Question

Compare and contrast – in detail – the type of continental margin found along the west coast of North America, versus the type of continental margin found along the east coast of North America. Be sure to describe the important continental margin features, and indicate the relative width of the continental shelf and steepness of the slope/rise.

13. What kind of fault is represented by the Eltanin and Romanche fracture zones? 14. a) Describe the physical relationship between the Mid-Atlantic Ridge, the Mid-Indian Ocean Ridge, and the East Pacific Rise. (What do they have in common? Are they connected, and if so, how?) What appears to be the geographic relationship between the Carlsberg Ridge and the Red Sea trough? Based solely on plate tectonics, do you think the Red Sea will be narrower or wider a million years from now?

Answer 1

1. The continental margin of west coast of North America is a convergent plate boundary, where the oceanic plate subducts underneath the North American continental plate. In contrast, the east coast is a passive margin, with no subduction taking place. As a result, the east coast continental shelf is relatively wide, and the slope is gentle.

13. The Eltanin and Romanche fault zones are a series of transform faults.

14. a) All the ridges mentioned above are divergent plate boundaries in the ocean. They are geographically separate, but are related in the way that they are all sources of new oceanic crust being formed.

b) The Red Sea trough lies north of the Carlsberg ridge, and is a sort of extension of the Carlsberg ridge. It meets the Aden ridge and the East African rift at the Afar triple junction. The Red Se will be wider if the current trend of rifting continues, but the East African rift to the south is also a divergent plate boundary, and one of these rifts is bound to fail, since there is no room for both rifts to continue.