 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.

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.

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.

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).

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.

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.