Erosion, & Types of Erosion, & Types of WeatheringWeathering

Chapter 10Chapter 10

ErosionErosion

A processA process where water, where water, wind, or wind, or gravity gravity transports transports soil soil (sediment) (sediment) from its from its sourcesource

The process The process by which rocks by which rocks are broken are broken down into down into smaller piecessmaller pieces

There are 2 There are 2 main types, main types, chemical & chemical & PhysicalPhysical

Weathering

Mechanical WeatheringMechanical Weathering

The break down of The break down of rock into smaller rock into smaller pieces due to pieces due to physical meansphysical means– Frost wedgingFrost wedging (water (water

freezing in rock freezing in rock cracks) cracks)

– AbrasionAbrasion (other (other rocks or sediment rocks or sediment rubbing against rubbing against rock.)rock.)

Chemical WeatheringChemical Weathering

Rocks break Rocks break as a result of as a result of a chemical a chemical changechange– Acid rainAcid rain– Chemical Chemical

decompositiondecomposition– Gases in the air Gases in the air

(oxidation)(oxidation)

DepositionDeposition Is the process Is the process

where where material lays material lays to restto rest

Sediment is Sediment is deposited in deposited in bodies of water bodies of water and on landand on land

Chapter 6 Chapter 6

The Rock RecordThe Rock Record

Sedimentary Rock LayersSedimentary Rock Layers This is a normal record of rock. Layers are This is a normal record of rock. Layers are

undisturbed. The Geologic Column is a undisturbed. The Geologic Column is a model of what rock layers should look like.model of what rock layers should look like.

UniformitarianismUniformitarianism

A principle or rule that states A principle or rule that states that events that happened in the that events that happened in the past can be explained by current past can be explained by current earth (geologic) processesearth (geologic) processes

Earth Processes like erosion, Earth Processes like erosion, weathering, and deposition weathering, and deposition remain uniformed and do not remain uniformed and do not change.change.

CatastrophismCatastrophism

A principle that states that A principle that states that geologic changes happen geologic changes happen suddenly. (suddenly. (natural disastersnatural disasters))

They believed the Earth was only They believed the Earth was only a few thousand years old.a few thousand years old.

Catastrophic events formed the Catastrophic events formed the Earth, created volcanoes, Earth, created volcanoes, mountains, oceans, etc.mountains, oceans, etc.

Relative DatingRelative Dating

Determines which comes Determines which comes first. Determining if rock first. Determining if rock layers are older or layers are older or younger younger

Compare them to Compare them to undisturbed rock around undisturbed rock around the worldthe world

Principle of SuperpositionPrinciple of Superposition

A principle or rule A principle or rule that states that that states that younger rocks lie younger rocks lie above older rocks in above older rocks in un-disturbed un-disturbed sequencessequences

As you move from As you move from top of rock layers to top of rock layers to the bottom the rock the bottom the rock layers get olderlayers get older

SUPERPOSITIONSUPERPOSITION

UpliftUplift

movement movement within the within the Earth that Earth that moves moves rocks to rocks to the surfacethe surface

UnconformitiesUnconformities

Is a disturbance in the layer of a rock. Is a disturbance in the layer of a rock. Represents thousands, to millions of years Represents thousands, to millions of years

in missing time in the layers of a rockin missing time in the layers of a rock Can be created through: Can be created through:

– Erosion and weathering (p159, figure 4)Erosion and weathering (p159, figure 4)– Faulting- (earthquakes)Faulting- (earthquakes)– Folding (anticlines, synclines, and monoclines)Folding (anticlines, synclines, and monoclines)– TiltingTilting– intrusionintrusion

Rock Rock IntrusionIntrusion A layer of molten A layer of molten

rock (hardened rock (hardened magma) from the magma) from the Earth’s interior Earth’s interior that squeezes into that squeezes into existing rock and existing rock and then cools.then cools.

Melts surrounding Melts surrounding layerslayers

Interrupts the rock Interrupts the rock time scale.time scale.

Types of UnconformitiesTypes of Unconformities

DisconformityDisconformity – part of a parallel rock – part of a parallel rock layer is missing. (layer is missing. (Layers may be Layers may be eroded away and deposited elsewhere)eroded away and deposited elsewhere)

NonconformityNonconformity- horizontal - horizontal sedimentary rock layers lay on the sedimentary rock layers lay on the eroded surface of intrusive igneous eroded surface of intrusive igneous rocks or metamorphic rocks rocks or metamorphic rocks

Angular unconformity-Angular unconformity- rocks are tilted rocks are tilted or folded due to earthquakes or uplift or folded due to earthquakes or uplift (p 160)(p 160)

TermsTermsErosionErosionWeatheringWeatheringUpliftUpliftDeforestationDeforestationMechanical Mechanical

weatheringweatheringChemical Chemical

weatheringweathering

Relative datingRelative dating UniformitarianisUniformitarianis

mm SuperpositionSuperposition IntrusionIntrusion CatastrophismCatastrophism Un-conformityUn-conformity Strip MiningStrip Mining Frost WedgingFrost Wedging AbrasionAbrasion