Vocab #3 Tools A B weathering The chemical or machanical proces by which rock is gradually broken down mechanical weathering The actual breaking up or physical weakening of rock by forces such as ice and roots frost wedging Where water gets into a crach in the rock then turns into ice, expanding and eventually breaking off the rock chemical weathering The process by which the actual chemical structure of the rock is changed acid rain Rain whose high concentration of chemicals eats away at the surface of stone and rock is a type of chemical weathering erosion The movement of weathered materials agents of erosion wind, water and glaciers sediment usually gravel, soil and sand delta The build up of sediments at the mouth of a river (triangle) dust bowl The Dust Bowl was the area near the great plains in the 1930s when famers plowed too much land, which therefore meant less plants. When you have less plants, the dirt is more supsptable to being carried of by the wind because there is nothing to hold them down. Massive dust storms covered this area, and it is now known as the dust bowl. loess Fine-grained, mineral-rich loam, dust or silt deposited by wind glaciers A huge, slow moving mass of snow and ice moraines A ridgelike mass of rock, gravel,sand and clay carried and deposited by a glacier "U" shaped valleys valley formed by a glacier "V" shaped valley valley fomed by a river " Ice Age" The ice age occured when a third of the earth's water became trapped in glaciers and when these glaciers melted the earth became colder. Long periods of these cold temperatures was called the Ice Age. 4 Ice Ages have occured in the last 600 million years, the last one ocuuring about 18,000 years ago. Continental glaciers/ice sheets * def eeded valley/alpine glaciers Alpine glaciers are those found at the top of mountain ranges and slowly move downhill by the force of gravity.