Geological History Study Guide (Mid-term)

Lesson #1

Objectives

Historical Geology - Principals and techniques of geology to reconstruct and understand the geological history of Earth.

Principal of Superposition of Strata - An Un - Deformed Stratigraphic Sequence, the Oldest Strata will be at the bottom.

Principal of Original Horizontality - Layers of sediment are originally deposited under the action of gravity.

Principal of Lateral Continuity - Layers of sediment extend laterally in all directions. Rocks are always similar. Separated by a valley or other erosional feature.

Uniformitarianism - Assumption that the same laws and processes that operate in the universe apply everywhere in the universe. Idea that earth has changed very little since the earth has changed very little from the beginning to the present time.

Principal of Faunal (Biological Succession) – Life forms of each age in the Earth’s long history were unique for particular periods, that the fossil remains of life permit geologists to recognize deposits around the world.

Principal of Cross Cutting Relationships – A rock that penetrates another body of rock must be younger than the rock mass penetrated.

Nicolaus Steno – Principal of Superposition - Any sequence of undisturbed strata, oldest layer is at the bottom.

James Hutton – Uniformitarianism – Physical and Chemical laws that govern nature are uniform. William Smith – Principal of Biological SuccessionGeorges Cuvier - Charles Lyell – Principals of geology, Principal of crosscutting relationships. Charles Darwin – Natural Selection. On species.

Standard Geological Timescale

Relative Dating - Determining the relative order of past events without determining absolute age.

Absolute Dating - Process where you determine the age on a specified time scale in geology. (Chronometric dating)

Role of Radioactivity

Questions;

1, 2, 3, 5, 8 – Pages 31

1. Describe the general steps used by geologists and other scientists in their attempt to solve particular problems or explain natural phenomena. `

A. QuestionB. HypothesisC. Test HypothesisD. Accept/Reject/Modify Hypothesis

2. Discuss the principals that Steno, Lyell, and Smith formulated for the development of the geologic time scale.

Steno – Superposition, original horizontality, and original lateral continuity.

Lyell – Principal of cross cutting relationships. Inclusions – Fragments within larger rock masses are older than the rock masses in which they are enclosed.

Smith – Principal of biological succession.

3. Explain the difference between a geochronologic term and a chronostratigraphic term.

Geochronologic term – Unit of time

Chronostratigraphic term – Body of rock deposited (Formed during a particular time interval).

Geochronologic units bear the same names as the Chronostratigraphic units to which they correspond.

5.What is meant by uniformitarianism? Cite an example of a process occurring on the Earth today that did not occur in the geologic past.

Uniformitarianism – Same geologic processes that operate in the universe have always operated in the universe

Which geologic process is occurring on the Earth today & did not occur in the past?

8. How do isotopes of a given element differ from one another in regard to number of protons and neutrons in the nucleus?

Isotopes are two or more varieties of the same element that have the same atomoic number and chemical properties but differ in mass numbers because they have a varying number of neutrons in the nucleus.

Lesson #2

1. Explain the difference between a rock and a mineral.

Mineral – Naturally occurring, inorganic substance. Definite chemical structure.

Contain multiple types of rocks.

Rock – naturally occurring aggregate of minerals and/or mineraloids. No definite

chemical composition.

2. Understand the nature and importance of silicate minerals (the most

abundant of the common rock-forming minerals).

90 Percent of the Earth’s Crust is composed of Silicates.

2. Visualize the important distinctions between six common silicate minerals:

quartz, feldspar, mica, hornblende, augite, and olivine.

Quartz – “ is a mineral that is most familiar and important of all the silicate minerals. It is common in many different families of rocks.”

Feldspar –

-- 60% of the total weight of the Earth's crust. -- They are both a 6-6.5 hardness and they cleave well in both directions.-- Pink or white-- White or gray

Two families:

- Orthoclase (potassium group)

- Plagiocase Group – Wide Range in Composition,

Feldspars are nearly as hard as quartz and range in color from white to pink or

bluish gray. They have good cleavage in two directions & the resulting flat, often

rectangular surfaces.

Mica – Family of silicate materials easily recognized by its perfect cleavage along

one directional plane.

Two chief varieties are the colorless or pale colored muscovite, and the dark

colored Biotite mica. (magnesium + iron).

Hornblende – Vitreous, black or very dark green material. Crystals tend to be

long and narrow.

Augite – Dark colored. Crystals are stumpy in shape, with good cleavages

developed along two planes that are nearly at right angles.

Olivine – Glassy looking iron/Magnesium silicate w/ and olive green color.

3. Describe four nonsilicate minerals that are also common in the earth’s

crust: calcite, dolomite, aragonite, and halite.

Calcite – Main constituent of limestone and marble. Secreted as skeletal material

by certain invertebrate animals, precipitated directly from sea water, or formed as

dripstone in caverns. Rhombohedrum-shaped cleaved fragments.

Dolomite – Carbonate Mineral CaMg(CO3)2 – rock largely composed of that

mineral.

Aragonite – Carbonate mineral that occurs in a different crystal form and more

rarely than calcite or dolomite. Inner “Mother of pearl” layer of clam shells.

Halite – Salty taste and fact that it crystallizes and cleaves to form cubes.

4. Describe the different origins of igneous, metamorphic, and sedimentary

rocks in the context of the rock cycle.

Igneous – Come from cooling masses of molten material that come from deep in

the Earth’s interior.

Metamorphic -

Sedimentary – Rocks composed of consolidated sediment – particles that are the

product of weathering and erosion of any previously existing rock or soil. The

components of sediment may range from large boulders to the molecules

dissolved in water.

5. Understand how igneous rocks are classified .

Intrusive//Plutonic – Igneous rocks that are formed from magma that had

penetrated into other Rocks and solidified before reaching the surface.

Extrusive/Volcanic – Form from melts that have reached the Earth’s surface.

Finer texture in which crystals are too small to be seen with the unaided eye.

6. Understand the essential difference between the two major families of

sedimentary rocks: clastic and carbonate.

Clastic – Fragments of pre existing materials that compose clastic sedimentary

rocks range in size from huge boulders to microscopic particles. Particle size is

particularly useful in classifying these rocks, which include conglomerates,

sandstones, siltstones, and shales.

Carbonate – Minerals that compose earth carbonate rocks including calcite,

aragonite, & dolomite.

7. Understand how metamorphic rocks are classified.

Foliated / Non Foliated.

Foliated -- Consisting of Thin Sheets

1, 2, 3, 4, 7, and 9

1. What is a mineral? What characteristics of a true mineral such as quartz or feldspar would not be present in a piece of glass?

Minerals are naturally occurring solid, inorganic substances that have a definite chemical composition or range of compositions as well as distinctive properties that reflect the composition and regular internal atomic structure.

2. What are the eight most abundant elements found in rocks and minerals?

1. Oxygen2. Silicon3. Aluminum 4. Iron5. Calcium 6. Sodium7. Potassium8. Magnesium

3. Why are silicate minerals important in geology? Which silicates might one expect to find in granite? Which silicates occur in sedimentary rocks?

Make up 90% of the Earth’s crust. (Rock forming minerals).

Granite is comprised of largely potassium feldspar, quartz, sodium plagioclase, hornblende, and mica.

In sedimentary rocks there are quartz, mica, and clay. .

4. Which igneous rock best approximates the composition of the continental crust? The oceanic crust?

Granite – Best Composition of the Continental Crust

Igneous Rock – Best Composition of the Oceanic Crust.

7. List the classic sedimentary rocks in order of increasingly finer grain size.

ConglomerateSandstoneSiltstone

ShaleClaystone.

8. List the foliated metamorphic rocks in order of increasingly coarser foliation.

SlatePhylliteSchistGneiss

Lesson #3

1. Explain the difference between the three structural (tectonic) elements of

the North American continent (shield, platform, and orogenic belt).

Shield – Large areas of exposed ancient crystal rock

Platform – Surrounding regions – where ancient rocks are covered by flat-

lying or gently warped layers of sedimentary rocks.

Orogenic Belt – Elongated Regions that border the Craton and have been

deformed by compressional forces since Precambrian time.

2. Discuss the three major depositional environments that exist on the earth

now and that existed in the geological past.

Marine Environment – \

Shallow Marine

Deep Marine

Continental Slope Environment s.

Transitional environment – Transitional environment between a marine and

non-marine environment. This is where deltas and familiar shoreline

accumulations of sand or gravel are located.

Deltas are present here – Accumulations of sediment formed by the entrance of

a stream into quiet water such as the ocean or a lake.

Deltaic sediments are rich in organic debris and include many alternating and

intersecting bodies of permeable sands and impermeable clays.

Includes barriers, lagoons that lie between the barrier islands and mainland (tidal

flats).

Continental environment – Deposition includes river floodplains, alluvial fans,

lakes, glaciers, and Eolian (wind) environments.

Eolian Environments – Area where wind is an important agent of sediment

transport.

3. Outline the significance of color, texture, and sedimentary structures in

determining the environment of deposition for any given sedimentary rock.

Color –

Black – Usually results from the presence of compounds containing organic

carbon. May contain large amounts of H2S.

Red – As a result of iron oxide content. Occurs in oxygen – deficient

environments. Unstable and may oxidize to form ferric iron oxide.

Red Beds – Strata that is colored Red, Brown, or Purple by ferric iron are

designated red beds. Associated rocks and sedimentary structures.

May be a product of source materials, may have developed after burial, or

may be the result of subsurface alteration, or Sub Aerial oxidation.

Texture –

Matrix – bonding material that consists of Finer Clastic particles that were

deposited at the same time as the larger grains that fill the crevices between

them.

Cement – Chemical precipitate that crystalizes in the voids between grains,

following deposition. Fine carbonate muds are not likely to settle to the bottom of

turbulent water.

Stronger current of water (or wind) is required to move a large particle than to

move a small one. Therefore. Stronger wind == more particles. Wind sweeps

finer particles into the higher regions of the atmosphere.

Shape – (Rounding and Sphericity). A particle becomes rounded by having sharp

coners and edges removed by impact with other particles. The roundness of a

particle can be used to infer the history of abrasion. It is a reflection of the

distance the particle has traveled, the transporting medium, and the rigor

of transport.

Arrangement

The arrangement can help to determine if the sediment had been winnowed and

sorted by currents or had been dumped rapidly. Sand grains deposited in water

currents acquire a preferred direction that align according to the direction of flow.

Direction of movement in glaciers – can provide clues to the subsurface

location and trend of petroleum bearing sandstone strata.

Structures

Larger features of sediments that are formed during or shortly after deposition

and before Lithification.

Mud Cracks – Indicate drying after deposition. Conditions are common on valley

flats and in Tidal Zones.

Cross-Bedding – is an arrangement of beds of lamination in which one set of

layers is inclined relative to the others. Tells a story of a depositional environment

dominated by currents (Wind or Water) Direction of the inclination of the sloping

beds is useful to tell the direction of the current.

Graded Bedding – Repeated beds, each of which has the coarsest grains at the

base and successfully finer grains nearer the top. Appears to be a big

characteristic of turbidity currents (often triggered by submarine earthquakes

and landslides that occur along steeply sloping regions of the seafloor. Turbidity

currents frequently characterize unstable, tectonically active environments.

Ripple Marks – Formed by air or water currents.

4. Indicate the major differences between clastic sedimentary rocks

(sandstone, shale, conglomerate) and carbonate sedimentary rocks

(limestone).

The two main families of sedimentary rocks are clastic and carbonate. Both types are important and abundant. They form, however, by different means. Clastic rocks (sandstones, siltstones, shales, and conglomerates) form when weathered material (quartz grains, felspar grains, mica flakes, rock fragments, and so forth) is brought from a sediment source area to a basin of deposition by streams, glaciers, or wind. Texture and sedimentary structures indicate conditions within the basin of deposition, while the clastic rock's composition reflects the nature of the sediment source area, which may be located hundreds of miles from the final resting place of the sediment. Consider that the Mississippi River delta receives sediment from areas as far away as the Rocky Mountains. While in transit, these sedimentary particles are rounded, sorted, and chemically altered. // Clastic rocks are classified by texture and composition. Classification begins with assessing particle size. If grains comprising a rock are larger than 2 millimeters in diameter, the rock is diagnosed as a conglomerate. If sedimentary particles fall between 1/16 and 2 millimeters, the rock is called a sandstone. Siltstone and shale are comprised of even smaller grains. Sandstones have been further subdivided based on the mineralogy of the constituent sedimentary grains. Sandstones dominated by quartz grains are simply called quartz sandstones. These sandstones are compositionally mature in the sense that they lack unstable mineral grains (mica, feldspar, and so forth) and are relatively well sorted. Since only durable quartz is present, these rocks suggest deposition only after a long period of sediment alteration and transport. Pinkish or reddish sandstones containing abundant feldspar (>25 percent) reflect deposition in close proximity to a granitic (feldspar rich)

source region. Such sandstones are called arkoses. A third type of sandstone, known asgraywacke, is a poorly sorted sandstone, containing up to 30 percent clay material. Quartz is typically present, but so is a host of unstable silicate minerals such as mica, chlorite, feldspar, and volcanic rock fragments. // By contrast, limestone (the most important carbonate rock) is comprised of biologically produced carbonate grains (mainly calcite and aragonite) in the form of shells and carbonate muds that accumulate in clear, warm, shallow seawater (and to a much lesser degree in lakes). Unlike the grains in a sandstone, those comprising carbonate rocks are produced in the basin of deposition in close proximity to their final resting place by organic activity. Little if any transportation, with its concomitant sorting and rounding, takes place. Because the grains are both formed and buried in the same area, they are sensitive indicators of past environments.

5. Understand the concept of lithostratigraphy (subdivision of the rock record

into formations, members, and so on).

Lithostratigraphic Units – Bodies of rock identified by their distinctive

lithologic and structural features w/ no regard to time boundaries.

Mappable units and are distinctly different from the time-rock or

Chronostratigraphic Units defined in the previous chapter.

6. Explain the concept of sedimentary facies.

Facies – Refers to the characteristic aspects of a rock from which its environment

of deposition can be inferred.

7. Summarize the origin and significance of sea-level changes in the

sedimentary rock archive.

Figure 3-42 (page 87 of your textbook) shows the pattern of sea-level oscillation over the last 600 million years of Earth's history. Note that the red line represents modern sea level. The blue line represents the position of sea level at any given point of time during the last 600 million years (Cambrian to Recent). When the blue sea-level curve is left of the red line, it indicates a time when sea level was higher than its present level. The blue sea-level curve is right of the red line when sea level is lower than at present. Four important observations emerge from this diagram: (see next cards.)

8. Clarify the differences between a nonconformity, angular unconformity,

and disconformity.

Unconformity – break in stratigraphic continuity.

Nonconformity – Surfaces where stratified rocks rest on older intrusive igneous

or metamorphic rocks.

Angular Unconformity – Break in stratigraphic continuity. One of the layers

is angled towards the first one.

Disconformity – Parallel Strata separated by an erosional surface.

Go back and familiarize yourself with the terms in italics. Answer review questions 1, 2, 3, 5, 6, and 7.

1. What features in a sedimentary rock might indicate it was deposited in

each of the following environments of deposition?

a. Shallow Marine Environment – Tends to be coarser than deeper rock,

also tends to be bigger (small rocks are carried off to sea)

b. Deep Marine, Continental Rise Environment – Very Fine Clay, Volcanic

Ash, and the calcareous or siliceous remains of microscopic organisms

settle to the ocean floor. Sporadic occurrences of coarser sediments.

c. Transitional, Deltaic Environment – Rich in organic debris, include

many alternating and intersecting bodies of permeable sands and

impermeable clays.

d. Continental, desert environment – Silt and Clay. Unsorted mixtures of

boulders, gravel, sand, and clay

2. Why are sandstones and siltstones of desert environments rarely black

or gray in color?

The black and grey color results from the presence of compounds containing

organic carbon and iron. The conditions that make the black or gray colors

possible are rare (organisms that are breaking down).

3. How does a matrix in a rock differ from cement? What are the most

common kinds of cements?

A matrix fills the crevices between the larger pieces of rock. Finer particles

were deposited at the same time during deposition.

Cement crystallizes the voids between grains following deposition. Silica and

Calcium Carbonate are natural cements.

5. What differences in texture and composition serve to distinguish

between mature and immature sandstone?

The higher the percentage of quartz, greater the maturity.

Mature Sandstone – More rounding and sorting than the immature sandstone.

Immature Sandstone – A sandstone rich, less-durable and angular components

that underwent relatively little transport and other forms of geologic duress.

6. In a columnar section of sedimentary rocks, a limestone is overlain

by shale, which in turn is overlain by sandstone. What might this

coarsening upward sequence indicate with regard to the advance or

retreat of the shoreline?

The limestone represents deposition furthest from shore, the shale represents deposition closer to shore, and the sandstone represents deposition at the shoreline. The vertical succession reflects an upward transition from offshore Limestone to Nearshore sandstone; thus, the water was becoming increasingly shallow as the rock column was deposited. This would reflect the retreat of the shoreline towards the ocean (regression).

7. What conditions in the Bahama Banks carbonate platform result in

the high production of calcium carbonate sediment?

The main condition required for the development of a Bahama-like carbonate platform is clear, warm, shallow seawater. Carbonate production is so prolific in the Bahamas because there are no rivers dumping clay and sand into the region. As a result, the waters are quite clear. The top of the carbonate platform is covered with nutrient-rich water that is no deeper that thirty or forty feet, well within the photic zone. Since it is located at low latitudes, surface water is warm. The warm, clear water promotes production of marine plants and algae, which in turn support a prolific community of carbonate-secreting invertebrates that, upon death, donate their shells to the growing layer of seafloor sediment.

Lesson #4

1. Define the term fossil and understand the following types of fossil

preservation: recrystallization, replacement, carbonization, and

permineralization.

Recrystallization – Less stable hard part Mineralogies are transformed, through

void time, by temperature and pressure to more stable minerals. The

replacement however is not destructive. Much of the original material still

remains.

Replacement – Exchange of the original substance with a mineral matter of a

different composition. Old material is replaced with new material of equal volume.

Carbonization – Occurs when soft tissues are preserved as thin films of carbon.

Premineralization – The addition of a chemically precipitated substance into pore

spaces.

2. Discuss the completeness of the fossil record.

The fossil record of life is incomplete. Only a limited number of plants and

animals have been preserved. Fossil record is extremely comprehensive

considering the many factors that can destroy fossils.

More complete for land life lacking bone or shell.

3. Indicate the role of fossils in establishing the age equivalence of

sedimentary strata.

Because of the change in life through time, superposition, and the observation

that once species have become extinct they do not reappear in later ages, fossils

can be used to recognize the approximate age of a unit and its place in the

stratigraphic column.

The interval between the first and last appearance of a species constitutes the

geologic range.

4. Explain how fossils are used to reconstruct ancient ecosystems, climates,

and geographies

The chance inability to find key fossils might lead to erroneous interpretations.

“Two or three million years from now, geologists might have difficulty in firmly

establishing on fossil evidence that the North American opossum, the Australian

wallaby, and the African aardvark lived during the same episode of geologic time.

However, if they found fossils of Homo Sapiens with each of these animals, it

would indicate their contemporaneity.

Homo Sapiens can be considered the cosmopolitan species, for it is not

restricted to any single geographic location.

The aardvark and wallaby are said to be endemic species in that they are

confined to a particular area.

Answer review questions 1, 2, 3, 4, and 11 on page 146 of the textbook,

1. What factors determine whether or not a particular fossil will be valuable

as an indicator of the age and correlation of a stratum?

Cosmopolitan species have been especially useful in establishing the

contemporaneity of strata, whereas endemic species are generally good

indicators of the environment in which strata were deposited.

2. Fossil A occurs in rocks of Cambrian and Ordovician age. Fossil B

occurs in rocks that range in age from early Ordovician through Permian.

Fossil C is found in Mississippian through Permian Strata .

a. What is the maximum possible range of age for a stratum containing

only fossil B?

Early Ordovician through the Permian

b. What is the maximum possible range for a stratum containing both A

and B?

Ordivician

c. Which is the better guide fossil, A or C?

a. Silurian and Devonian, Ordovician, This is difficult to evaluate given the scanty data. A would be a better guide fossil than C for Cambrian and Ordovician rocks and vice versa.

3.A chronostratigraphic (time – rock) unit contains a different fossil

assemblage at one locality than another located 200km away. Suggest a

possible cause for the dissimilarity.

The species are endemic, and both areas have different creatures that lived

during that period of time.

Additionally, the animals or flora may have simply moved.

4. In drilling for oil, geologists recover Devonian conodonts in a stratum

known to be Permian in age. Exlain how this may have occurred.

The Conodonts may have been a reworked fossil. Weathering and erosion have

freed fossils from their host rock. The fossils may then work their way into

younger beds, & the younger strata might be mistakenly assigned to an older

geologic time.

11. Using fossils for age correlation is dependent on a priori knowledge of

their age ranges. How has this knowledge been obtained?

This knowledge has been obtained through carefully observing fossil occurrences in rock layers during the last 200 years. For example, dinosaur bones have been found in Mesozioc rocks, but to date, no dinosaurs have been found in Paleozoic rocks. Similarly conodonts have been found in late-Cambrian, Ordovician, Silurian, Devonian, Mississippian, Pennsylvanian, Permian, and Triassic strata. They have not been found in Jurassic or younger formations, in spite of efforts to find them there.

Lesson #5

1. List the subdivisions of the Linnean classification scheme in their proper

order.

Five Kingdoms:

Monera

Proctoctista

Plantae

Animalia

Fungi

2. Indicate the difference between biological species and paleontological

species.

Biological Species -- Group of individuals which can breed together (panmixia)

Paleontological Species -- Group who’s members are descended from a common ancestor.

3. Discuss Lamarck’s theory of evolution.

All species, including humans, are descended from other species.

4. Explain the concept of natural selection.

Descendants of former creatures have undergone biologic change and are

different from their ancestors.

5. Briefly discuss evolution in terms of modern genetics.

Mutations, Gene Recombination, and Natural selection help run modern organic

evolution.

6. Contrast phyletic gradualism and punctuated equilibrium.

Phyletic Gradualism – Gradual progressive change. Refers to evolutionary

pathways. Evolutionary change occurs by slow degrees along the evolutionary

pathway of a lineage.

Punctuated Equilibrium – Evolution that consists of fitful sudden advances that

punctuate long episodes of little evolutionary progress – and then periods of

“stasis”, where there is little evolution if any at all.

7. Understand Charles Darwin’s role in the development of modern

evolutionary theory.

Answer review questions 6, 7, 8, 10, and 12 on page 146 to the best of your

ability. 

6. What are the differences between the following?

Mitosis/Meiosis –

Meiosis – Two quickly succeeding divisions to produce four final daughter cells.

Mitosis – Process of cell division that produces new diploid cells with exact

replicas of the chromosomal components with the parent cells.

Haploid/Diploid

Haploid – Does not have paired chromosomes

Diploid – Has paired chromosomes

Gymnosperm/Angiosperm

Gymnosperm – Vascular plant that produces seeds lacking an outer fruit.

Angiosperm – Flowering plants that reproduce through seeds that are contained

in fruit.

Stratophenetic/Cladistic Phylogeny

Stratophenetic Phylogeny – Organisms are arranged in a treelike fashion, with

the most recently evolved species or groups on the upper branches or older,

ancestral species on the lower branches and trunk.

Cladistic Phylogeny – Organisms are analyzed objectively on the basis of

characteristics they share in order to determine their ancestor – descendant

relationships

Domain/Kingdom

Domain – Two+ Kingdoms

Kingdom – Large group of related phyla (group of similar creatures)

7. What is meant by the term adaptation? Cite an example of adaptive

radiation.

The branching of a population to product descendants adapted to particular

environments and living strategies.

The honey creepers of Hawaii. The birds are believed to have evolved from a

common ancestor, from there each bird evolved on it’s own. All of the birds have

a different adaptation.

8. What are peripheral isolates?

Sudden change that interrupts equilibrium occurs at the periphery.

Segments of the population are referred to as peripheral isolates.

10. What are the contributions of Darwin and Mendel to our modern

concept of organic evolution?

Darwin Theory of Natural Selection. Those better fitted to their environments

will thrive.

Mendel discovered the basic principals to inheritance. Mendel described the

mechanism in which traits are transmitted from adults to offspring. Modern

version of “genes”

12. Distinguish between the concepts of phyletic gradualism and

punctuated equilibrium. How did Charles Darwin account for the rapid or

abrupt appearance of new species? Which, then, would be a more

appropriate geologic section to study for proof of punctuated equilibrium.

-- continuous set of cores from the floor of the ocean, or a section on the

continent where there has been repeated episodes of uplift and erosion

throughout geologic time.

Phyletic Gradualism – Gradual progressive change (evolutionary pathways)

Punctuated Equilibrium – Evolution that consists of fitful sudden advances that

punctuate long episodes of little evolutionary progress termed stasis.

Darwin insisted that the transitional forms once existed but were not preserved,

were destroyed, or had not yet been discovered.

Repeated episodes of uplift and erosion through geologic time is a better place to

study.

Lesson #6

1. Understand the fundamental properties of primary, secondary, and surface

seismic (earthquake) waves and indicate how primary and secondary

waves are used to image the Earth’s internal layering.

Primary Waves – Fastest of the waves and the first to arrive at a seismographic

station after there is an earthquake. Upper crust of Earth at 4 – 5 km/sec. Near

the base of the crust at 6-7 km/sec. First to show on seismogram.

Pulses are transmitted in such a way that the movement of rock particles is

parallel to the direction of propagation of the rock itself. Alternations of

compressions and expansions that speed away from the source of shock. “Push

– Pull movement” that can be transmitted to solids, liquids, and gases.

Secondary Waves – S – Waves, transverse waves. 1-2 km/sec slower than P-

Waves. Movement of rock particles is at right angles to the direction of

propagation of the energy. Do not pass through liquids or gasses. Second to

show on seismogram.

Both are termed body waves because they are able to penetrate deep into the

interior or body of our planet. Travel faster in rocks of greater elasticity, and their

speeds increase steadily as they move downward into the more elastic zones of

the Earth’s interior.

Fluid w. no rigidity. S-Waves cannot propagate and P-Waves are markedly

slowed.

Surface Waves – large – motion waves that travel through the outer crust of the

Earth. Their pattern of movement resembles that of waves caused when a

pebble is tossed into the center of a pond. Last to arrive at a seismographic

station. Destruction results because surface waves are channeled through the

thin outer region of the Earth & energy is less rapidly dissipated into the large

volumes of rock traversed by body waves.

2. Briefly describe the properties of the inner core, outer core, mantle, and

crust and indicate the role of seismic discontinuities (Mohorovicic and

Gutenberg) in locating the boundaries between these layers.

Discontinuities:

Mohorovicic – Observations that seismograph stations located about 150km

from an earthquake received earthquake waves sooner than those nearer to the

focus. Reasoned that below a depth of about 30km there must be a zone

having physical properties that permit earthquake waves to travel faster.

That layer is the upper mantle. (between crust and mantle)

Gutenberg – Located nearly halfway to the center of the Earth at a depth of

2900 km. It’s location is marked by an abrupt decrease in P-wave velocities and

the disappearance of S-waves caused by a change in composition. It is the outer

boundary of the Earth’s core.

Inner core – Scientists believe that the inner core has the same composition as

the outer core, and it only exists as a solid because of the enourmous pressure

at the center of the Earth. Solid. Certain wave patterns that could only be

explained by assuming that the inner core behaved seismically as if it were solid.

Estimated to be around 85 percent iron and lesser parts nickel.

A magnetic field is developed by the flow of electric charges and requires good

electrical conductors.

Shadow zone – Areas where S Waves do not appear.

Outer Core – See inner core.

Mantle – Stony, metallic, composition. Oxygen and silicon dominate and are

accompanied by iron and magnesium as the most abundant metallic ions. Rich in

Olivine + pyroxene.

Multiple Layers:

- Asthenosphere - High in the upper mantle. Rock in the asthenosphere is

at or near its melting point & some magmas are generated in this zone.

Seismic waves slowed.

- Lithosphere – includes crust, and the uppermost part of the mantle.

Dynamic enveloping shell of the Earth and is itself divided into lithospheric

plates.

Dynamic enveloping shell of the Earth and is itself divided into many lithospheric

plates.

Crust – All of the solid Earth above the Mohorovicic discontinuity. Thin, brittle

veneer that constitutes the continents and floors of the oceans. The crust is not a

homogeneous shell. 2 distinct kinds of crust.

Oceanic Crust – Beneath ocean floors.

Continental Crust – Boundaries of ocean basins. Thicker than oceanic

counterpart but less dense. Isostasy – Segments of the Earth’s crust as they

come into floatation equilibrium with denser mantle material. Explains why

continental crust stands higher than the oceanic crust.

3. Indicate the basic properties that distinguish oceanic crust from

continental crust.

Oceanic Crust – 3 Layers. Upper surface – thin layer of unconsolidated

sediment that rests on the irregular surface of the igneous basement layer

2nd- Basalts that had been extruded under water.

3rd. Nature of the deepest layer of oceanic crust is not clear.

Iron, Magnesium, Calcium.

Continental Crust – Thicker and less dense than the oceanic crust. Continents

“float” higher on a denser mantle then the oceanic crust sediments.

Isostasy – Segments of Earth’s crust as they come into equilibrium with a denser

mantle. Continental crust stands higher than the denser oceanic crusts.

4. Define fault and indicate how a given fault is classified as normal, reverse,

or strike-slip.

Normal fault – Hanging wall appears to moves downward relative to the

opposite side or foot wall.

Reverse fault – exhibit a hanging wall that has moved up relative to the foot

wall

Strike Slip -

5. Discuss the differences between anticlines, synclines, domes, and

basins.

Anticline – Unparched rocks in which the oldest rocks are in the center and

the youngest rocks are on the flanks.

Syncline -

Domes -

Basins -

6. Explain the types of evidence presented by Alfred Wegener that supports

his theory of continental drift.

7. Explain the concept and applications of paleomagnetism.

Paleomagnetism – Study of the record of the Earth’s magnetic field in rocks,

sediment, or archeological materials. Certain minerals in rocks lock in a record of

the direction and intensity of the magnetic field when they form.

1. Finding the direction of the poles .

2. Can be used to determine the latitude at which an igneous body

containing magnetic minerals cooled and solidified.

8. Concisely define the concept of seafloor spreading.

Seafloor Spreading – The process by which new oceanic crust is produced at

mid oceanic ridges and moved laterally away from the ridge.

9. Describe the three types of plate margins (convergent, divergent, transform

fault) and identify what types of geological activities, geological structures

(folds and faults), and rocks occur at each.

Plate margins:

Convergent: Develop when two plates move toward one another and collide.

These junctions are characterized by a high frequency of earthquakes. In

addition, they are the zones along which compressional mountain ranges or deep

sea trenches may develop.

One plate may slip and plunge below the other, producing a subduction zone.

Divergent: May manifest themselves at mid - oceanic ridges complete with

tensional geological structures. The mid-Atlantic ridge approximates the line of

separation between the Eurasian and African plate on one side and the American

plate on the other. As is to be expected, such a rending of the crust is

accompanies by earthquakes and enormous outpourings of volcanic materials

that are piled high to produce the ridge itself.

Transform Fault: The line along the mid-oceanic ridge where spreading begins

is not straight or smoothly curving & is offset by numerous faults.

Geological activities Geological structures --

10.List several lines of evidence that support the plate tectonic theory.

Simple concept. Movement of the plates causes them to converge, diverge, or

slide past one another. Results in frequent earthquakes along plate margins.

When the locations of earthquakes are plotted on the world map, they clearly

define boundaries of tectonic plates.

11.Speculate upon the fundamental causes of plate motion.

Answer questions 1, 2, 4, 5, 8, 11, 13, 14, and 16 on pages 194 and 195 of the textbook. 

1. If one were able to drill a well from the North Pole to the center of the

earth, what internal zones would be penetrated?

Solid Inner Core, Liquid Outer Core, Mantle, Crust

2. What are the three major categories of seismic waves? Describe their

characteristics.

Primary – Fastest of the waves, First to arrive at a seismograph station.

after there has been an earthquake. Travel through the upper crust of the Earth

at speeds of 4 to 5 km/s. Pulses of energy are transmitted in such a way that the

movement of rock particles is parallel to the direction of propagation of the rock

itself. A given particle of rock set in motion during an earthquake is driven into it’s

neighbor and bounces back.

Secondary – S waves or transverse waves. Travel 1 to 2 km/sec slower than P

waves. Movement of rock particles is secondary waves is at right angles to the

direction of propagation of the energy. More complex motion, so they travel

slower. Will not pass through liquids or gasses (unlike P Waves).

Surface Waves – Large motion waves that travel through the outer crust of the

Earth. Their pattern of movement resembles that of waves caused when a

pebble is tossed into the center of a pond. Develop whether P or S-waves disturb

the surface of the Earth as they emerge from the interior. Last to arrive at a

seismograph station. Primary cause of destruction from an earthquake.

Destruction results because surface waves are channeled through the thin outer

region of the earth. & their energy is less rapidly dissipated into the large

volumes of rock traversed by body waves.

3. What is a seismic disconuity? Hat are the Gutenberg and

Mohorovicic discontinuities located?

Mohorovicic – Observations that seismograph stations located about

150km from an earthquake received earthquake waves sooner than those

nearer to the focus. Reasoned that blow a depth of about 30km there

must be a zone having physical properties that permit earthquake

waves to travel faster. That layer is the upper mantle. (between crust

and mantle)

Gutenberg – Located nearly halfway to the center of the Earth at a depth

of 2900 km. It’s location is marked by an abrupt decrease in P-wave

velocities and the disappearance of S-waves caused by a change in

composition. It is the outer boundary of the Earth’s core.

Seismic Disconuity – A surface which velocities of seismic waves change

rapidly. See above for the two different discontinuities.

5. How to anticlines (and domes) differ from synclines (and basins) with

regard to the age relations of rocks exposed across the erosionally

truncated surfaces of these structures?

The limestone represents deposition furthest from shore, the shale represents deposition closer to shore, and the sandstone represents deposition at the shoreline. The vertical succession reflects an upward transition from offshore limestone to nearshore sandstone; thus, the water was becoming increasingly shallow as the rock column was deposited. This would reflect the retreat of the shoreline towards the ocean (regression).

9. What are the principal categories of faults? What kinds of faults might

one find in regions subjected to great compressional forces? What kinds of

faults result primarily from tension in the Earth’s crust?

Normal, reverse, transform. Reverse faults predominate in regions subjected to compressional stresses. Normal faults are formed in response to tensional stresses.

12.Compile a list of items that Alfred Wegener might have used to

convince a skeptic of the lidity of his theory of continental drift.

Argued for the existence in the past of a supercontinent that de dubbed Pangea.

That portion of Pangea that was to separate and frm North America and Eurasia

came to be known as Laurasia, whereas the southern portion retained the earlier

designation of Gondwanaland. Pangea was surrounded by a universal ocean

named Panthalassa, which opened to receive shifting continents when they

began to split apart 200 years ago.

Correspondence is too good to be fortuitous, even when considering the

expected modifications of shorelines resulting from erosion, deformation, or

intrusions following the break-up of Pangea around 200 million years ago.

Sedimentologic criteria indicating similarity of climatic conditions for widely

separated parts of the world. Locations of such coal deposits should approximate

an equatorial zone relative to the ancient pole position for that age.

Many of the geologic features almost perfectly correspond to how the Earth

moved.

Fossil records give important evidence.

Character,sequence, age, and distribution of rock units have also been examined

for insights into the concepts of drift.

13. According to plate tectonics, how did the Himalaya mountains form?

The San Andreas fault? The Dead Sea and Red sea?

Each of these reflects a different type of plate margin interaction. The Himalayas are the result of India colliding with Asia (convergent plate margin). The San Andreas Fault is a transform fault (passive margin) between the North American plate, which is moving south, and the Pacific plate, which is moving north. Finally, the Dead Sea and Red Sea occupy depressions resulting from the early stages of rifting (divergent plate margin).

14. According to plate Techtonics, where is new material added to the sea

floor, and where is older material consumed?

New oceanic crust is generated at spreading centers (Midocean ridges) and destroyed at Subduction zones.

16. What is remanent magnetism? What is its origin? How is it used in

finding ancient pole positions? How has remanent magnetism helped

validate the concept of plate techtonics?

Remanent Magnetism – Magnetism frozen into ancient rocks.

When igneous rocks cool past the Curie temperature (temp above where

substance is no longer magnetic) of their magnetic Mineralism. Some of the

magnetism remains from earlier times.

Remnant magnetism in a mineral is ultimately due to the fact that some atoms

and ion have so called magnetic moments (they behave like tiny moments). Iron

ions align themselves within the crystal lattice so that their magnetic moments

are parallel.

When magnetite takes on its Remanent magnetism, the iron ions align

themselves within the crystal lattice so that their magnetic moments are parallel.

(Ancient pole positions)

Lesson #7

1. Define red shift in the context of the big bang theory.

Red Shift – If a star is moving away from the Earth, Wavelengths of the light from

the star are shifted toward the red end of the spectrum. The greater the velocity

of separation, the wider the observed red shift. Additionally, further away the

Galaxy (means further velocity of separation), the wider the red shift.

2. Explain the main idea behind the solar nebula hypothesis.

Solar Nebula Hypothesis – A favored hypothesis is that the solar system was

derived from a rotating cloud of dust particles called the solar nebula.

Cold, rarefied cloud of gasses and dust particles. Initial material consisted of

elements and the chemical compounds formed by combinations of elements.

Formed by combinations of elements. Elements forming the cloud were originally

produced by nuclear reactions within stars or by great explosions that mark the

death of stars.

Dust cloud went in a counterclockwise direction, to contract, and to assume a

Discoidal shape.

3. Explain the origin and evolution of Earth’s oxygen-rich atmosphere.

Solar winds blew the primordial atmosphere into space. Hence, the modern atmosphere was formed from scratch, largely through volcanic outgassing. In the early Precambrian, this nascent atmosphere was comprised of methane, ammonia, and carbon dioxide. The modern oxygen-rich atmosphere evolved through photochemical dissociation of water vapor and, once life evolved, from photosynthesis.

4. Discuss the duration and order of eons comprising the Precambrian

interval.

Order – Duration (In billions of years)

Late Proterozoic – 0.46

Middle Proterozoic – 0.6

Early Proterozoic – 0.9

Late Archean – 0.5

Middle Archean – 0.4

Earch Arvhean – 0.4

Hadean – 0.8

5. Articulate the differences between the terms shield , craton , and platform .

Shield – Broadly unwarped, geologically stable regions of continents called

shields. Every continent has one or more shields.

Craton – The platform of a continent plus it’s shield constitutes the continent’s

Craton.

Platform – Stable regions where basement rocks are covered by relatively thin

blankets of sedimentary strata.

(See below)

6. Explain the origin of the Precambrian provinces of North America shown

on figure 6–17 of the text.

Canadian shield has been divided into a number of Precambrian Provinces,

Boundaries of these provinces are often marked by abrupt truncations in

structural lineations, or they may be represented by bands of severely deformed

rocks of former orogenic belts.

They were once separate crustal segments that have been consolidated to form

the larger north American Craton. Bound together by belts of deformed,

Metamorphed, and intruded rocks that mark the location of collision of the

various Cratonic elements.

7. Indicate the significance of Stanley Miller’s experiments to theories about

spontaneous generation of life on Earth.

Stanley Miller infused an atmosphere at that time thought to be like Earth’s early

atmosphere.

The experiment showed that life began to form with only the gasses in the

Earth’s atmosphere. Supporting the idea of spontaneous generation of life on

Earth.

8. List the major fossils of the Precambrian and explain the differences

between prokaryotic and eukaryotic organisms.

BANDED IRON, STROMATOLITES, ARCHAEA CELLS, DICKINSONIA, ETC.

differences between prokaryotic and eukaryotic organisms: prokaryotic organisms do not have a nucleus and eukaryotic organisms do. Eukaryotic DNA is linear; prokaryotic DNA is circular (it has no ends)

9. List evidence for Earth’s first glacial episode (Gowganda formation).

Glacial sediments of the Gowganda formation indicate that glaciers covered the region north of modern Lake Huron during early Proterozoic time.

10.Discuss the nature and significance of banded iron formation (BIF).

Banded iron formations are marine sedimentary rocks consisting of alternating

thin layers of red iron oxides and grayish chert. Proterozoic banded iron

formations are typically hundreds of meters thick and can be regionally

extensive.

Most important source of iron ore. 92 percent were deposited during the early

part of the Proterozoic eon between 2.5 and 2 billion years ago. Earlier they did

not occur abundantly because oxygen was not yet sufficient in the atmosphere

and ocean. Later they did not occur abundantly because by then free iron had

been swept from the oceans by the early Proterozoic BIF forming event. They

represent a unique interval in the chemical coevolution of Earth’s atmosphere,

hydrosphere, and lithosphere.

11.Describe the fossil record of the Proterozoic eon, including proliferation of

stromatolites, appearance of eukaryotes, and evolution of the first

multicellular animals.

During the Proterozoic, Stromatolites proliferated and covered the floors of the extensive Cratonic ocean, thereby generating the oxygen that forced the deposition of BIFs. By middle Proterozoic time (1.6 billion years ago) single-celled eukaryotes appeared with their capacity for sexual reproduction. In late Proterozoic time the first multicellular animals (Ediacaran Fauna) evolved.

2. What is the source of the sun’s heat? Given the amount of solar radiation intercepted by the Earth, why is the Earth’s surface not hotter than it is?

The sun’s heat comes from nuclear fusion of hydrogen atoms into atoms of helium.

The Earth has experienced differentiation, a process whereby a planet becomes internally zoned or layered.

Radiation is reflected back to space. Another part of the incoming radiation is absorbed by the atmosphere and radiated back into space.

Another part of the incoming radiation is absorbed by the atmosphere and radiated back into space.

3. What evidence indicates that the universe is expanding?

The spectral signatures of galaxies are red shifted. The red shift indicates that the galaxies are moving away at incredibly fast speeds.

13.Distinguish between the terms Precambrian shield, craton, and platform.

Shield – Extensive area of continent where Precambrian igneous and metamorphic rocks are expose and have been eroded to a nearly flat surface close to sea level

Craton – Platform + Shield compose the Craton

Platform – Similar to the shield, except the Precambrian rocks have been covered with layers of sedimentary rock.

12.What geologic evidence suggests that free oxygen was beginning to accumulate in the Earth’s atmosphere about 3 billion years ago?

Banded iron formations are important as a source of iron and as an indicator of atmospheric evolution. Banded iron formations are special sedimentary rocks comprised of alternating layers of iron rich and iron poor layers. The fact that the iron in banded iron formation was weakly to strongly oxidized indicates that oxygen was beginning to accumulate in the environment at that time.

13.Discuss the role of symbiosis in the evolution of eukaryotes. What organelles may have originated by symbiosis?

Suggests that the nucleus and well-ordered genetic material in a eukaryotic cell may have arisen through ingestion, not digestion, of one prokaryotic cell by another. Through time the ingested cell was modified into the chloroplast and mitochondria of the typical Eukaryote

5. How to eukaryotes differ from prokaryotes (see chapter 6)? When do eukaryotes appear in the fossil record?

Eukaryotic organisms are those with a well-defined nuclear wall, definite chromosomes, and a capacity for sexual reproduction. By contrast, prokaryotic organisms possess cells with no definite nucleus

and lack membrane-bounded organelles. They are capable of only asexual reproduction and are typically smaller. The earliest appeared about 1.6 to 1.4 billion years ago.

8. What are metazoans? What is the earliest known occuresnce of abundant metazoans? With regard to their general appearance, what are the three major groups of Ediacaran metazoans?

Metazoans are multicellular animals.

The earliest known occurrence is in the Rawnsley Quartzite (late Proterozoic) of Australia.

3 Groups: The fauna, called the Ediacaran Fauna, is comprised of the impressions of worm-like; discoidal, jellyfish-like; and frond-shaped animal groups.

11. When did continental glaciation occur during the Proterozoic? What is the evidence that such glaciation occurred? Why is it unlikely that continental glaciers would have formed during the Archean?

In the region north of Lake Huron, there exist conglomerates and laminated mudstones assigned to the Gowganda Formation. The unsorted conglomerates and varied sands and shales are indicative of glacial conditions. The period of glaciation occurred sometime between 2.6 and 2.1 billion years ago. The higher thermal regimes of the Archean would have made sufficient ice accumulation to form glaciers improbable.

13. Stromalites were exceptionally widespread during the Proterozoic but became relatively sparse thereafter. What other organisms may have contributed to the post – Proterozoic decline of stromatolites?

The stromatolitic microbial organisms evidently provided food for newly evolved small shelly fossils and other primitive invertebrates. Extensive overgrazing decimated the Stromatolites. The stromatolites can only survive in environments unsuitable for most grazing invertibrates.

Charles Darwin – Natural SelectionNicolaus Steno – Superposition of StrataGeorges Cuvies – Extinction and CatastrophismWilliam Smith – Faunal SuccessionUniformitarianism – James Hutton

Longest Half Life: Rubidium 87:Strontium 87

Geologic time scale shortest duration – CenozoicHalf Life – The amount of time it takes for half of the original parent atoms to decay to more stable daughter products.

Permain Not defined in Great BritainAtomic Number – Number of Protons in the NucleusPennsylvanian – Not named by Robert Impey MurchisonAlpha Decay – Nucleus fires of a positively charged particle comprised of two protons and two neutrons.

Radiometric Dating – Absolute/Actual age of a geological feature

Igneous – Intrusive and Extrusive rocks. Determined by size of crystals. Metamorphism – adjacent to a mass of molten magma contact metamorphism.

Silicates == 92% of Earth’s crust.

Slate – Least intense grade of metamorphism.

Silicon and Oxygen – Most abundant elements of Earth’s crust.

Feldspar –Most abundant mineral in the Earth’s crust.

Metamorphic Rocks – Foliated or Non - foliated.

Quartzite and marble – Non - foliated.

Texture – Size and shape of sedimentary particles.

Rock that forms deep underground – Sialic Composition. Granite.

Clastic sedimentary rocks. Particles larger than 2mm Sandstone, siltstone.

Marine sedimentary rock – Limestone.

Sedimentary rocks – Lithification. Compaction + cementation.

Igneous – Cooling of molten materials.

Feldspar sedimentary clay during weathering process. Most abundant sedimentary rock on Earth is Shale.

Muscovite – Hardness 2-3, Perfect Cleavage, Specific gravity of 2.8 – 3.

Metamorphism adjacent to a mass of molten magma Contact metamorphism.

92% of Earth’s crust Silicates.

Slate least intense grade of metamorphism.

Silicon + Oxygen Most abundant elements in rocks in Earth’s crust.

Feldspar Most abundant mineral in the Earth’s crust.

Nonfoliated Quartzite and marble.

Middle Oligocene

Modern Sea Level – Below the Phanerozoic average.

Arkose – Sand – Grains of Feldspar, Quartz, Mica, and Chert

Arkose Compositionally immature but texturally mature.

Sedimentary particles comprising the rock were eroded from – A source area where granite was exposed at the surface.

1,900 years – Length of time to completely flood the portion of Florida shown on the map.

Limestone – forms in the warm shallow seas that cover the Everglades.

Disconformity –

Marine Transgression – Sea level rises relative to the land and the shoreline moves toward higher ground. Results in flooding.

Beach – Transitional depositional environment.

Alluvial fan – Red sandstones interbed with thick layers of poorly sorted but partially rounded conglomerate.

Desert --- Best sorted sediments.

Turbidity Currents – Sediment grains and occurs under the sea.

It is possible to correlate the Red Eagle Limestone with other sections.

Intertidal Zone – Littoral. (Technical Term).

Reorientation of the shell – Does the least violence to the potential fossil.

Study of processes affecting a fossil organism from the time of its death until final burial Biostratinomy.

Diploids Cells paired with homologus chromosomes (Full complement of genetic information).

Darwin + Lamarck All modern species are descended from ancestral species via evolution.

, ,

Vestigal structures. Wisdom Teeth in Humans Appendix in humans Pelvis in whales

Theory of punctuated equilibrium --Eldredge and Gould.

Gene pool -- Sum of all gene combinations.

Species-- Group of organisms that look alike and are able to interbreed. Basic unit of biological classification.

Not known to Darwin = During reproduction, genes are passed from parent to offspring.

All animals posses Eukaryotic Cells.

Punctuated Equilibrium – Evolutionary theory favors rapid origination of species.

Single – Celled, Prokaryotic Bacteria are Monera.

Linneaus – System of binomial nomenclature for naming organisms.

Convergent evolution – Two or more unrelated lineages acquire similar morphological characteristics through time.

Mitosis – Asexual organisms and somatic (body) cells of sexual organisms divide

Genus – Humans are formally classified as Homo Sapiens. Homo Genus name.

Driving mechanism of evolutionary change inherent needs or wants of evolving organism.

Modern Genetics Process of evolution. Fossil record illustrates the patterns of change through time.

Quinine – Does not form cross members in DNA molecules.

Cladistic Phylogeny –

Stratophenetic Phylogeny – A method for determining the evolutionary relationships among organisms that exist only as fossils.

Group of closely related classes is a taxonomic phylum.

Core Has a Density of 10.7

Mohorovicic Discontinuity Transition from crust to mantle.

Iron and nickel is the most likely composition.

False Shadow zone for P waves is larger than that of S waves.

Aleutian/Japanese Islands Ocean/Ocean Convergence.

Continental crust is granitic, Oceanic crust is Balsaltic.

Wegener Argued that all of the major continents were assembled into a single supercontinent at the end of the Paleozoic era.

False base of lithosphere coincidesd with the Mohorovicic discontinuity.

Hawaiian Chain Intraplate volcanism associated with a hot spot.

Red Sea and the Gulf of Aden Example of divergent plate margins.

Thermoremanent Magnetism forms in igneous rocks cooling below the Curie Point.

Pacific plate does not contain an appreciable amount of continental crust.

Cocos and Carribeam are most similar in size.

Juan de Fuca – Smallest plate on the map.

Source of Magams fueling Mt. St. Helens Partial melting of the subducting Juan de Fuca Plate.

New Granitic Crust is currently being generated under Western Washington

True Polarity reversals appear to have been less frequent in the early half of the Eocene than in the later half of the Eocene.

Plastic, partially molten layer upon which the lithospheric plates move is the asthenosphere.

New Oceanic crust is formed at Midocean ridges.

3 Types of plate boundaries – Convergent, Divergent, & Transform fault.

Midway Island was centered over the spot 18 million years ago.

Dickinsonia Worms Yilgarn – Pilbara Shield complex Australia.

50 Percent of North America existed 2.5 billion years ago.

Venus is a Jovian planet.

Hot accretion theory suggests Earth’s internal layering originated during accretion.

Venus Density most similar to that of Earth.

Oldest fossil metazoans belong to is the Ediacaran fauna Ediacara Hills of Southcentral Australia in the 1940’s.

Elrathia are not part of this late Proterozoic faunal assemblage.

Oldest known calcium carbonate, shell – bearing fossils belong to

--Palmatolepis-- Cloudina

90% of Earth’s banded iron formations were formed during the late Archean

Hadean

Sun is powered by the fusion of hydrogen atoms to form helium.

Prokaryotes are simpler, & larger than Eukaryotes.

Early atmosphere was produced by volcanic outgassing. Primitive atmosphere did not contain water vapor (component of volcanic outgassing).

Precambrian comprises roughly 86% of Earth’s history.

Geologically stable part of a continent where Precambrian basement rocks are covered by a thin blanket of younger sedimentary rocks is called the stable platform.

Proliferation of Stromatolites in widespread, shallow oceans that existed during the Precambrian would have resulted in an increase of ______ in Earth’s atmosphere.

In Precambrian banded iron formations the red layers have a composition of Fe2O3.

Oldest rocks currently known on Earth are 3.96 billion years old and are classified as tonalite gneiss.

Stanley miller speculated that life originated on this planet sometime during the Precambrain. He set up a glass apparatus containing gases common in the Precambrian atmosphere and subjected tjem to electrical sparks.

At the end Miller found proteins and DNA in his apparatus.