Erosion and Deposition

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Lynne Long
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1 Erosion and Deposition Erosion Sediment natural forces move rock/soil from one place to another. gravity, water, wind, glaciers, waves are causes material moved by erosion Deposition when erosion lays down sediments works with weathering & erosion involved in wear down and build up of Earth s surface never ending cycle Runoff & Erosion Runoff Water Erosion major agent of erosion: moving water all remaining water on Earth s surface may cause sheet erosion (thin layer over land) 1

Rills Gullies tiny grooves in the soil large groove, or channel, in soil that carries runoff only flow after it rains

brooks a large stream Amount of runoff depends on 5 factors: 1. amount of rain in an area 2.

shape of the land: steep land has more runoff than flatter 5.

2 Rills Gullies tiny grooves in the soil large groove, or channel, in soil that carries runoff only flow after it rains may dry up Streams Rivers channel where water constantly flows down a slope rarely dries up also called creeks or brooks a large stream Amount of runoff depends on 5 factors: 1. amount of rain in an area 2. vegetation: grasses, shrubs, trees reduce runoff 3. type of soil 4. shape of the land: steep land has more runoff than flatter 5. how people use the land more runoff = more erosion River Systems Tributary Drainage Basin stream that flows into a larger stream ex. small creek that flows into a large river is a tributary to that river land area where a river and its tributaries collect water 2

Divide Erosion by Rivers high ground between two drainage basins ex.

oxbow lakes V Shaped Valleys Waterfalls form when rivers erode along steep slopes

flat, wide area of land along a river Meanders looplike bend in a river (snake

3 Divide Erosion by Rivers high ground between two drainage basins ex. Continental Divide rivers create: valleys, waterfalls, flood plains, meanders, & oxbow lakes V Shaped Valleys Waterfalls form when rivers erode along steep slopes occurs when river meets an area of rock that is hard & erodes slowly Flood plains flat, wide area of land along a river Meanders looplike bend in a river (snake like) Oxbow lake meander that has been cut off from a river (ushape) may form when a river floods 3

4 Erosion, Deposition Notebook.notebook ` Deposits by Rivers deposition creates: alluvial fans & deltas can also add soil to a river s flood plain Alluvial Fan wide, sloping deposit of sediment formed where a stream leaves a mountain range shaped like a fan 4

dioxide to form a weak acid = carbonic acid weathers limestone forms deposits from roof/floor of caves Stalactite Stalagmite Karst Topography

5 Delta landform made of sediment deposited where a river flows into an ocean or lake Groundwater Erosion & Deposition Groundwater water soaks into ground when it rains underground water affects the shape of the land causes erosion through chemical weathering combines with carbon dioxide to form a weak acid = carbonic acid weathers limestone forms deposits from roof/floor of caves Stalactite Stalagmite Karst Topography deposit on roof of cave cone shaped deposit on floor of cave landscape where limestone is near the surface characterized by caverns, sinkholes, and valleys 5

Glaciers Glacier large mass of ice that moves

snow/ice build up high in mountain valley

much of a continent or large island much

6 Glaciers Glacier large mass of ice that moves slowly over land two types: valley (alpine) and continental Valley/Alpine Glacier Continental Glacier long, narrow forms when snow/ice build up high in mountain valley usually move down valleys cut by rivers covers much of a continent or large island much larger than valley covers 10% of Earth s land Antarctica & Greenland 6

Ice Ages continental glaciers covered large parts of Earth s surface last ice age

area move where more snow falls than melts snow builds year after year pressure on

flow a few cm to m each day continental flow in all directions Glacial Erosion

7 Ice Ages continental glaciers covered large parts of Earth s surface last ice age lasted 70,000 years and ended 10,000 years ago How glaciers form & only form in area move where more snow falls than melts snow builds year after year pressure on bottom layers turns snow into ice valley g. flow a few cm to m each day continental flow in all directions Glacial Erosion Plucking two processes: plucking and abrasion as glacier flows, it picks up rocks weight of ice breaks rock carries rocks as it moves 7

Abrasion Deposition gouges, scratches bedrock as glacier drags rocks

Moraine deposits directly on surface many different sized particles ridge

Long Island in New York Kettle small depression that forms when ice is

8 Abrasion Deposition gouges, scratches bedrock as glacier drags rocks glacier melts, deposits sediment eroded from land creates landforms Till Moraine deposits directly on surface many different sized particles ridge formed when till is deposited at edge of glacier ex. Long Island in New York Kettle small depression that forms when ice is left in till ice melts, kettle remains often fills with water forming ponds/lakes ex. the Great Lakes 8

Waves How waves form waves get energy from blowing wind energy causes water particles to

approach shore, it drags on the bottom friction causes waves to slow Erosion by Waves

breaks apart rock also erode by abrasion sediment picked up by wave wears rock like

resists waves Landforms waves hit same area over and over erodes base of land along

9 Waves How waves form waves get energy from blowing wind energy causes water particles to move up and down water particles don t move forward only form of the wave moves as waves approach shore, it drags on the bottom friction causes waves to slow Erosion by Waves major erosion force along coasts erode land by impact large waves hit with great force breaks apart rock also erode by abrasion sediment picked up by wave wears rock like sandpaper energy of wave depends on headland part of shore that sticks out harder rock; resists waves Landforms waves hit same area over and over erodes base of land along steep coasts places of soft rock form sea caves also forms sea arches; pillar of rock above water 9

10 Erosion, Deposition Notebook.notebook Deposits Beach area of wave washed sediment along coast usually sand comes from rivers that flow into ocean some are coral/shells piled up waves shape coast thru erosion & deposition as waves slow, they drop sediment similar to river deposition forms beaches Longshore Drift movement of sediment caused by waves hitting shore at angles forms a spit Spit beach that projects like a finger into water 10

the particles that can be picked up doesn

11 Erosion, Deposition Notebook.notebook Wind How Wind Causes Erosion Deflation weakest agent of erosion effective in deserts process by which wind removes surface materials main way wind causes erosion stronger the wind, larger the particles that can be picked up doesn t usually greatly affect land creates areas of rock fragment called desert pavement produces bowl shaped hollows called blowouts abrasion polishes rock 11

12 Deposits from wind erosion forms: sand dunes & loess deposits Sand Dunes Loess deposit of windblown sand different shapes & sizes can move over time fine, wind deposited sediment helps to form fertile soil Gravity Force that moves rock downhill. Landslides rock/soil slide quickly down a slope Mass Movement caused by gravity different types: *Landslides *Mudslides *Slump *Creep Mudflow rapid downhill movement of water, rock/soil occurs after heavy rains in a dry area 12

13 Erosion, Deposition Notebook.notebook Slump Creep mass of rock/soil slips down a slope occurs when water soaks the base of a mass rich in clay slow downhill movement of rock/soil often results from freezing/thawing 13

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15 Attachments Meanders, erosion, deposition animation Animations: erosion and depositon Coastal Erosion

Chapter 3 Erosion and Deposition. The Big Question:

Chapter 3 Erosion and Deposition The Big Question: 1 Design a way to represent and describe the 4 types of mass movement. You may use pictures, diagrams, list, web, chart, etc 2 Chapter 3: Erosion and