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Copy of Copy of Copy of Weathering & Erosion By Brooke And Lillie

Published on Dec 01, 2015

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PRESENTATION OUTLINE

1.

WEATHERING

  • The process of wearing away and changing.
  • Rocks are broken down in smaller pieces by the effects of weather.
  • Earth's surface constantly changes due to weathering process.
  • This process can take millions of years to happen or happen relatively quickly.
2.

MECHANICAL WEATHERING

  • Weathering from external services: freezing and thawing.
  • Takes place when rocks are broken down without any changes in the chemical nature of rocks.
  • Rocks torn apart by physical force.
3.

CHEMICAL WEATHERING

  • Weathering when a chemical (like acid rain) breaks down rocks.
  • Break down bonds holding rocks together causing them to fall apart forming smaller pieces.
  • Common in locations with lots of water.
4.

DEPOSITION

  • Laying down of sediment carried by wind ,water , or ice.
  • Happens every time erosion happens.
  • The opposite effect of erosions.
  • Deposition in water always causes a sorting of particles (size, density, or shape) - for example the biggest on the bottom and smallest on top.
5.

EROSION

  • Process by which soil and rock particles are worn away and moved elsewhere.
  • Removal and transport of sediment.
  • Agents of erosion: Gravity, running water,moving ice , wind, wave action.
  • Transport is the cycle processes of moving sediment.
6.

DEFLATION

  • Removal of loose , fine grained particles by wind.
  • Lowers the land surface by removal of the small particles leaving the coarser grained behind.
Photo by Konabish ~ Greg Bishop
7.

SANDSTORM OR DUSTSTORM

  • Strong winds blow loose sand and dirt from a dry surface
  • Caused by low vegetation and disturbance of soil
  • Can blind drivers, knock out electricity and ground air flights
  • Sandstorm typically used in context of a desert storms. Dust storm is typically used when fine particles are blown long distances.
8.

WINDBREAK

  • Attempt to control erosion.
  • For example a field windbreak is a planting of trees and shrubs in a line to reduce wind speed in open spaces.
  • Scientists study wind tunnels to help design windbreak.
  • Sometimes called 'wind fences '.
Photo by Universal Pops (David)--Badly Needs Bandwidth
9.

ABRASION

  • Wearing down of surfaces by grinding action of particles in the wind.
  • Surface shaped by wind blown objects ( like sandblasting).
10.

LOESS

  • Wind deposits of finer sediments.
  • Win blown , silt , and clay deposited layer on layer over a large area.
  • Make very fertile soils in many regions of the world.
11.

DUNES

  • For a sand dune to form there must be a lot of sand and steady winds.
  • Located in deserts or seashores.
  • Beach dunes are usually made of Quartz.
12.

SOIL EROSION

  • Natural processes where soil is removed.
  • Agents of soil erosion are water and wind.
  • Big problem in US in 1930s dust bowl- winds removed the soil.
  • Half the topsoil on the planet has been lost in the last 150 years.
  • Leads to increased pollution and sediments in streams and rivers.
13.

OVERGRAZING

  • Happens when vegetation in an area is exposed to intensive grazing for an extended period of time; for example livestock (too many animals in an area or not properly controlled grazing).
  • Plants become weaker and have shorter roots which means they might die during the winter .
  • Overgrazing increases soil erosion.
14.

FOREST HARVESTING

  • Soil erosion in undisturbed forests is very low because of all the ground cover (" forest litter").
  • Can be called " clear cutting" and most or all the trees in an area are cut down.
  • It destroys natural habitats and contributes to climate change and increases soil erosion.
15.

AGRICULTURAL CULTIVATION

  • Cultivation of animals and plants for food, fuel, medicine and other products for humans .
  • Man began growing crops 10,000 years ago.
  • Organic farming is gaining in popularity since beginning in the 1940s.
16.

Mass Movement

  • Movement of massive bodies of soil, bed rock, rocks
  • earth materials moving down slope under the influence of gravity
  • Caused by: Volcanic activity, Earthquake shocks Human modification, Vibrations from machinery, and Mudslides
17.

Slump

  • moves materials as a large block along a curved surface; movement is slowly down a hillside
  • A slipping of a rock happens when too much weight is added to an unstable slope or the slope is undercut
18.

Creep

  • slowest type of mass movement- entire side of a hill or mountain moves down
  • so slow special equipment is needed just to measure the movement (less than one inch per year)
19.

Mudflow

  • Flow of water that contains large amounts of suspended particles and silt.
  • Hillsides with soils rich in clay and not much vegetation experience mudflows in times of high precipitation
  • Higher density and Viscosity than a stream flow
20.

Rockfall

  • rocks cascade down a slope but not a large volume
  • usually occur at a very steep slope like a cliff face
  • rocks can be loosened by earthquake, rain, expanding ice, and plant roots
21.

Rockslide

  • sudden rapid slide of bedrock
  • common in canyons (example in the Salmon River Canyon where more than 5,000 feet exists between the top and bottom)
22.

GLACIER

  • fallen snow that over many years compresses in a large thick mass of ice.
  • Have the ability to move because of their mass flow like a very slow river.
  • Some are hundreds of kilometers long.
Photo by christine zenino
23.

PLUCKING

  • Occurs when rocks become frozen to the base or sides of a glacier.
  • As the glacier moves these rocks are removed from the ground and leave behind a hole.
24.

MORAINE

  • Rock debris carried or deposited by a glacier.
  • Ground moraine is a blanket of debris under a glacier.
  • Terminal moraine is a ridge like pile of debris pushed forward.
  • Other types are lateral, medial, and recessional.
25.

TILL

  • Unsorted sediment deposited by a glacier.
  • Sometimes called " Boulder clay".
  • Ranges from clay sized to Boulder sized and can weigh thousands of tons.
26.

ESKER

  • Long narrow ridge of sand and gravel deposited by a meltwater stream marking the former location of a glacial tunnel.
  • Channel deposited marketing the routes of rivers and streams that flowed on , in and beneath The glaciers.
  • Comes from an Irish Gaelic word "eiscer " meaning "ridge".
27.

OUTWASH

  • Plain formed by deposit of sand and gravel carried by running water from the melting glaciers.
  • Also called 'sandur' .
  • May contain 'kettle lakes' where blocks of ice have melted leaving a depression.
28.

CONTOUR FARMING

  • Growing crops across or perpendicular to a slope rather than up and down the slope.
  • The rows across the slope are designed to be as level as possible.
29.

NO-TILL FARMING

  • Growing crops without disturbing the soil with digging, stirring and overturning.
  • Increases the amount of water that gets into the soil and increased organic matter retention and nutrients.
30.

TERRACING

  • Make or form sloping land into a level flat areas resembling a series of steps.
  • Found on mountains.
31.

METHODS USED AT CONSTRUCTION SITES

  • Must submit " Soil and Erosion and Sediment Control plans" to local conservation districts.
  • Stabilized construction access ( crushed stone ).
  • Review permanent vegetative measures.
  • Wire mesh in front of storm water inlets and storm water basins.
  • Put in temporary measures while constructing to limit disturbance ( straw, mulch, silt fencing, crushed stone).

Lillian Daniel