The theory of plate tectonics is supported by . The Eurasian and African plate are pushed away from the North and South American Plates at the . is where rocks are carried back into the mantle of the earth. iron can be magnetized by the magnetism of the earth. Subduction of the ocean floor occurs in . Respond to the following based on your reading. Why have rocks older than 200 million years never been found in the oceans? Explain how the movement of tectonic plates is responsible for this recycling of the ocean floor.

1. ridges and trenches (either answer is acceptable)

2. mid-atlanitc

3. subduction zone

4. molten

5. oceanic trenches

Explain:

6. Rocks in the ocean eventually get subducted back into earths mantle due to slab pull. New rocks form at mid-ocean ridges as ridge forces two plates to diverge.

increase soil erosion                                             reduce soil erosion

cattle grazing                                                         hydroseeding

deforestation                                                         contour plowing

                                                                                planting vegetation

plant roots basically hold the top soil

together and stop soil erosion because

in such situation top soil is not removed

during flood but cattle grazing causes

soil erosion because cattle consume the

grasses and herbs and top soil is exposed.

same situation occurs because of

deforestation, the trees and plants are cut

down to expose top soil which causes soil

erosion