Chapter 14: Weathering & Erosion

Section 4: Erosion

Erosion – transporting weathered material, agents – gravity, wind, glacier, & water Soil erosion major concern Soil erodes faster than its made Land use & climate affect S.E. Affects crops

Gullying – soil washed away forms gullies, rapid erosion Sheet erosion – topsoil washed away, leaves subsoil

Soil Conservation Human Effects Solutions? Farming, grazing, construction increase E. rates Solutions? Contour farming – plowed according to shape of land Strip-cropping – alternating pattern of crops Terracing – planted in curves on slopes Crop rotation – alternate crops grown Wind Breaks – blocks the wind Terracing Contour farming Strip cropping

Gravity & Erosion Rockfalls – from steep cliff Mass movement – lg. amts. of soil flows downhill Rockfalls & landslides – Rockfalls – from steep cliff Landslides – lg. mass of rock & soil quickly moves downhill

Gravity & Erosion Slump Mudflows – mountainous regions w/heavy rainfall or w/ volcanic eruptions Slumps – lg. mass of soil & rock that moves downhill in 1 piece

Gravity & Erosion Solifluction – arctic & mountainous areas, saturated soil moves over frozen soil Creep – slow downhill movement Rock fragments pile up @ base of slope - Talus

Erosion & Landforms Mountains Mts. being uplifted have sharp peaks & narrow valleys Over time they wear down forming PENEPLAINS – slow rolling hills Plateaus lg. flat raised landform Dry conditions Plateaus  mesas  buttes Plateau, vs Mesa vs Butte: If they all have flat tops and steep sides, why aren't they all referred to as buttes, or mesas, or plateaus? In laymen's terms, a butte is a small flat-topped or pointed hill or mountain. A mesa is a medium size flat-topped hill or mountain. And a plateau is a really big flat-topped hill or mountain.

Glaciers & Rivers U-shaped V-shaped

End of Section 4 review 1. What are 4 agents of erosion? 1. wind, water, glaciers, & gravity 1. What are 4 agents of erosion? 2. Summarize two processes of soil erosion. 3. Identify 4 farming methods that result in soil conservation 4. What are 2 ways gravity contributes to erosion? 5. Compare rapid mass movements with slow mass movements 6. Describe the erosion of 3 major land forms CONTINUED ON NEXT SLIDE 2. Gullying = plowed furrows up & down a slope, rain rushes though widening the furrow; Sheet erosion – water or wind goes over soil & removes the top layer of soil in entire sheets 3. Contour farming, strip cropping, terracing & crop rotation 4. Moves water down slopes & causes mass movement of rocks and soil 5. Rapid = rockfalls, landslides, mudflows & slumping can be catastrophic; Slow = creep & solifluction – not as catastrophic but moves greater amount of material over time 6. Mountains are eroded from rugged peaks into rounded slopes; plateaus are eroded into buttes and mesas

Section 4 review continued 7. Describe an experiment that could help you determine whether a nearby hill is undergoing creep. 8. Suppose that you wanted to grow grapevines on a hillside in Italy. What farming methods would you use? Why? 9. Describe 2 ways that a small butte would change if it was in a wet climate rather than dry climate. 10. A hillside community has asked you to help brain storm ways to prevent future mudflows. What are 3 methods you might use? 7. Place a stick in the ground on a slope and monitor its position over time (see if it changed/moved) 8. Contour planting with strip cropping between the rows of vines or terracing to reduce hillside erosion 9. He butte would probably have shallower slopes and more rounded tops 10. Increase ground cover to hold soil in place with the roots of the plants; build retaining walls to hold soil back during rain storms, do not allow building and deforestation