Erosion and DepositionErosion and Deposition• Erosion – is the

process by which weathered rock and soil particles are moved from one place to another.

• Deposition – Sediments are laid down in a new location.

Five Factors of ErosionFive Factors of Erosion

• Gravity• Wind• Running Water• Glaciers• Waves

GravityGravity

• Mass Wasting- the downhill movement of sediments caused by gravity.

• Landslides• Mudflows

SlumpSlump• A block of Rock or soil moves down a steep

slope with its upper surface tilted backwards as it falls

Slow Mass WastingSlow Mass Wasting

• Earth Flows and Soil creep are two examples of slow mass wasting

Wind ErosionWind Erosion• Deflation – Wind

removes loose materials such as sand, silt and clay

• Abrasion – Sand Blasting

Features formed by Wind ErosionFeatures formed by Wind Erosion• Dunes – Wind blown

sand is deposited near rock and bushes in desert areas

• Loess – Very fertile, light in color, many meters thick consisting of sand and silt

How can you curtail wind erosion?How can you curtail wind erosion?

• Bushes, trees and fences act like barriers to block the wind

Major Cause of ErosionMajor Cause of Erosion• Running Water – Water turns into

runoff as it travels, picking up weathered rock particles and making small grooves in the ground known as Rills. As the Erosional process continues, the grooves become larger and are now called “Gullies.”

Factors that affect RunoffFactors that affect Runoff

• Amount of rainfall

• Plant Growth

• Shape of the Land

Life Cycle of a RiverLife Cycle of a River• Immature River –

Early stages of development

• Mature River – In development for thousands of years

Life Cycle of a RiverLife Cycle of a River

• Meandering – A river begins to curve and wind due to erosional forces

Oxbow LakeOxbow Lake

• Large “U” shaped bends forming small lakes

As a river leaves a mountain and runsout onto a flat plain its speed decreases and its sediments are spread out in a fan like shape called an Alluvial Fan

Delta - large amounts of sediments deposited at the mouth of a river that flow into a lake or ocean

Rivers overflow their banks after heavy periods of rain or thaw And leave fine sediment deposits

Levees are formed from larger particles that settle of the sides of rivers

Glacial Ice erodes away rock as it moves by abrasion and plucking away at the rock beneath it

Rocks and soil that are deposited by the glacier are called “Till”

After a Glacier melts and retreats, it leaves behind till, which forms a ridge called a “Moraine”

An oval shaped mound of Till is called a “Drumlin”

Melt water deposits are left by a Valley Glacier stops moving

Out wash Plains are fan shaped and formed In front of a Terminal Moraine

As a Iceberg melts it leaves its deposits on the Ocean Floor

Kettle Lakes (Great Lakes) form in two ways:1) Glacial Till deposits form in river channels causing water to form lakes2) Blocks of ice melt away leaving sediments behind and a depression forms after the ice melts