Earth’s Land

1. Earth’s Land Landforms are shapes on the planet’s surface (mountains, valleys, plains, islands, hills, peninsulas, etc.) Mountains are over 2,000 feet in elevation.

2. Plate Tectonics • The Earth’s surface is divided up into large sections called plates. • Plate tectonics theory states that the Earth’s surface is divided up into a dozen or so slow moving plates. Continents are located along these plates along with the ocean floor.

3. Plate Tectonics • Earth’s plates sometimes collide, slide, or separate from each other. • The German scientist, Alfred Wegener, developed the continental drift theory; which states all the continents were once part of a single supercontinent.

4. Plate Tectonics Continued • When plates collide, either mountain rages or ocean trenches are formed. • When plates separate, lava often is released through the Earth’s crust, thus forming mid-ocean ridges or underwater mountains (ex. Iceland). • When plates slide past each other, earthquakes can occur (fault lines).

5. Forces on Earth’s Surface • Weathering is the process by which rock is broken down into smaller pieces. • Erosion is the movement of sediment from one location to another. Wind, ice, and water all cause erosion.

6. Lesson Visuals • Page 36 – Earth’s Plates. • Page 38 – Plate Movement. • Page 39 – Wind Erosion. • Page 40 – Water Erosion. • Page 41 – Living With Landforms. • Pages 42/43 – Ring Of Fire, Chart, Mount St. Helens.