Earth Science Chapter 9 – Erosion and Deposition

Erosion – _____

Caused by (agents):

  • _____
  • _____
  • _____
  • _____
  • _____

Sediment – _____

Deposition – _____

Gravity – force that moves rock and other materials downhill. Causes a mass movement – any 1 of several processes that move sediment downhill

  • Landslides – _____
  • Mudflows – _____. Often occur in dry areas after a heavy rain.
  • Slump – _____. The bottom falls out from under the soil.
  • Creep – _____.

Water Erosion

Runoff – _____ (excess). Depends on 5 main factors

  • Amount of rain received
  • Vegetation (remember activity from last chapter to prevent erosion?)
  • Type of soil
  • Slope of the land
  • How people use the land
  • Increase runoff, increase erosion
  • Causes

1. Rills and gullies – rills are _____ and gullies are _____. Water flows through it and it moves sediment

2. streams and rivers – stream is _____, they flow together to make a river

3. tributaries – _____

Erosion by rivers causes

  • _____
  • _____
  • _____ – wide flat area of land along a river
  • _____ – large bend in a river
  • _____ – meander that has been cut off from the rest of the river

Deposits by rivers make:

  • Alluvial fans – _____
  • Deltas – _____
  • Add to a flood plain

Groundwater erosion

  • Groundwater is _____
  • Cause erosion through chemical weathering
  • Water + carbon dioxide = _____
  • Deposits cause stalactites and stalagmites (c=ceiling and g=ground)
  • Limestone near groundwater at the surface can wear away and the overlying ground can fall through = sinkhole

How water erodes

  • Most sediment falls into a river as a result of mass movement and runoff. It can erode from the bottom of sides of a river.
  • Abrasion – _____ (think about sand in the waves at your feet at the beach).
  • Amount of sediment that a river carries is a _____
  • Ability of water to do this depends on

1. river slope – increase slope _____ flow and how much it carries

2. volume of flow – increase amount of moving water (such as a flood), increase _____

3. shape of streambed – contact with sides and bottom of river _____ river flow. The rougher the sides the more turbulence there is (water flowing in many directions)

4. water moves slowly at the sides and sediment is deposited. If a river curves water moves fastest around the outside (erosion) and slowly around the inside (deposition).

Glacier – large mass of ice that moves slowly over land

  • Continental glacier – _____. When they cover very large parts of the Earth it is an ice age. Last one was 10,000 years ago.
  • Valley glacier – _____.
  • Form only in areas where more snow falls than melts. Once depth of snow and ice reach more than 30-40 m brevity begins to pull glacier downhill.

Shaping the land

  • Plucking – _____.
  • Abrasion creates u-shaped valleys as rocks abraid the land underneath it.
  • Till – _____
  • Moraine – _____
  • Kettle – _____
  • Lakes
  • Drumlin – _____
  • Cirque – _____
  • Arête – _____
  • Horn – _____
  • Fiord – _____

Erosion by waves

  • Impact of wave can break apart rocks over time, making small cracks larger
  • Abrasion by sand carried by wave can erode the rocks
  • Headland – _____
  • Sea stack
  • Cliff
  • Sea cave
  • Sea arch
  • Beach
  • Spit
  • Sandbar

Wind – causes erosion by _____ and _____ (weakest agent)

  • Sand dune – _____ (crescent or star shaped depending no how the wind blows)
  • Deflation –_____
  • Loess – _____