Erosion

Objectives: Explain the difference between erosion and deposition.Compare and contrast erosion by gravity, water, glaciers and wind.

Erosion● The process that wears away Earth’s surface

materials and moves them from one place to another.

The causes of erosion are called AGENTS. There are 4 agents of erosion.

● Gravity – is the force that pulls all objects down hill.

● Wind- Erodes surfaces by abrasion.● Water- flowing water carries sediments

from one place to another.● Glaciers-push and drag sediments and

deposit them elsewhere.

Deposition●When sediments are relocated

and dropped by the erosion process.

Water flowing over Earth’s surface erodes the land by wearing away rock and moving weathered rock and soil. The sediments that are moved is called load.

The volume of water flowing through a stream in a given amount of time is known as stream discharge. Rain and melting snow affects amount of discharge. The more discharge, the faster the stream flows.

When a stream overflows, the excess water rises on the area of land next to the stream. This slows the pace of the stream and helps deposit sediments.

A delta is formed when sediments are deposited as a river empties into an ocean, gulf or lake.

Nile Delta

Named after the Greek letter Delta = ∆

An alluvial fan is made by sediments being dropped as a river flows on a level surface and slows down.

Beach ErosionHigh and low tides take sediments out and

brings in new sediments. The shore is in a constant state of erosion and deposition.

Wind⬜ Another agent of erosion. When air moves, it

picks up loose materials and transports it to another place.

⬜ Wind carries and deposits sediments over large areas.

⬜ It is different from other erosional forces because it can’t pick up heavy sediments.

Abration⬜ When the surface of a rock gets scraped and polished by wind blown sediments. (Sand Blasted)

Glaciers• A large mass of ice or snow moving on land,

under its own weight, and with the help of gravity.

• A glacier is an agent of erosion- it can carry sediments, drag rocks along, and push down trees. It changes the surface of the land.

Mass Movement●Any type of erosion that happens as

gravity moves material down slope.

●The 4 types of mass movement are creep, slump, rock falls and landslides.