Agents of Erosion & Deposition                                                                      Agents of Erosion & Deposition By: Myesha & KaShawn

Shoreline Erosion & Deposition Shoreline- where land & a body of water meet Beach- an area of a shoreline made up of material deposited by waves Longshore current- movement of water near & parallel to the shoreline

-The wind from storms usually produces the large waves that cause shoreline erosion. -Waves break when they enter shallow water, becoming surf. -Beaches are made of any material deposited by waves. -Sandbars & spits are depositional features caused by long shore currents. -Sea cliffs, sea caves, sea arches, & sea stacks are coastal formations caused by erosion.

This is an example of shoreline erosion.

Wind is an important agent for erosion & deposition in deserts & along coastlines. Saltation is the process of the wind bouncing sand grains downwind along the ground. Deflation is the removal of materials by wind. If deflation removes all fine rock materials, a barren surface called desert pavement is formed. Abrasion is the grinding & wearing down of rock by other rock of sand particles.

Wind Erosion & Deposition Saltation- movement of sand size particles by a skipping & bouncing action in the direction the wind is blowing Deflation- lifting & removal of fine sediments by wind Abrasion- grinding & wearing down of rock surfaces by other rock or sand particles Dunes- mounds of wind deposited sand Loess-thick deposits of windblown fine grain sediments

Before After

Erosion & Deposition by Ice Icebergs- large pieces of ice that break off an ice shelf & drift into the ocean Crevasse- a large crack that forms where the glacier picks up speed or flows over a high point Glacial drift- the general term used to described all material carried & deposited by glaciers Stratified drift-rock material that has been sorted & deposited in layers by water flowing from the melted ice Till- the second type of a glacier drift

Because glaciers are very heavy and have the ability to move cross the earth’s surface, they are capable of eroding moving, and depositing large amounts of rock materials. One common type of alpine glacier is a valley glacier which form from valleys originally created by stream erosion. These glaciers flow slowly downhill, widening and straightening the valleys into broad U-shapes as they travel. Continental glaciers continue to get larger, spreading across entire continents. Continental ice sheet is the largest type of glacier. The thickness of the ice and the steepness of the slope determines how fast a glacier will move. Glaciers move by 2 different methods: 1) they move when the weight of the ice causes the ice at the bottom to melt.(the water from the melted ice allows the glacier to move forward, like a partially melted ice cube moving across the kitchen counter. 2)solid ice crystals within the glacier slip over each other, causing a slow forward motion.(like placing a deck of cards on a table and tilting it.            

There are main types of glacial deposits stratified till some of the landforms deposited by glaciers include outwash plains and moraines. Outwash plain- streams carry an abundance of sorted material which is deposited in front of the glacier in an broad area. Moraines- are the most common till deposits which generally form ridges along the edges of glaciers.

Gravity’s Effect on Erosion & Deposited Mass Movement- the movement of any material, such as rock, soil, or snow, down slope Rock Fall- when a group of loose rocks falls down a steep slope Landslide- the sudden & rapid movement Mudflow-a rapid movement of a large mass of mud Creep- the extremely slow movement of material down slope

Mass movement is controlled by the force of gravity and can occur rapidly or slowly. The angel of repose is the steepest slope at which loose material will remain at rest . (if the slope on which a material rest is less than the angle of response, the material will stay in place. If the slope is greater than the angle of repose, the material will move down slope) Rapid mass movement – the most destructive mass movements occur suddenly and rapidly Rock falls, landslides, and mudflows are all types of rapid mass movements Slow mass movement- happen little at a time creep is an example