Mass+movements

Mass Movements Movements of loose earth material down a slope A) **Gravity is an aid in weathering and erosion. Steep slopes weather to gentle slopes. Creep- Slow, Imperceptible down slope movement of the soil. Causes objects that are fixed in the soil to lean downhill. Water in the soil is what adds the weight Mudflow-The rapid movements of a water saturated mass of soil

Slump- Occurs when a section of land moved downhill as a whole because of a plane of weakness in the underlying soil. Landslide- sudden movement of a mass of bedrock or loose rock down the slope of a hill or mountain. (Avalanche -Snow, Ice, Rock and soil) **

Wind transports materials by causing their particles to move in different ways. Suspension- A method of transport by which strong winds cause small particles to stay airborne for long distances. Saltation-Causes a bouncing of motion for larger particles. Saltation accounrs for most sand transport by wind. Wind erosion is greatest in arid climates (low precipitation) With little vegetation (deserts and sea shores) Abrasion is a process of erosion found in wind, water, and ice. It occurs when particles suck as sand rub up against the surface of rocks or other materials Ventifacts-Are rocks shaped by windblown Sediments. Wind Deposition occurs in areas where wind velocity decreases. Dunes are piled of windblown sand that have a gentile side and a steep side. The gentler slope occurs when the side on which the wind is blowing (windward side). The steeper slope occurs on the side protected from the wind (leeward side). Loess- Thick deposits of fine lightweight particles (Silt, Clay) that are carried by the wind in great quantitates of long distances. They are some of the most fertile soils.
 * Wind Erosion

Louis Agassiz is known for the idea that glaciers once covered many parts of the world. Glaciers accumulations of ice large enough to survive summer melt- Forms from snow under pressure which turns to ice Snow line- The lowest level that permanent snows reach in summer Highest near the equator. Firn is granular ice material formed in snow fields from freshly fallen snow becoming compressed and re-crystallizing The lower layer become ice and begin flowing downward or outward because of overlaying pressure. Alpine Glaciers (valley glaciers) Occur in mountain regions above the snow line flow downhill and carve out U-shaped valleys A glacier that spreads over a wide geographic area. form in polar areas where the snow line is close to sea level and wide areas are above the snow line(responsible for much of the landscape in NY) 20,000 years ago, new york state was covered by a huge ice sheet that originates in canada.
 * Formation of a glacier
 * Continental Glaciers (ice sheets)



The overlying weight of snow and ice causes grains of ice partially melt and freeze. As the happens ice grains slip past each other and move downhill. Glaciers move more rapidly at the surface than at the base and faster at the center than at the sides. Friction with the valley walls slow. Crevasses are cracks across the width of the glaciers move over steep slopes. Ice Fronts is the end of a glacier, the ice front is stationary as long as the rate or movement and melting are equal A Glacier recedes when it melts faster then normal A Glacier Advances when the rate of movement is greater then the rate at which it melts. Pieces of rock are picked up as glaciers move and then are dragged along the bedrock and/or velley wall Fine sand acts as sandpaper and polish the bedrock Larger sediments leave long parallel Scratches called striations Striations show the direction of movement. The finger lakes of ny were formed as advancing ice deeply scoured out valleys Glacial trough are formed when a glacier carve out a valley forming a u-shaped valley Valley glaciers leave sharp mountain tops while continental glaciers leave rounded tops. Here are a few depositional features of Glaciers Moraine is a glacial deposit of unsorted rock material Ground Moraine- Carried along the bottom Lateral Moraine- Long lines of rock pieces along the valley sides Medial Moraine- When two glaciers come together and there lateral moraines joins together.
 * Glacier Movement