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Surface Processes and Landscapes Weathering

Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

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Page 1: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Surface Processes and Landscapes

Weathering

Page 2: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Weathering and Weathering and ErosionErosion

WeatheringWeathering is the chemical and physical breakdown of rocks into smaller fragments.

ErosionErosion is the movement of weathered material from one place to another.

Page 3: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Weathering TypesWeathering Types

The two general types of weathering are physicalphysical and chemicalchemical.

Physical weatheringPhysical weathering occurs when rock is cracked, split, or broken into sediments with no changeno change in in the rock compositionthe rock composition.

Chemical weatheringChemical weathering occurs when rock is broken down by chemical action resulting in a changechange in the in the compositioncomposition of the rock.

Page 4: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Types of Physical Types of Physical WeatheringWeathering

• Frost actionFrost action – caused by alternate freezing and thawing of water.

• AbrasionAbrasion – caused as rocks rub or bounce against each other.

• ExfoliationExfoliation is the peeling away of large sheets of loosened surface material.

• RootsRoots from large trees and shrubs as well as roots from lichens and mosses will split rocks as they grow.

Page 5: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller
Page 6: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Types of Chemical Types of Chemical WeatheringWeathering

OxidationOxidation occurs when oxygen combines chemically with minerals. Ex. is rust.

HydrationHydration occurs when water combines chemically with minerals. Ex. is when feldspar or hornblende combine with water and form clay.

CarbonationCarbonation occurs when carbon dioxide combines with minerals. Example is carbonic acid which dissolves limestone creating caves, sink holes, stalactites and stalagmites.

Organic DecayOrganic Decay occurs when acids from decaying organic matter dissolve rock minerals.

Page 7: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller
Page 8: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

SoilsSoils

SoilSoil is one of the major products of weathering.

SoilSoil is the part of the weathered regolith in which rooted plants will grow.

SoilSoil is composed of rock minerals and organic matter and consists of all 3 states of matter.

Page 9: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Soil FormationSoil Formation

Soil types depend upon their place of origin.

Soil formed by the weathering of the bedrock found beneath it is called residual soilresidual soil.

Soil formed from rock that was moved to its present location is called transported soiltransported soil.

Page 10: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Soil ProfileSoil ProfileAs soils mature they grow richer and

develop a series of layers called a profileprofile.

TopsoilTopsoil is the uppermost layer containing the most organic matter and the most weathered rocks.

SubsoilSubsoil is below the topsoil and is rich in clay-sized particles but contains little organic matter.

Below the subsoil is partly weathered bedrock on top of unweathered bedrock.

Page 11: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller
Page 12: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller
Page 13: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller
Page 14: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Soil SolutionSoil Solution

• A soil solution is the end product of weathering; a solution of ground water containing ions of potassium, nitrate, phosphate, calcium and iron that the water picked up as it seeps through soil.

Page 15: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Soil ConservationSoil Conservation• Due to the large demands upon

earth’s farmable land, use of soil must be carefully planned and managed.

• DepletionDepletion occurs when too many nutrients are removed form the soil for crops to grow.

• Crop rotation, contour plowing, strip Crop rotation, contour plowing, strip cropping, terracing, and wind breakscropping, terracing, and wind breaks are all farming practices designed to preserve soil.

Page 16: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

ErosionErosion

• Erosion is the transportation of loose sediments or rocks produced by weathering.

• The major mechanisms of erosion are:– Gravity– Running water– Glaciers– Wind and– Waves

Page 17: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Types of SedimentTypes of Sediment

• Transported sedimentTransported sediment is rock material that has been moved to another location.– Transported materials will become

abradedabraded as they grind and bump against other rock material. These materials begin to appear rounded as they are abraded.

• Residual sedimentResidual sediment is rock material that has weathered and remained in its place or origin.

Page 18: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Running Water and Running Water and ErosionErosion

Any running water makes a streamstream.Gradient, discharge, and channel shape

influence a stream’s velocity and the erosion and deposition of sediments.

Stream featuresStream features include: v-shaped valleys, deltas, flood plains and meanders.

A watershedwatershed area is the area drained by a stream and it’s tributaries.

Page 19: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Stream VelocityStream Velocity

• Carrying powerCarrying power is the ability of a stream to move particles of different sizes and this depends upon velocityvelocity.

• Velocity (speed)Velocity (speed) of a stream depends upon stream dischargedischarge and gradientgradient.– DischargeDischarge is the volumevolume of water.– GradientGradient is the steepnesssteepness of the slope.

Page 20: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

StreamStream VelocityVelocity andand GradientGradient

Page 21: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Velocity and Channel Shape

Page 22: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Velocity and Sediment Size

Greater stream velocity will carry larger sediments.

Stream loadStream load is the material that a stream carries.

Page 23: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Stream Load• Load is the material

that a stream carries.

• 3 ways to carry load:– Solution = disssolved– Suspension = floating– Saltation = bouncing

Page 24: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Wind and Ice Erosion

• Wind: greater velocity carries larger particles.

• Ice: greater volume carries larger particles.

Page 25: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Glacial Erosion

Page 26: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Effects of Erosional Agents: Valley Shapes

River erosion creates “V-Shaped” valleys.

Glacial erosion creates “U-Shaped” valleys.

Page 27: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

DepositionDeposition• Deposition Deposition is the final step in an is the final step in an

erosional-depositionalerosional-depositional system. system.– Factors affecting depositiondeposition are:

• Particle size, shape, density• Velocity• gradient

– Rock particles are eventually depositeddeposited somewhere:• by sedimentation = droppingdropping of particles• by precipitation = dissolved minerals “fall” “fall”

out out of solution.

Page 28: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller
Page 29: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Horizontal Sorting• As a stream or

river enters a larger body of water, the velocity decreases as distance from the mouth increases.– As a result the

biggest particles fall out first and the smallest travel the farthest.

Page 30: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Crossbedding

Page 31: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Glacial Deposition• Glacial deposits are unsorted (all mixed with no

layering or bedding) and deposits are mostly 2 types:– Till is unsorted rock deposited directly by the glacier;– Outwash is rock material deposited by the meltwater of a

glacier.• Outwash can show horizontal sorting.

– Erratics are large boulders deposited by glaciers.

Page 32: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Erosional – Depositional System

• An erosional-depositional system combines the erosion process, transportation agents, and deposition.

• A river is a combination of continual erosion and deposition.

Page 33: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller
Page 34: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

River TermsRiver Terms

• SourceSource = beginning w/most potential energy.

• MouthMouth = end, where it flows downstream to.

• MeanderMeander = curve or bend.• Flood plainFlood plain = land between

the stream and steep walls of the valley.

• DeltaDelta = deposit of sediment at the mouth of a river.

• Alluvial fan Alluvial fan = deposit of sediment formed where river slows as it flows out of mountains.

Page 35: Surface Processes and Landscapes Weathering. Weathering and Erosion Weathering Weathering is the chemical and physical breakdown of rocks into smaller

Flood Plain (above) and stream history, oxbow, (left)