How Landforms ChangeScience Book pg. 78-84

Changes caused by windWeathering – the process of wearing away rocks by natural means.

Wind can cause weathering to rocks and cause rock formations to change .

Wind can also blow small pieces of rock around and cause piles of sand called sand dunes.

Sand dunes are found in deserts, beaches, and on lake shores.

Changes Caused by Moving WaterErosion – the process of moving sediment by wind, water, or ice.

Water can cause erosion by digging canyons, changing the path of a river, and eroding river banks.

This erosion occurs when the water knocks pieces from rocks and moves the sand and silt from one place to another and then it is deposited or dropped.

Erosion and DepositionMoving wind or water has energy and can move sediment.

Fast moving water causes a large amount of erosion and slow moving water causes a small amount of erosion.

Rain and ocean waves are two forms of water that causes erosion.

RainRain causes erosion by falling on bare hills and mountains and splashing away the soil.

As it runs downhill it moves faster and it carries the soil away and over time forms gullies or ditches.

Ocean WavesOcean waves cause erosion from their constant banging into shorelines and cliffs.

The waves carry broken pieces of rock away and cause the cliffs to get steeper.

DepositionDeposition – when sediment is dropped into a new location by wind or water.

Ocean waves and rivers can cause deposition.

Ocean Waves cause depositionOcean waves cause deposition by bringing sand onto the beach and dropping it.

Rivers cause deltasRivers can deposit sediment at its mouth (where it empties into the ocean).

As the river meets the ocean it slows and deposits the sediment it was carrying.

This landform is called a delta which is a new area of land at the mouth of the river.

Flood PlainsFlooding water can deposit sediment near a river. This is caused when heavy rains cause a river’s water to go over the banks.

When the water goes back down the sediment that went over the bank stays in place and is rich in nutrients.

This creates good soil for growing crops.

SinkholesWater that is underground can weather and erode soft rocks. This erosion can cause caves to form underground.

Often the roof of the cave collapses due to the weight of material above it.

If the cave is near the surface a large hole called a SINKHOLE may open suddenly.

Most sinkholes occur in Florida where limestone is common.

LandslidesGravity can also cause erosion and deposition.

When gravity makes soil, mud, and rocks move quickly down a hill then a landslide has occurred.

Landslides can happen suddenly, especially after earthquakes and heavy rains.

PlantsPlants can cause weathering and erosion.A plants roots can grow down into cracks in the rocks and become large enough to break pieces from the rock.

Plants also help hold soil and sand in place which prevents erosion.Examples: farmers plant clover in unused fields, plants growing on sand dunes hold down the sand.

Providence Canyon formed when plants were removed and water runoff from nearby farms eroded the land.