Land and Water

Major Landforms

Many Forces shape the land.

Tectonic Plates

Glaciers

Erosion

Tectonic Plates

• Are underneath the Earth’s surface.• Are huge slabs of slowly moving rock.• Over 50 million years ago, they pushed together and

caused rocks to break and move.• Rocky Mountains and Appalachian Mountains were

formed by tectonic plates.

Erosion

• Erosion is the process of wearing away rock and soil.

• Erosion is caused by water, wind, and glaciers.

Water Erosion

• Creates deep valleys and canyons.

• Example: The Colorado River carved the Grand Canyon

Wind Erosion

• Blows sand against rock and wears it away. • Blows away dry soil when there are few plants to hold

down the soil.• Example: Wind erosion widened the Grand Canyon.

Glacier Erosion

• Glaciers are huge pieces of slowly moving ice.

• They push soil and rocks as they move.

• They flatten some areas and leave piles in others.

Hills

Valleys

Plains

Bodies of Water

• Waterways have been formed by glaciers and by the flow of water

Lakes

• Glaciers scooped out soil and rocks to form basins.– Basin: an area with a low center surrounded

by higher land.

• When glaciers melted, water stayed in the basins.

More About Lakes

• If water flows faster into low areas than it can leave, lakes can form.

• Some lakes drain water through rivers.

• Some the water seeps into the ground.

• Utah’s Great Salt Lake is very shallow and the water evaporates.

Rivers

• Rivers form as water moves over land from a high area to a lower area.

• Water flows downhill in creeks and streams.

• Creeks and streams join up with a river, which flows to the nearest ocean.– Rivers west of the Rocky Mountains flow west

instead of south like the Mississippi River does.

More About Rivers

• The Mississippi River is the 2nd largest river in North America.

• Earliest settlers settled along rivers.– Provide water for drinking and farming– Help people travel and move goods– Steady flow creates power to run machines

Why It Matters….

Landforms and bodies of water influence how and where we live!