Transcript Erosion PPT
The Earth’s surface changes over time due to weathering and erosion. The Earth’s surface is always changing! Weathering The breakdown do the materials of Earth’s crust into smaller pieces. Water causes weathering What evidence of weathering do you see in this picture? Ice causes weathering Describe how ice causes weathering? Temperature changes cause weathering. Why did the outer layer of the rock crack? Erosion The process by which water, ice, wind or gravity moves fragments of weathered rock and soil. Where did the forces of erosion remove material? Erosion is Movement of Sediment! • The process known as Erosion is gradually wearing down the surface of the earth. • Erosion moves weathered rock and soil (sediment) from one place to another. • Erosion carves the Earth's surface creating canyons, gorges, and even beaches. • Erosion also acts below the surface creating caves. Which force of erosion carved this feature? Be specific! Wind Erosion • As the wind blows it picks up small particles of sand/sediment and blasts large rocks with the abrasive particles, cutting and shaping the rock. • The intensity of wind erosion is determined by: – – – – Sum (amount) Speed Slope Surface Wind Erosion Water Causes Erosion • runoff, rivers and, streams Water causes Erosion When rain falls to the Earth it can evaporate, sink into the ground, or flow over the land as Runoff. When it flows over land, erosion occurs. Runoff picks up pieces of rock and "runs" downhill cutting tiny grooves (called rills) into the land. Water causes Erosion How much erosion takes place is determined by the: – – – – Sum (amount) Slope Speed Surface Can you act increasing and decreasing the four S’s? Ice Causes Erosion Glaciers wear down the landscape; by picking up and carrying debris that moves across the land along with the ice. Ice Causes Erosion Glaciers can pick up and carry sediment that ranges in size from sand grains to boulders bigger than houses. Moving like a conveyor belt and a bulldozer, a single glacier can move millions of tons of material! Ice Causes Erosion How much erosion takes place is determined by the: • **Sum (Glaciers are massive!) • Slope • Speed • Surface Gravity causes erosion Creep, Slump, Landslides, Mudslides, and Avalanches. Slower Faster These are examples of mass movement landslide clip.mpeg (or called mass wasting) Gravity causes Erosion How much erosion takes place is determined by the: • • • • Sum **Slope Speed **Surface Plants CAN CAUSE weathering Plants CAN PREVENT erosion Deposition Rock particles that are picked up and transported during erosion will ultimately be deposited somewhere else Deposition is the process by which sediments (small particles of rock) are laid down in new locations. • Together, Erosion and Deposition build new landforms. • Deltas • Canyons • Meanders • Floodplains Delta Where rivers meet the ocean is called the mouth of the river. Soil and dirt carried by these rivers is deposited at the mouth, and new land is formed. The new, soil-rich land is known as a Delta Canyons This simple animation provides you with a visualization of how the Colorado River has "downcut" into the rock layers of the Grand Canyon. Canyons are large valleys created by a river or stream. How long it took to carve the Grand Canyon is debated by geologists. Some estimates are between 6 and 8 million years, which is very recent by comparison. Meanders Meandering streams wander side to side as they constantly seek out the lowest elevation. This constant motion creates a series of S-shaped “loops”. Meanders Stream Velocity varies from one side to the other side of the “S”, resulting in erosion in some places and deposition of sediments in others. Floodplains • Floodplains form along the banks of mid-order streams and larger rivers. • These are low-lying areas along the sides of a river channel that have regular times of heavy waterflow to cause the river to spill over and flood the land.