Chapter 8Earth Systems and Resources

The Earth’s resources were determined when the planet

formed.

•Earth was formed roughyly 4.6 billion years ago.

•Molten material slowly cooled, separated into layers based on mass.

The Earth’s resources were determined when the planet

formed.

Core- the innermost zone of the planet made of nickel and iron.

Mantle- above the core containing magma

Crust- the outermost layer of the planet.

The Earth’s Layers

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Asthenosphere- the outer part of the mantle, composed of semi-molten rock.

Lithosphere- the brittle outermost layer of the planet that is approximately 100 km thick. (smaller plates)

The Earth’s Layers

Checkpoint…

How did Earth form? What is the composition of each of Earth’s

layers? What is the practical significance today of

the way Earth’s resources were distributed when the planted formed and cooled?

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Earth is dynamic and constantly changing…

Earth’s geologic cycle consists of 3 major prcesses:

Tectonic cycle Rock cycle Soil formation

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The Earth is very hot at the center. This heat causes plumes of hot magma to well upward

from the mantle. (convection) High temp. of mantle and outer core – due to

radioactive decay. Hotspots- places where molten material from the

mantle reach the lithosphere.

Convection and Hot Spots

Plate tectonics- the theory that states that Earth’s lithosphere is divided into plates, most of which are in constant motion.

Alfred Wegener – German

meteorologist – 1912. Pangea Tectonic cycle – sum of the

Processes that build up and

Break down the lithosphere. Continental vs Oceanic plates

Theory of Plate Tectonics

Theory of Plate Tectonics

Tectonic Plates

Sea floor spreading – slow drifting of plates, rising magma forming new crust on seafloor.

Subduction – heavier oceanic plate sliding below lighter continental plate

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Consequences of Plate Movement

Volcanoes- as a plate moves over a hot spot, rising magma forms a volcano.

Consequences of Plate Movement

Divergent plate boundaries- when plates move apart from one another. (sea-floor spreading)

OCEAN ----------------- OCEAN

Convergent plate boundaries- when plates move toward one another and collide. (subduction)

OCEAN---OCEAN OCEAN--CONTINENTAL

Transform fault boundaries- then plates move sideways past each other.

CONTINENTCONTINENT

Types of Plate Contact

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Faults- a fracture in rock across which there is movement.

Earthquakes- occur when the rocks of the lithosphere rupture unexpectedly along a fault.

(transform fault boundary )

Faults and Earthquakes

Fault zone- large expanses of rock where movement has occurred.

Fault – fracture in rock where there is movement.

Epicenter- the exact point on the surface of Earth directly above the location where the rock ruptures.

Seismic activity occurs at fault zones or areas where earthquakes are common.

Faults and Earthquakes

Environmental and Human Toll of Earthquakes and

Volcanoes Richter scale- a measure of the largest

ground movement that occurs during an earthquake. The scale increases by a factor of 10, so an earthquake of 7 is 10 times greater than an earthquake of 6. (logarithmic)

Bill nye – Earthquakes! http://www.bing.com/videos/search?

q=bill+nye%2c+earthquakes&view=detail&mid=9024D15A0C1A5F56168C9024D15A0C1A5F56168C&first=0&FORM=NVPFVR

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Check point…

What is the theory of plate tectonics?

What are some environmental consequences of the tectonic cycle?

How do earthquakes and volcanoes occur?

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Rock cycle- the constant formation and destruction of rock.

The Rock Cycle

The Rock Cycle(Constant formation and destruction of

rock)

Rocks are the substance of the lithosphere

Rocks are composed of minerals Minerals – solid chemical substances with

uniform (often crystalline) structures that form under specific pressure and temp.

Can be made of compounds or one single element.

Igneous rocks- rocks that form directly from magma.

Intrusive igneous- form from within Earth as magma cools.

Extrusive igneous- from when magma cools above Earth. (ex. A volcano that ejects magma out will form this)

Sedimentary rocks- form when sediment such as mud, sands, or gravels are compressed by overlying sediments.

Metamorphic rocks- form when sedimentary, igneous or other metamorphic rocks are subjected to high temperatures and pressures.

The Rock Cycle

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Weathering- when rocks are exposed to air, water, certain chemicals or biological agents that degrade the rock.

Physical weathering- the mechanical breakdown of rocks and minerals.

Weathering and Erosion

Chemical weathering- the breakdown of rocks and minerals by chemical reactions.Acid rain

Weathering and Erosion

Erosion- the physical removal of rock fragments from a landscape or ecosystem. Wind, water, ice transport and living organisms can erode materials.

Deposition- the accumulation or depositing of eroded material such as sediment, rock fragments or soil.

Erosion

Check point…

What is the rock cycle?

What re the 3 basic rock pes, and how is each formed?

What is the difference between weathering and erosion? Why are both important?

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Mix of geologic and organic components.

Soil is important because it Is a medium for plant growth Serves as a filter for water A habitat for living organisms Serves as a filter for pollutants

Soil

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Factors that determine the formation of soil: Parent material- what the soil is made from influences soil formation

Climate- what type of climate influences soil formation

Topography- the surface and slope can influence soil formation

Organisms- plants and animals can have an effect on soil formation

Time- the amount of time a soil has spent developing can determine soil properties.

The Formation of Soil

Parent Material- the rock material from which soil is derived.

The Formation of Soil

As soils form, they develop characteristics layers.

Soil Horizons

O horizon- (organic layer) composed of the leaves, needles, twigs and animal bodies on the surface.

A horizon- (topsoil) the zone of organic material and minerals mixed together.

B horizon- (subsoil) composed primarily of mineral material with very little organic matter

C horizon- (parent material) the least weathered horizon and is similar to the parent material.

Soil Horizons

Texture- the percentage of sand, silt and clay the soil contains.

Physical Properties of Soil

Porosity- how quickly the soil drains (which depends on its texture)

Physical Properties of Soil

Chemical Properties of Chemical Properties of SoilSoil

Cation exchange capacity (CEC)- the ability of a soil to adsorb and release cations, positively charged mineral ions.

Soil bases- calcium, magnesium, potassium and sodium

Soil Acids- aluminum and hydrogen

Base saturation- the proportion of soil bases (Calcium, magnesium, potassium and sodium) to soil acids

Chemical properties of soil…

With the exception of sodium, all bases are essential for plant growth

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Biological Properties Biological Properties of Soilof Soil

Many organisms are found in the soil including fungi, bacteria, protozoans, rodents and earthworms.

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Check point…

How do soils form?

What are the roles of soils in ecosystems?

How do a soil’s physical and chemical properties influence its role as a medium for plant growth?

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Elemental Composition of the Earth’s Crust

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Reserves Reserves- the known quantity of a

resource that can be economically recovered.

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Types of Mining Surface mining- removing minerals that

are close to Earth’s surface. Strip mining- removing strips of soil and rock to expose ore.

Open pit mining- the creation of a large pit or hole in the ground that is visible from the surface.

Mountain top removal- removing the entire top of a mountain with explosives.

Placer mining- looking for metals and stones in river sediments. 47

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Types of Mining Subsurface mining- mining for resources

that are 100 m below Earth’s surface.

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SURFACE MINING

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Strip mining

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Open pit mining

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Mountain top removal

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Placer mining

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SUBSURFACE MINING

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Reclamation

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Checkpoint…

Why are economiocally valuable mineral resources distributed unevenly on the planet?

Describe the various types of surface mining.

What are the consequences of surface mining versus subsurface mining, and how has mining legislation tried to reduce those impacts? 58

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