True or False: The Earth’s surface has stayed the same for thousands of years

The Earth’s surface is always changing!

Weathering The breakdown of the Earth’s crust into smaller pieces.

Water causes weathering What evidence of weathering do you see in this picture?

Wind causes weathering What evidence of weathering do you see in this picture? Why wasn’t this mass of land weathered away?

Ice causes weathering Describe how ice causes weathering?

Erosion The process by which water, ice, wind or gravity moves fragments of rock and soil. What evidence of erosion do you see in these pictures?

Erosion is Movement of Sediment! This process, known as Erosion, is gradually wearing down the surface of the earth. Erosion is the process by which weathered rock and soil (sediment) are moved from one place to another. Erosion carves the Earth's surface creating canyons, gorges, and even beaches. What do you think has caused this rock to look this way?

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.

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 into the land.

Water causes Erosion How much erosion takes place is determined by the amount of slope on the surface and the speed of the water moving over the surface, and the amount of water moving over the surface.

Ice Causes Erosion Glaciers can wear down the landscape by picking up and carrying debris as the glacier moves across the land.

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 size of the glacier, the speed the glacier is moving, and the slope/surface of the land it is moving on. Size, speed, slope, and surface….where have you heard those words before?

Gravity causes erosion Creep, Slump, Landslides, Mudslides, and Avalanches. landslide clip.mpeg These are examples of mass movement (or called mass wasting) SlowerFaster

Gravity causes Erosion How much erosion takes place is determined by the: **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. 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. Canyons are large valleys created by a river or stream.

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.

Now its your turn…

Today you are going to become earth scientists studying a model of a world-famous landform: The Grand Canyon.

The canyon is almost 2 km deep in places, and geologists are very curious about how it formed. Because the Grand Canyon can't be brought into the classroom, a model of it can be created using a stream table.

You will notice stream table at the edge of several tables with a bucket on the floor to catch water that flows out of the stream table. On each stream table you will notice a ruler with a cup placed on top. This cup represents your water source such as the Colorado River in the bottom of the Grand Canyon. The earth material represents a small section of the earth's surface, and the 1 liter of water that they will run through the system represents thousands of years of water flowing over the earth.

Please remember that you will pour only 1 cup of water through your stream table system. Do not touch the tray or shake the desks once the water starts flowing. Before your start, sketch a before picture in your science journal. We want to be able to see your results.

You should be able to different landforms. Landforms are shapes of the earth's surface. Some landforms to look for during your stream table investigation are valleys, flood plains, meanders, deltas, and the mouth of the stream. Make sure that you document them if you do see them!

Remember, the purpose of this investigation is so that you can see for yourselves in a small way how water runs over the earth and wears the earth away. This process is called erosion. Some materials, like loose sand and soil, erode very quickly, but other materials, like granite and sandstone, erode more slowly. The cutting of the canyon in the stream table model is an example of the process of erosion.