Forces of Change

1. Forces of Change Rose Wright, Elizabeth Robinson, Cody Stoelzle, Don Harris

2. A Layered Planet • core—the very center of Earth; two parts: inner core, which is made of solid metals due to the pressure on it, and the outer core made of liquid metal. • mantel—a thick layer of hot, dense rock which is partially melted. • crust—a rocky shell forming the earth’s surface

3. Plate Movement continental drift: theory that the continents were once joined and then drifted apart. Thus it is also believed that the plates float freely upon the mantel. plate tectonics: all of the physical processes that create Earth’s physical features. magma: molten rock from the mantel.

4. Internal Forces

5. Colliding & Spreading Plates • subduction—process by which two plates collide and the lighter of the two sinks beneath the other. This process can also cause mountains, because the lighter one pushes the other upwards. • accretion—the pieces of Earth’s crust come together slowly as the sea plates slide under continental plates. This is the opposite of spreading, which causes trenches. Himalayas: a mountain range south of Asia being the tallest in the world

6. Folds & Faults • folds—bends in the layers of rock, similar to subduction but involving layers of the same mass. • faults—cracks in the earth’s crust • faulting—when land is folded and reaches a breaking point. The land then shatters and the shards then grind against each other creating small earthquakes. San Andreas Faultline; one of the most famous fault lines in the world, caused by faulting. The scar you see here is from the last time a faulting happened in this area.

7. Earthquakes—caused by faulting • Kobe—place in Japan where disasterous earthquakes have happened. • San Francisco—city in California; site of many earthquakes. Most famous being a massive fault shift that tore the city apart. • Ring of Fire—one of the most earthquake- and volcanic-prone areas on the globe.

8. Volcanic Eruptions • One of the biggest and fastest-acting forces to change Earth’s features.

9. External Forces of Change Weathering: a force that breaks down rocks Erosion: wears away Earth’s surface by wind, glaciers, and moving water

10. Wind Erosion • Movement of dust, sand and soil. It’s a constant force of change responsible for some of the most obscure geographical features.

11. Glacial Erosion • moraines—rock and debris left over when glaciers melt. • Greenland—a northern, Scandinavian country almost completely covered in ice. • Antarctica—continent much like Greenland, covered in glacial sheets that are increasingly receding. glaciers—large bodies of ice that move across Earth’s surface

12. Water Erosions Grand Canyon: product of water erosion • Water erosion begins when spring- and rain-water flow down in streams that cut through land. • This force is responsible for the Grand Canyon