocks

or visit the following University of British Columbia website

http://www.science.ubc.ca/~geol202/meta/metamorphic.html to learn about the metamorphic rocks and processes.

and finer grained rock, or (b) directed (or dynamic) pressure which aligns platy minerals and produces shearing and foliation; and

–

often water vapor, and sometimes CO2, aid mobility and the reconfiguration of ions.

The classification of metamorphic rocks – FOLIATED rocks are

named texturally as (a) slaty, (b) phyllitic,

(c) schistose and (d) gneissic

–

(a)

(b)

NONFOLIATED rocks are named on the basis of composition.

Types and facies of metamorphism

quartzite and marble have coarse interlocking grains of quartz and marble, respectively; hornfels are fine-grained with (i) micaceous minerals if they are derived from shales, (ii) mafic and plagioclase minerals when they are derived from basalts, and (iii) metaconglomerates

– – – – –

Contact or thermal metamorphism Regional or dynamothermal metamorphism Metasomatism (involves extraneous chemical changes) Hydrothermal alterations/vein mineralization Metamorphic facies is the grade concept of metamorphism that includes the effects of pressure and temperature, using indicator mineral assemblages, to infer the P/T conditions.

Read more about this concept at:http://duke.usask.ca/~reeves/prog/geoe118/geoe118.029.html

Granitization (follows migmatization) as the ultimate stage of metamorphism and completes the rock cycle.

Learn about the granites from Rob’s Granite page at

http://uts.cc.utexas.edu/~rmr/definition.html

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16

Streams and Landscapes –

–

–

Running water is

the run-off of excess precipitation from land to the oceans that completes the hydrological cycle; the most important geologic agent for (a) erosion, transportation and deposition of sediments, and (b) landscape development.

Typically, 15-20% of rainfall in the hydrologic cycle becomes surface runoff, usually through streams, but also as sheet wash under favorable conditions (e.g., in the deserts). Stream, a gravity driven channel flow,

removes water from a drainage basin (internal or external) separated from other basins by the divides;

The hydrologic Cycle

Evaporation= 15 x 109

milliongallons

Land

World Ocean = 362 x1012 million gallons

Evaporation= 85 x 109

milliongallons Precipitation

= 75 x 109

million gallons

Precipitation = 25 x 109

million gallons

Run-off= 1010

milliongallons

Following USGS sites offer excellent introduction to and information on surface water resources:

http://ga.water.usgs.gov/edu/http://water.usgs.gov/data.html

– –

is typically antecedent in Southern California; and can have dendritic, radial, trellis etc. drainage patterns that reflect rock type and structure.

The longitudinal profile of a stream reflects its gradient: It is steep at headwaters (juvenile phase) with V-shaped valley, gentler when it enters the plains (adult phase) where it meanders in a broad valley with a flood plain, and nearly flat towards its mouth (mature phase) where a delta forms.

Stream erosion, transportation and deposition are controlled by (a) velocity (governed by channel shape and roughness, volume of water) and (b) discharge (= volume per unit time = flow velocity × area of channel’s cross-section) Specifically, (a) erosion involves hydraulic action, solution and abrasion; (b) transportation occurs through bed load/saltation (sand and gravel), suspension (silt and clay) and solution; while (c) deposition occurs with drop in velocity (e.g., formation of flood plains, channel-fills and levees, meander loops and placer beaches, deltas and alluvial fans ⎯ sediment supply, waves and shoreline currents control the shape of a delta).

– – –

–

Regional erosion by streams is controlled by climate (angular landforms in dry climates and rounded landforms in wet climates), rock type (slope angle decreases with the overburden grain size) and structure (folded and faulted rocks depart from the staircase character of horizontal beds).

Landscapes reflect either a reduction of slope angles from erosion approaching base level or parallel retreat of slopes across a region.

Stream terraces reflect either regional uplift which lowers the base level and promotes down-cutting or change from dry to wet climate (which increases a stream’s erosional capacity).

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17

http://www.ndsu.nodak.edu/instruct/sainieid/group/100-year.htm

Flood Frequency Analysis and Determination of 100-year and 500-year Floods Bernhardt Saini-Eidukat, Department of Geosciences, North Dakota State University Leopold (1994)1 describes a flood frequency curve (see below) as the relation of the size distribution of flood occurrences at a given location on a river to the frequency of these occurrences. To determine the size of a flood occurrence, either the highest annual discharge can be tabulated to form an annual flood series, or all discharge levels above an established limit can be tabulated without regard to annual occurrence. In either case, the data series represents only a sample of the discharge events at the given location, and the observed size distribution may not represent the largest or smallest peak discharge events possible. For this example, let's use the annual flood series method. To estimate probability that any discharge will be equaled or exceeded in any given year, the peak discharges are ranked from m = 1 (largest), m = 2 (second largest) and so on to m=n, where n is the number of years in the data record. For each data point, a Recurrence Interval (RI) is calculated using the Weibull equation RI = (n+1)/m which is the average time interval between the occurrence of two discharge events of a given or greater size (Lundgren, 1986, p. 240)2. The RI is the reciprocal of the probability of an occurrence. As an example, in the flood record of the Red River of the North at Fargo, North Dakota, the 11th highest discharge was 11,200 cubic feet per second on April 3, 1994 during the 112 year record (1882 - 1994) in the National Water Data Storage and Retrieval System (WATSTORE) database for North Dakota. The Recurrence Interval of this discharge level is 113/11 or about 10 years, and the probability of a flood discharge of this size occurring in any one year is 1/10, or about ten percent. The 100-year flood level is that gage height that corresponds to the discharge at RI = 100, which has a probability of being met or exceeded of 1%. Similarly, the 500-year flood level is that gage height corres-ponding to the discharge extrapolated at RI = 500, which has a probability of being met or exceeded of 0.2 %. To determine the flood plain that will be inundated by a 100- or a 500-year flood, compare the topography of the area adjacent to the river to the predicted gage height.

Gage Discharge Gage DischargeHt (ft.) (CFS) Ht (ft.) (CFS)

14 263 29 1080015 899 30 1190016 1850 31 1320017 2730 32 1470018 3460 33 1650019 4060 34 1830020 4640 35 2050021 5220 36 2290022 5780 37 2540023 6340 38 2810024 6950 39 3100025 7590 40 3400026 8260 41 3710027 9060 42 4050028 9900 43 44000

How do you translate from discharge to gage height, or vice versa? The USGS has tables of discharge vs. gage height for each gaging station. For example, if you scroll to near the bottom of the gage for Fargo, you'll see a table that shows discharge vs.gage height. Shown alongside is a part of that table.

1 Leopold, Luna B., 1994, A View of the River:

Cambridge, Massachusetts, Harvard University Press, 298 p.

2 Lundgren, L., 1986, Environmental Geology: Prentice-Hall, Upper Saddle River, New Jersey, 576 p.

Underground Water

– –

–

Groundwater accounts for ~15% of the precipitation; is our largest source of freshwater (35-100 times the surface water supply); and fills pore space, cracks and crevices in rocks beneath the ground surface. The quantity of groundwater that the hydrological cycle contains remains open to speculation and uncertainties,however (see Table). Porosity and permeability reflect the ability of a subsurface horizon to hold

OceansPore water in the

sedimentsIce-caps, glaciers

Rivers, lakesAtmospheric

moisture

Total hydrosphere

Total mass(trillion tons)

1,370,000

330,00020,000

300

13

1,720,313

Share of thehydrosphere

80%

18.8%1.2%0.02%

0.0008%

100%

Considering all sediments*

Total mass(trillion tons)

1,370,000

7,00020,000

300

13

1,397,313

Share of thehydrosphere

97%

0.5%1.4%

0.02%

0.0009%

100%

Conventional estimates

*Karl K. Turekian: GLOBAL ENVIRONMENTAL CHANGE (Prentice Hall, 1996) and move groundwater. Downward percolation of ground water continues until porosity ends. Filling saturates porosity in a saturated zone, the top of which in an unconfined aquifer is the water table. Unsaturated zone above the water table is the zone of aeration. Lenses of impermeable rock may produce local water tables above the main water table.

–

Groundwater flow follows Darcy’s Law: velocity = permeability × hydraulic gradient

Aquifers carry groundwater, may be confined, in layered formations when a porous and permeable horizon is sandwiched between two impermeable layers or aquicludes: in this case we have (a) potentiometric surface, and (b) artesian springs; or

– unconfined (i.e., the bottom part of the weathered zone, immediately above the bedrock), in which case we have the water table and wells must be drilled into the saturated zone in order to tap water.

Groundwater interacts with surface water in gaining and losing streams.

Go to http://water.wr.usgs.gov/gwatlas/index.htmlto browse the groundwater atlas of US

Polluted groundwater is a serious problem: Human activity produces potential pollution from pesticides, herbicides, fertilizers, heavy metals and toxic compounds, bacteria, viruses and parasites from animal, plant and human waste, acid mine drainage, low and high level radioactive waste, and oil seepage. Other problems include groundwater withdrawal and calcitization, saltwater intrusion, and subsidence through compaction. Caves, sinkholes and karst topography result from the solutional effects of groundwater. Groundwater may also form petrified wood, concretions, geodes, cement sedimentary rocks, and develop alkaline soils. Hot springs and geysers, with their associated deposits of sinter (silica) and travertine (calcite), reflect the rise of hot groundwater and can be tapped as geothermal energy.

Deserts and Wind ActionDeserts

are “arid” or dry regions (i.e., regions that receive <25 cm (or <10 inches) of annual precipitation and

c monly occur at om– – – – –

about 30° N and S latitudes and the poles, i.e., where air pressure is usually high the rain shadows of mountains, continental interiors, the proximity to cold ocean currents, and/or high altitude Visit http://pubs.usgs.gov/gip/deserts/contents/

to read this USGS online publication on deserts.

source: http://pubs.usgs.gov/gip/deserts/what/world.html

Desert landforms

Of these, atmosphere plays the most important role. Deserts worldwide are found at ~30° N and S latitudes, to-wards the western margins of land, and at the South Pole. Note that ~30° N and S are also the latitudes at which sea surface waters are particularly salty, because evaporation exceeds precipitation. Air pressure is high at these latitudes. A separate handout is being provided on atmospheric circulation and weather in the attached handout. The model shown below is from the URL: http://pubs.usgs.gov/gip/deserts/atmosphere/

– –

–

Dunes typically characterize the deserts and form under winds that blow from one direction. Crescentic or crescent-shaped mounds that are generally wider than long, with slipface on the concave side, are the most common dune form on Earth and on Mars. The other types of dunes are linear, star, dome, and parabolic.

Desert streams tend to be – –

intermittent rather than perennial, and characterized by (a) internal drainage (e.g., Colorado, Niger, Amu and Syr darya); and (b) flash flooding. Sahara once received almost 18 inches of rain in a 3-hour period, for instance.

Desert of Southwestern U.S. – –

reflect partly the latitude effect and partly the rain-shadow effect; and are characterized by flat lying sediments in Colorado plateau and (b) block faults in the Basin and Range province.

Wind action

Visit the above USGS site at http://terraweb.wr.usgs.gov/TRS/projects/eolian/eolianmp.html

for information on aeolian mapping and related issues or go to http://www.desertusa.com/ to browse multimedia desert

life related articles in the online magazine “desertUSA”

– – –

also creates the erosion, transportation and deposition of sediments (aeolian sediments), depending on wind speed (and air temperature), topography and geology; typically produces LOESS deposits (e.g., the U.S. Midwest and China) and sand dunes; and combines with Southern California Sun to produce the Los Angeles SMOG through thermal inversion.

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18

Atmospheric Circulation and Weather Ocean-atmosphere interactions (a) moderate surface temperatures, (b) shape the earth’s overall weather and climate, and

(c) create ocean waves and currents. Atmosphere is the solid earth’s ~110 km thick gaseous envelope; weather

is the atmosphere’s state at a given point in time and space; and climate is the weather’s yearly averaged seasonal composite.

In the near-surface region that we are interested in, i.e., the troposphere (it extends to 10-15 km above earth’s surface and carries ~90% of the atmospheric mass), average temperatures decrease as we go up.

The atmosphere — is uniquely rich in N2 (78%) and O2 (21%) - Moon and Mars lack an

atmosphere, atmosphere of Venus is CO2-rich (~96%), while Jupiter and Saturn have H and He dominated atmospheres;

— evolved in three phases: (1) H, He rich early phase of ~4.5 Ga ago, (2) CO2, N2 and H2O rich middle phase of ~3.7 Ga ago and (3) N2 and O2 rich present phase since ~1.25 Ga ago.

Where did Earth’s CO2 go?

― Atmosphere has ~0.03% CO2, Seawater ~60 times as much. ― Carbonates (e.g., limestones) precipitate in the ocean bottom. Indeed, most of this C is

now locked up in limestones and marble. Oceans have thus depleted the earth’s atmosphere of its CO2 content.

Three forces mainly drive atmospheric circulation: (a) differential solar heating of earth’s surface, (b) gravity, i.e., equatorial bulge versus polar flattening, and (c) rotation.

As solar heating of the earth’s surface varies with latitude, — earth’s elliptical orbit and 23½° tilt of spin axis create seasons; and ― evaporation dominates radiation in the tropics while water freezes at the polar latitudes to create icecaps.

Moisture–laden warm air that rises at the equator cools down and must sink but (a) travels polewards as gravity at the poles exceeds that at equator and (b) begins equatorward return as cold surface air after sinking at the pole, so creating a convective cell.

Being basically unstable, this single cell breaks down into three, at 30° and 60° (N and S) latitudes. This creates (a) high pressure zones of sinking air masses at the 30° N and S latitudes and poles (these latitudes thus have deserts on land and high surface water salinity in the oceans), and (b) low pressure zones of rising air masses at the 60° N and S latitudes and equator (these latitudes thus have rain forests on land and low surface water salinity in the oceans).

The Coriolis deflection of these convection cells in the direction of Earth’s spin now creates: ― westward surface winds (“trade winds”) at 0°-30°N and 0°-30°S, ― eastward surface winds (“prevailing westerlies”) at 30°-60°N & S, and ― westward surface winds (“polar easterlies”) at 60°-90°N and S.

Equatorial surface air thus flows against earth’s spin direction. Warm surface waters thus stack up on the western margins of tropical/semi-tropical oceans, with the following results: ― Warm surface waters stack up on the western margins of

tropical/semitropical oceans. This (a) deepens the thermocline on the western coasts, so producing generally humid climatic conditions on one hand and poor fishing conditions on the other; and (b) creates breeding grounds for tropical storms/cyclones on these western margins.

― Upwelling of cold deep waters on the opposite eastern coasts produces arid climates on one hand but excellent fishing on the other.

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19

Global warming will make Europe cold and dry, abruptly,

according to the National Research Council*.

Why this opposite effect? To understand this, we need to look at

the distribution of water on Earth, and water’s latent heat, to see how global warming is likely to affect the northern and southern hemispheres differently, andthe ocean currents that keep Europe unusually warm for its location.

* SCIENCE & POLICY IMPLICATIONS OF ABRUPT CLIMATE CHANGE: National Research Council (National Academy Press, Washington DC: April 2002)

Europe currently has an unusually warmer and wetter climate for its high-latitude location.

according to the National Research Council*.

Why this opposite effect? To understand this, we need to look at

the distribution of water on Earth, and water’s latent heat, to see how global warming is likely to affect the northern and southern hemispheres differently, andthe ocean currents that keep Europe unusually warm for its location.

* SCIENCE & POLICY IMPLICATIONS OF ABRUPT CLIMATE CHANGE: National Research National Academy Press, Washington DC: April 2002)Council (

Europe currently has an unusually warmer and wetter climate for its high-latitude location.

water’s latent heat of fusion is 80 cal/gm, and its latent heatevaporation is 585 cal/gm, i.e., the heat needed to evaporategram is water is enough to melt 7 times as much ice.

Therefore, global warming should affect the NorthernSouthern hemispheres in significantly different ways

N. Hemisphere587.6 billion Km3

2.8 billion Km3

S. Hemisphere782.4 billion Km3

30.1 billion Km3

OceansIcecaps,

Sea-ice & glaciers 1 Km3 = 262.4 billion gallons

Northern hemisphe60.7% sea and 39.3land, while the Souhemisphere is 80.9%and 19.1% land; anice accounts for a smproportion of waterNorthern hemisphe(0.47%) than in theSouthern hemisphe(3.7%).

Earth has a hemi-spherically asymmdistribution of landwater.

water’s latent heat of fusion is 80 cal/gm, and its latent heatevaporation is 585 cal/gm, i.e., the heat needed to evaporategram is water is enough to melt 7 times as much ice.

Therefore, global warming should affect the NorthernSouthern hemispheres in significantly different ways

N. Hemisphere587.6 billion Km3

2.8 billion Km3

S. Hemisphere782.4 billion Km3

30.1 billion Km3

OceansIcecaps,

Sea-ice & glaciers 1 Km3 = 262.4 billion gallons

N. Hemisphere587.6 billion Km3

2.8 billion Km3

S. Hemisphere782.4 billion Km3

30.1 billion Km3

OceansIcecaps,

Sea-ice & glaciers 1 Km3 = 262.4 billion gallons

Northern hemisphe60.7% sea and 39.3land, while the Souhemisphere is 80.9%and 19.1% land; anice accounts for a smproportion of waterNorthern hemisphe(0.47%) than in theSouthern hemisphe(3.7%).

Earth has a hemi-spherically asymmdistribution of landwater.

The 20th century Data reflect this, with

correlated rises, since 1900, of 0.6ºC in mean global temperatures and ~10 cm in the mean sea level worldwide; andincreased precipitation at higher latitudes, in the Northern hemisphere, and relative aridity at the lower latitudes, compared togreater precipitation throughout the Southern hemisphere, but for ~20ºS.

correlated rises, since 1900, of 0.6ºC in mean global temperatures and ~10 cm in the mean sea level worldwide; andincreased precipitation at higher latitudes, in the Northern hemisphere, and relative aridity at the lower latitudes, compared togreater precipitation throughout the Southern hemisphere, but for ~20ºS.

Oceans modulate the climate, irrespective of whether global warming is anthopogenic or not.

Oceans modulate the climate, irrespective of whether global warming is anthopogenic or not.

a

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1880 1900 1920 1940 1960 1980 2000

0

8

-8

Mean Sea level relative

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ean

glob

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tem

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s re

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Sources: (a) For temperature data: http://www.giss.nasa.gov/data/update/gistemp/graphs(b) For sea level data: T.P. Barnett, in CLIMATE CHANGE (IPCC Working Group Report: Cambridge University Press, 1990)

a

-0.6

-0.4

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Mean Sea level relative

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Sources: (a) For temperature data: http://www.giss.nasa.gov/data/update/gistemp/graphs(b) For sea level data: T.P. Barnett, in CLIMATE CHANGE (IPCC Working Group Report: Cambridge University Press, 1990)

Land as the % of Earth’s surfacearea per 1º

latitude band

40oS

0o

40oN

0

- 10% 10%0%Precipitation Change (1900-94)

10.5

Recomputed from the data in Thomas Karl, Neville Nicholls & Jonathan Gregory: The Coming Climate, Scientific American, May 1997

Land as the % of Earth’s surfacearea per 1º

latitude band

40oS

0o

40oN

0

- 10% 10%0%Precipitation Change (1900-94)

10.5

Recomputed from the data in Thomas Karl, Neville Nicholls & Jonathan Gregory: The Coming Climate, Scientific American, May 1997

A recent analysis of Earth’s heat balance* goes a step furthequantitatively demonstrating that, during the latter half of t20th century, changes in the ocean heat content have dominthe changes in Earth’s heatbalance.Much of this heat appears tohave gone particularly into thewarming of Atlantic waters.

* S. Levitus, J.I. Antonov, J. Wang, T.L. Delworth, K.W. Dixon & A.J. Broccoli: Anthropogenic warming of Earth’s climatic system. Science, 292: 267-270 (2001).

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A recent analysis of Earth’s heat balance* goes a step furthequantitatively demonstrating that, during the latter half of t20th century, changes in the ocean heat content have dominthe changes in Earth’s heatbalance.Much of this heat appears tohave gone particularly into thewarming of Atlantic waters.

* S. Levitus, J.I. Antonov, J. Wang, T.L. Delworth, K.W. Dixon & A.J. Broccoli: Anthropogenic warming of Earth’s climatic system. Science, 292: 267-270 (2001).

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http://www.nodc.noaa.gov/OC5/WOA98F/woaf_c

Two kinds of currents transfer this heat across the oceans:

The resulting change is likely to be abrupt*,

the oceans: wind-driven surface currents like the Gulf Stream that carry warm tropical waters to the higher latitudes, andthe Global Conveyor Belt1 of thermohaline cir-culation that mixes all the surface and deep waters and is particularly sensitive to changes in the hydrological cycle2.

1 W.S. Broecker: “The great ocean conveyor”, Oceanography, 4: 79-89 (1991) and “Chaotic Climate”, Scientific American, Nov 1995.

2 S. Rahmstorf: Bifurcation of the Atlantic thermohaline circulation in response to changes in the hydrological cycle. Nature, 378: 145-149 (1995).

the oceans: wind-driven surface currents like the Gulf Stream that carry warm tropical waters to the higher latitudes, andthe Global Conveyor Belt1 of thermohaline cir-culation that mixes all the surface and deep waters and is particularly sensitive to changes in the hydrological cycle2.

1 W.S. Broecker: “The great ocean conveyor”, Oceanography, 4: 79-89 (1991) and “Chaotic Climate”, Scientific American, Nov 1995.

2 S. Rahmstorf: Bifurcation of the Atlantic thermohaline circulation in response to changes in the hydrological cycle. Nature, 378: 145-149 (1995).

g g y p ,based on the evidence from Greenland and Antarctic ice cothe warming that began in the Younger Dryas started withpresent Conveyor Belt and was aaccomplished rapidly; whichraises the alarming possibility that Europe may suddenly revert to its Mini Ice Age (c. 1300-1900) in a matter of decades.

Data Sources: Alley et al., Nature, 362: 527-52Grootes et al., Nature, 336: 552Blunier et al., Nature, 394: 739-

* P.U. Clark, N.G. Pisias, T.F. StockeWeaver: The role of the thermohalilation in abrupt climate change. Na863-869 (2002).

Temperature change expected by 2,050 AD should the present warming trend continueSource: http://www.giss.nasa.gov/data/update/gistemp

g g y p ,based on the evidence from Greenland and Antarctic ice cothe warming that began in the Younger Dryas started withpresent Conveyor Belt and was aaccomplished rapidly; whichraises the alarming possibility that Europe may suddenly revert to its Mini Ice Age (c. 1300-1900) in a matter of decades.

Data Sources: Alley et al., Nature, 362: 527-52Grootes et al., Nature, 336: 552Blunier et al., Nature, 394: 739-

* P.U. Clark, N.G. Pisias, T.F. StockeWeaver: The role of the thermohalilation in abrupt climate change. Na863-869 (2002).

Temperature change expected by 2,050 AD should the present warming trend continueSource: http://www.giss.nasa.gov/data/update/gistemp

Temperature change expected by 2,050 AD should the present warming trend continueSource: http://www.giss.nasa.gov/data/update/gistemp

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thern sea

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in the re

re

etric and

r, by heated

d/search.html

r, by heated

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res, that the

9 (1993); -554 (1993); 743 (1998).

Younger Dryas

r & A.J. ne circu-ture, 415:

res, that the

9 (1993); -554 (1993); 743 (1998).

Younger Dryas

Younger Dryas

r & A.J. ne circu-ture, 415:

Glaciers and Glaciation

–

Glaciers and polar ice caps are the frozen masses of water that carry ~2% of the hydrospheric water supply.

Glacial flow is sluggish (1 mm-15 m/day)

Snow Line, the elevation above which water is always frozen, varies with

(a) altitude, (b) latitude and (c) season.

Types of glaciation:

continental glaciation (>50,000 km2 in area) and ice sheets account for ~95% of all glacial ice (e.g., Antarctica ≈ 85% and

This site http://www.glaciers.net/ is a good place to visit for professionals, students, and hobbyists interested in glacial processes and landforms.

Greenland ≈ 10%); –

–

– –

ice caps (<50,000 km2 extent), e.g., the Tundras; Alpine or valley glaciers (seen in the mountain valleys); and piedmonts or the glacial lakes.

Glacial budget: net gain of snow occurs in the zone of

Browse the satellite image atlas of world’s glaciers at USGS site http://pubs.usgs.gov/factsheet/fs133-99//

Another excellent resource for glaciologists is the USGS Open-File Report 98-31 on long-term monitoring of glaciers in North America and

Northwestern Europe that can be web-accessed at http://chht-ntsrv.er.usgs.gov/Glacier_wkshp/toc.htm

accumulation, where addition exceeds loss, whereas –

– – –

net loss of snow characterizes the zone of ablation.

This book “Looking South: The Australian

Antarctic Program

Glacial erosion: produces rock flour, varves, striations; carves “U-shaped” valleys and fjords; and forms (a) lateral, (b) medial and (c) end (i.e.,

into the 21st Century” is now available as Adobe

Acrobat PDF files at the site http://www.antdiv.gov.au/s/f.plx?/resources/looksth/index

.html

terminal and recessional) moraines and (d) drumlins.

Questions about the past ice ages (Milankovitch cycle*) and climate changes (also continental drift) arouse geological and paleoenvironmental interest. As for the first of these, the recurrent Ice Ages and Inter-glacial warm periods observed in the earth’s most recent past 2 Ma history, were ascribed by Milankovitch to the 21000, 41000 and 100000 year variations in earth’s

Visit the NOAA (National Oceanic and Atmospheric

Administration) Paleoclimatology

program at http://www.ngdc.noaa.gov/paleo/paleo.html

orbital relationships and wobble. As for the latter, recall that Alfred Wegener’s reconstruction of Pangea, an assembly of all the landmasses, at the South Pole was made to explain the observed 250 Ma glaciation in such presently far flung landmasses as South America, Africa, India, Australia and Antarctica.

*Read about the “Milankovitch Cycles in Paleoclimate” at http://deschutes.gso.uri.edu/~rutherfo/milankovitch.html

Learn the geological history of Glacier National Park at http://www.nps.gov/glac/

2

20

Waves, Beaches and the Coast Waves are – single or complex sinusoidals, that can be

either capillary or gravity, of which – –

gravity waves can be wind-driven, tidal or tsunamis. As (a) gravity waves are faster the longer they are and (b) a basin must be at least twice as deep as the length of the wave, the wind generated ocean waves break as they approach the shore, at the

Following are some of the USGS sites of interest here: http://walrus.wr.usgs.gov/hazards/

erosion.html http://www.nap.edu/books/030906

5844/html/ http://marine.usgs.gov/

surf zone. This creates longshore current and littoral drift.

Tides – –

have diurnal, semidiurnal and mixed cycles, are stronger (spring tides) during the full and new moon when the luni-solar gravitational pulls add up, and

Try http://co-ops.nos.noaa.gov/about2.html for information on water levels, tides and currents

– weaker (neap tides) during the first and third quarter of moon when the two (i.e., lunar and solar) gravitational pulls are mutually perpendicular.

Tsunamis are –

–

seawaves generated by ocean-bottom seismicity (e.g., earthquakes, volcanism and/or landslides); and common on the Pacific shores because of the tectonic nature of this ocean’s boundaries.

Browse the site of Netherlands Coastal Zone Management Center at

http://www.minvenw.nl/projects/netcoast/coast/coast.htm

Beaches: –

–

–

Beach slope determines the way the waves break (spilling versus plunging and/or surging breakers). Berm is located above the level of highest wave activity, beach-face (or backshore) is above water all the time, and marine (or tidal) terrace (i.e., foreshore) is exposed during the low tides. Sand stays on the beach because it is

This NOAA (National Oceanic and Atmospheric Administration) site provides links to extensive data and

sites on waves and tides: http://www.pmel.noaa.gov/bering/pages/env_wave.html

For information on tsunamis, try this NASA site: http://observe.ivv.nasa.gov/nasa/exhibits/tsunami/tsu

n_bay.html

continually recycled between the shore and the surf zone. – In temperate zones, longshore bar grows at the cost of the berm in the

winter, when wave activity is strong, while berm grows at the cost of the longshore bar during summer, when wave activity is weak.

Coasts can be

3

– –

active (i.e., tectonic) versus passive. depositional (e.g., deltas) or erosional (e.g., fjords).

Human interference causes coastal erosion, e.g., groins produce beach-growth upstream of longshore current, shifting erosion downstream, while breakwater wall has beach-growth behind it and intensifies coastal erosion on its flanks.

Issues to ponder about

– – –

Global warming and the coastal habitat, agriculture, climate etc. Coastal construction (sea walls) and marine erosion Marine pollution and waste disposal

21

Geologic Resources ― (a) Minerals

– –

–

The geological or extractive earth resources are essentially nonrenewable and can be broadly grouped as

mineral (metallic and nonmetallic) and energy (fossil fuels, nuclear) resources.

Kinds of mineral resources: Metallic minerals: These include ferrous metals (ores of iron,

Earth resourcesRenewable• Direct (solar)• Other (wind, tides, groundwater, oceans)

PotentiallyRenewableFresh air, water, soil

Nonrenewable• Fossil fuels (coal, oil, natural gas)• Radioactive minerals• Metallic, nonmetallic and industrial minerals

manganese, chromite, nickel, cobalt etc.), non-ferrous metals or polymetallic deposits (ores of copper, lead, zinc, tin, tungsten etc.) and precious metals ⎯ their suitability for mining is defined by their concentration factor (this value is 60 ppm for copper, 2 ppm for tin, 4 ppb for gold etc., i.e., the more scarce the resource is the smaller its concentra-

Visit the USGS mineral resources website http://minerals.usgs.gov/

tion need to be for its cost-effective extraction). – Nonmetallic and industrial minerals:

These include such gemstones as diamond, ruby, sapphire, amethyst etc. and industrial minerals and materials like barite, gypsum, halite etc.

Concentration Factor Concentration of the metal in the ore depositConcentration of that metal in average crust=

– Occurrence of mineral resources:

Deposits in igneous and metamorphic rocks: Metallic deposits like those of chromium, platinum and iron often occur in crystal setting within cooling magma. Polymetallic deposits of copper, lead, zinc, gold, silver, nickel, cobalt, tin, tungsten, molybdenum, mercury and iron occur as hydrothermal deposits (contact metamor-phism, hydrothermal veins, disseminated deposits and hot-spring deposits). Pegmatites often carry lithium, mica, rare metals and barites. Polymetallic deposits usually occur in folded mountain belts. Notice how porphyry copper and molybdenum deposits dot the entire subduction zone from Andes to the Cascades. Almost all the U.S. reserves of gold, silver, platinum and palladium come from the western U.S., from Rockies to the Sierras and Cascades.

– Other types of ore deposits: include the chemical precipitation in layers, in the case of most of iron and manganese and some copper deposits,

placer deposits of gold, tin, platinum and titanium, and concentration by weathering and groundwater (e.g., of diamond brought to the surface from kimberlite pipes; forming of bauxite and laterite by chemical weathering), and the supergene enrichment of disseminated ores.

1900 1925 1950 20001975

200

100

Pric

e (1

977-

79 =

100

)

Long-run inflation-adjusted world prices for nonferrous metals

(aluminum, copper, tin and zinc)

1900 1925 19501900 1925 1950 20001975

200

100

Pric

e (1

977-

79 =

100

)

Long-run inflation-adjusted world prices for nonferrous metals

(aluminum, copper, tin and zinc)

Exhaustibility of mineral resources: A typical problem with mineral and similar earth resources is their exhaustibility. Since our need for these resources has only been rising, this means that their prices too should rise, particularly because, with increasing use, their supply is only likely to decline. But, as this graph shows, inflation adjusted prices of four of the most used nonferrous metals ― aluminum, copper, tin and zinc ― has mostly stayed steady about the 1978 levels.

4

22

Geologic Resources ― (b) Energy Resources

Fossil fuels: These comprise coal, oil and natural gas, all of organic origin. Of these, coal forms from plant

remains (ancient rain forests ⇒ peats and bogs ⇒ lignite ⇒ coal) and occurs in sedimentary layers. Oil and natural gas, on the otherhand, form from decomposition of shallow marine microorganisms and are found in suitable ‘traps’ (structural and stratigraphic). The rising demand for the fossil fuels (they accounted for 85% of world’s 2000 energy use) means that the supplies of these ex-

For energy resources, a starting point would be US Department of

Energy site http://www.osti.gov/

haustble resources should drop and their prices should rise. That

Oil (43%)

Natural Gas (21%)

Coal (21%)

Nuclear (9%)

Renewa-bles (6%)

Oil (43%)

Natural Gas (28%)

Coal (18%)

Nuclear (7%)

Renewa-bles (4%)

2000 2020

Source: www.eia.doe.gov

Oil (43%)

Natural Gas (21%)

Coal (21%)

Nuclear (9%)

Renewa-bles (6%)

Oil (43%)

Natural Gas (21%)

Coal (21%)

Nuclear (9%)

Renewa-bles (6%)

Oil (43%)

Natural Gas (28%)

Coal (18%)

Nuclear (7%)

Renewa-bles (4%)

Oil (43%)

Natural Gas (28%)

Coal (18%)

Nuclear (7%)

Renewa-bles (4%)

2000 2020

Source: www.eia.doe.gov

$10

$20

$30

$40

$50

1970 1980 1990 2000

2.0%

2.5%

3.0%

3.5%

4.0%

Fraction of Proved R

eserves Used (per year)R

eal P

rice

of C

rude

Oil

(per

bar

rel)

xxx

x

x

xxxxx

x

xxxx x

x

xx

xxxxxxx

xx

xx

x$10

$20

$30

$40

$50

1970 1980

2.0%

2.5%

3.0%

3.5%

4.0%

5

1990 2000

$10

$20

$30

$40

$50

1970 1980

2.0%

2.5%

3.0%

3.5%

4.0%

Fraction of Proved R

eserves Used (per year)R

eal P

rice

of C

rude

Oil

(per

bar

rel)

xxx

x

x

xxx

x

x

xxxxx

xxxxx

x

xxxx

x

xxxx x

x

xx

xxx

xx

xxxxxxxxxxxx

xx

xx

xx

xx

xx

1990 2000These data are from BP Statistical Review of World Energy 2002.

the real or inflation-adjusted crude oil prices did not rise in proportion thus suggests that exhaustibility is as much a function of technology and price as of supply. Notice the estimates of 34.9 years for world’s future oil supply in 1971 and 38.6 years in 2001!

1971 641.80 18.40 102.03 34.9 1987 896.50 21.70 445.63 41.3

1972 672.70 19.30 121.33 34.9 1988 916.60 22.70 468.33 40.4

1973 635.00 21.10 142.43 30.1 1989 1011.80 23.20 491.53 43.6

1974 720.40 21.20 163.63 34.0 1990 1009.20 23.70 515.23 42.6

1975 666.10 20.10 183.73 33.1 1991 1000.90 23.10 538.33 43.4

1976 652.00 21.70 205.43 30.0 1992 1006.80 23.40 561.73 43.1

1977 653.70 22.90 228.33 28.5 1993 1009.00 23.40 585.13 43.1

1978 649.00 23.00 251.33 28.2 1994 1009.30 23.50 608.63 43.0

1979 649.20 24.00 275.33 27.1 1995 1016.90 23.80 632.43 42.8

1980 654.90 22.80 298.13 28.7 1996 1036.90 24.60 657.03 42.2

1981 678.20 21.60 319.73 31.4 1997 1040.00 26.22 683.25 39.7

1982 677.40 20.50 340.23 33.0 1998 1042.00 26.75 710.00 39.0

1983 677.70 20.30 360.53 33.4 1999 1044.00 26.22 736.22 39.8

1984 707.20 20.80 381.33 34.0 2000 1046.20 27.19 763.41 38.5

1985 707.60 20.60 401.93 34.4 2001 1050.00 27.18 790.59 38.6

1986 703.10 22.00 423.93 32.0 2002

Cumulative Production BBO

Number of Years

Remaining

Proved Reserves

BBO

Proved Reserves

BBO

Annual Production

BBO

Annual Production

BBO

Cumulative Production BBO

Number of Years

Remaining

Visit the WorldAtom site http://www.iaea.org/worldatom/ of

International Atomic Energy Agency for current news and

INTERNATIONALATOMIC ENERGY AGENCY

activities in the field of atomic energy

Radioactive minerals: – Three types of nuclear technology exist: fission technology

uses conventional (U235 -based) and breeder (U238 based) reactors while fusion technology, futuristic as yet, may eventually harness the limitless supply of heavywater: D2O.

–

Because of the differences in their half-life values, that for U238 ⇒ Pb206 decay being 4.5 Ga compared to 713 Ma for the U235 ⇒ Pb207 decay series, we have 33 times as much U238 as U235. This suggests that (a) initially, at the onset of nuclear synthesis, uranium is likely to have comprised equal amounts of U235 and U238, and (b) a shift to the U238 based technology should not only enhance mineral reserves for nuclear energy but also reduce the problem of waste disposal.

Other energy sources: these include geothermal, tidal, wind, OTEC (ocean thermal energy conversion), methyl hydrate gel etc. Discussions on earth resources can hardly be independent of the concerns about waste disposal, pollution, climate change, and the like geoenvironmental issues.

Browse Nuclear Energy Institute’s website http://www.nei.org/

23

Natural Disasters or the Earth Hazards Natural disasters are the environmental concerns amenable to geological evaluation and include – earthquakes and volcanism, – severe weather (floods, hurricanes, tornadoes), tsunamis, landslides, erosion, etc. and – extraterrestrial catastrophism, e.g., a bolide impact may have caused dinosaur extinction.

Natural disaster trends –

–

Since the 1970s, natural disasters have accounted for two-thirds of the disaster-related fatalities worldwide. Contrary to the common perception, earthquakes and volcanism have not produced most of these fatalities.

These fatalities seem more common in the economically less developed Third World, than in the economically developed countries, where their effect has been mostly as property losses. This makes the efforts at disaster mitigation a socioeconomic necessity.

Earthquakes: 8%

Floods: 19%

High winds: 20%

Drought & Famine: 6%

Volcanoes: 1%

Landslides: 3%

TotalFatalities

worldwide(1971-95)

= 8,219,000

Othernaturaldisasters: 9%

Man-madedisasters: 34%

0 4 8 12 16

ETHIOPIA

CHINABANGLADESH 31.9

SUDAN

48.4

DISASTER FATALITIES* (1971-95: IN THOUSANDS)

MOSTLY FLOODS

MOSTLY FAMINE

MOZAMBIQUE

MOSTLY MASS STARVATIONINDIA

SOVIET UNION/CIS STATES

IRANPHILIPPINES

NICARAGUA

COLUMBIAGUATEMALA

SOMALIA

NIGERIA

PERU

MEXICO

HONDURAS

* International Federation of Red Cross and Red Crescent Societies (The Economist, Sept 6, 1997)

D eathsD am age

(b ill 1996$)19901980197019601950194019301920

$19.1$21 .6$21 .0$13 .3

$5.0$5.1$1.8

1990198019701960195019401930192019101900

161226570750220

1050213010508100

Tw entie th C entury H urricane D estruction in the U .S .

Mitigation efforts: Natural disaster fatalities mostly follow an exponential scaling law that has a predictive value. Notice how all the fatality-frequency plots here display expo-nential decay (i.e., the fatal events are far fewer than the ones that are progressively less fatal). Clearly, disaster mitigation policies have to focus on either (a) increasing or (b) decreasing the slope of regression line here or (c) lowering the intercept!

The paradox of technology:

The environmental stress attendant to population growth has created a catch-22

Number of Fatalities per Event3 30 300 3,000

3

0.3

0.03

Tornadoes

FloodsTornadoesHurricanesEarthquakes

Num

ber o

f Eve

nts

per Y

ear

0.1

1

10

0.011 10 100 1,000 10,000

Floods

Hurricanes

Earthquakes

U.S. 20th Century Natural Disaster Fatality-Frequency Plots*

* S.P. Nishenko and C.C. Barton: “Scaling Laws for Natural Disaster Fatalities” inREDUCTION AND PREDICTABILITY OF NATURAL DISASTERS (Eds: Rundle,Turcotte and Klein) (Addison-Wesley, 1996)

situation: poverty and deprivation enhance environmental stress but the increasing recourse to technology needed to ameliorate this situation often ends up aggravating this stress.

Access this database on using satellite remote sensing for disaster mitigation efforts at

http://ltpwww.gsfc.nasa.gov/ndrd/

6

24

Nature and dimensions of the environmental crisis Dimensions and Premises of Environmental Debate

— The (a) human, technological and natural and (b) exhaustible, renewable and perennial dimensions of resources.

— Inelasticity of food demand versus technology’s degradation of environment. — Anthropogenic, biocentric and temporal streams of environmental concerns.

Some Environmental Perspectives: — Since population grows geometrically, while resources grow arithmatically, a

continued population growth is unsustainable (Thomas Malthus). — The invisible hands of supply and demand guide a freely competitive market to a

just and fair distribution of wealth (Adam Smith). — Earth provides enough for every person’s need but not for every person’s greed

(Mahatma Gandhi). — Nature, to be commanded, must be obeyed (Francis Bacon).

The exhaustibility of earth resources and the degradation of the environment are problems irrespective of whether we take — the Malthusian view that exhaustibility

limits economic growth; — the neo-Malthusian perspective that

resource exploitation has environmental limits; or

— the Ricardian perspective that progressive depletion raises costs and lowers quality;

This is particularly true when we note that — technology enhances efficiency but

degrades the environment, and — of all the natural disasters deleterious to

our habitat and environment, the climate

FranceU.K.

China

Sweden

Russia

USA

BrazilItaly

Singapore

0.1

1

10

100

0.01 0.1 1 10

Mexico

GermanyIndia Japan

NorwaySwtizerland

Saudi ArabiaNetherlands Australia

Spain

GDP (PPP) in trillion US $

Economic prosperity and energy consumption are closely correlated

Ene

rgy

cons

umpt

ion

(in te

rraj

oule

s) FranceU.K.

China

Sweden

Russia

USA

BrazilItaly

Singapore

0.1

1

10

100

0.01 0.1 1 10

Mexico

GermanyIndia Japan

NorwaySwtizerland

Saudi ArabiaNetherlands Australia

Spain

GDP (PPP) in trillion US $

Economic prosperity and energy consumption are closely correlated

Ene

rgy

cons

umpt

ion

(in te

rraj

oule

s)

related ones raise the most panic but promise the best prospects for mitigation. as is evident from these two graphs.

Our current environmental concerns therefore range from — geoenvironmental problems: from

global warming and air and water pollution to the degradation of coastal habitat; to

— geological problems: from predicting the earth hazards to solving the problems in foundation engineering and earthquake-proofing; and

0.03

0.1

1

3

0.1 1 10

0.3

30.30.03

USA

China

Japan

Russia

GermanyIndiaU.K.

UkrainePoland Canada

ItalyFrance

Iran

BrazilMexico

SouthKorea

Australia

SouthAfricaNorth

Korea

Kazakstan

...and so are economic prosperity and carbon emissions

GDP (PPP) in trillion US $

Tot

al C

arbo

n E

mis

sion

(b

illio

n to

ns)

0.03

0.1

1

3

0.1 1 10

0.3

30.30.03

USA

China

Japan

Russia

GermanyIndiaU.K.

UkrainePoland Canada

ItalyFrance

Iran

BrazilMexico

SouthKorea

Australia

SouthAfricaNorth

Korea

Kazakstan

0.03

0.1

1

3

0.1 1 10

0.3

30.30.03

USA

China

Japan

Russia

GermanyIndiaU.K.

UkrainePoland Canada

ItalyFrance

Iran

BrazilMexico

SouthKorea

Australia

SouthAfricaNorth

Korea

Kazakstan

...and so are economic prosperity and carbon emissions

GDP (PPP) in trillion US $

Tot

al C

arbo

n E

mis

sion

(b

illio

n to

ns)

– geoeconomic problems: from depletion of resources (energy, minerals, water and soil) to waste disposal.

7

25

STATE OF THE PLANET

THE FRAYING WEB OF LIFE

The new U.N. reportexamines the state ofknowledge about five majorcategories of ecosystems,scoring them in terms oftheir capacity to deliver thegoods and services thatsupport life and humaneconomies. It looks at howpeople have alteredecosystems and affectedtheir robustness, and wheretrouble might lie in thefuture.

-

FOREST

8

26