Major landforms like mountains and plains are shaped by tectonic plates and erosion from water, wind, and glaciers over millions of years. Glaciers can scoop out basins that become lakes when the ice melts, and water erosion from rivers and streams carves out valleys and canyons as it flows downhill and joins larger rivers on its way to the ocean. Bodies of water like lakes and rivers have significantly impacted human settlement and development.

1. Land and Water

2. Major Landforms Many Forces shape the land. Tectonic Plates Erosion Glaciers Erosion Erosion

3. 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.

4. Erosion Erosion is the process of wearing away rock and soil. Erosion is caused by water, wind, and glaciers.

5. Water Erosion Creates deep valleys and canyons. Example: The Colorado River carved the Grand Canyon

6. 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.

7. 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

8. Bodies of Water Waterways have been formed by glaciers and by the flow of water

9. 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.

10. 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.

11. 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.

12. More About Rivers The Mississippi River is the 2 nd 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

13. Why It Matters…. Landforms and bodies of water influence how and where we live!