Question

Explain the theory of Plate Tectonics. b) How does it account for the Mid-Atlantic Ridge? c) How does it account for volcanic island chains like Hawaii?

Answer 1

Answer:

A) The continents and ocean basins undergo continuous change. Both are parts of lithospheric plates that move against each other. B) Divergent plate in Mid-Atlantic Ridge with material flowing into the ocean. C)  A plate moved over a stationary site of magma upwelling "Hot Spot" and created a volcanic island chain over the time

Explanation:

A) The basic thought is, that instead of being permanent fixtures of the earth's surface, the continents and ocean basins undergo continuous change. Both are parts of lithospheric plates that move against each other, and in the process new crust is created at midoceanic ridges (spreading centers), and old crust is consumed at convergent plate boundaries (subduction zones).

B) There are basically three different types of plate boundaries:

Divergent boundaries -- where new crust is generated as the plates pull away from each other.

Convergent boundaries -- where crust is destroyed as one plate dives under another.

Transform boundaries -- where crust is neither produced nor destroyed as the plates slide horizontally past each other.

The best known of the divergent boundaries is the Mid-Atlantic Ridge. This submerged mountain range, which extends from the Arctic Ocean to beyond the southern tip of Africa, is but one segment of the global mid-ocean ridge system that encircles the Earth.

C) The linear arrangement of many seamounts indicates that they formed because the plate moved over a stationary site of magma upwelling, a so called mantle "Hot Spot".  Seamounts are submarine volcanoes that may finally build above the water level, in which case they are called islands.  If seamounts rise above sea level (due to buildup of material in a cone or upwelling mantle pushes up plate), they are subject to wave erosion and colonization by reefs, with both processes tending to create a flat top on the original volcanic cone.