WEATHERING AND EROSION

Processes that change the surface of the Earth n Mechanical n Mechanical or Physical Weathering n Chemical n Chemical Weathering n Erosion n Tectonic n Tectonic Activity (volcanoes, earthquakes.etc.)

COMMON NATURAL FORCES OF CHANGE n Wind n Water n Plants n Animals n Animals (including humans)

MECHANICAL WEATHERING n Rocks n Rocks and other materials break apart via physical means - similar to physical changes in chemistry n Chemical n Chemical makeup stays the same n wind, n wind, burrowing animals, plants, ice

CHEMICAL WEATHERING n Chemical n Chemical reactions on the surface breakdown or dissolve the minerals in the rock or other material - similar to chemical changes in chemistry n The n The chemical makeup changes n acid n acid rain, oxidation (rusting), plant acids, lichen, carbonic acid (caverns)

EROSION n Process n Process by which weathered materials are carried away n water, n water, wind, ice, gravity, humans n water n water is the MOST significant force of erosion

RIVERS n Begin n Begin as rills >> gullies >> streams >> rivers n Deposit n Deposit sediment as they lose energy - slow down n Form n Form deltas when they reach seas, oceans, gulfs, lakes

Rivers cont. n Create n Create “V” shaped valleys n Colorado n Colorado River carved out the Grand Canyon over millions of years n As n As they age the meanders increase and oxbow lakes may appear

Rivers cont. n Important n Important to human activity n Develops n Develops rich fertile soils n Can n Can be very destructive n Provide n Provide recreation and challenges

MASS WASTING OR MOVEMENT n Gravity n Gravity is the force behind mass movement n Landslides, n Landslides, mudslides, slump, creep n Water, n Water, lack of vegetation, steep slopes can create conditions that are ripe for mass movement

WIND n Causes n Causes abrasion - sand and small particles polish and smooth jagged edges n Reshapes n Reshapes the landscape - sand dunes n Can n Can be very destructive - reach speeds over 100mph

GLACIERS n Create n Create “U” shaped valleys - Yosemite National Park n Sharp n Sharp mountain peaks called Horns, Glacier Lakes (Minnesota, Great lakes) n Move n Move HUGE masses n Studied n Studied to learn about current and past climate changes

DAMS Pros and Cons n Prevent n Prevent flooding n generate n generate energy n create n create lakes, reservoirs n Displace people n destroy habitat n interrupt fish migration n endanger wildlife n change flow of sediments and rivers

Human Activities n Land n Land Developing - housing, industry, farming n Mining n Mining of Resources n Damming n Damming of Rivers

Weathering and Erosion are processes that continue on a non stop basis.