Question 4 of 15 (worth 1 point)Study the Mid-Atlantic Ridge. Its lighter blue color shading indicates the ridge is generally _____ compared to the surrounding ocean bottom away from the ridge. However, along the center of the ridge is a nearly continuous dark line representing a deep, narrow central rift valley that forms above tectonic plates that are separating. Seen in the view are other dark lines, aligned nearly perpendicular to the ridge and rift valley, but generally parallel to each other. These ocean valleys are associated with fracture zones (now inactive) related to differences in spreading rates. A.shallowerB.deeperAnswer Key: A Question 5 of 15 (worth 1 point)Mid-ocean ridges are underwater volcanic mountain ranges formed at diverging tectonic plate boundaries. Geologic evidence indicates that the landmasses on either side of the Atlantic Ocean were once joined together as one super continent, know as Pangaea. The Atlantic Ocean basin was formed when Pangaea split apart. The volcanically active Mid-Atlantic Ridge is marked in Figure 2 with red arrows denoting motion that identify it as a_____ plate boundary. Question 6 of 15 (worth 1 point)
Oceaan trenches are deep, elongated depressions on the ocean floor formed along convergent plate boundaries where the edge of one crustal plate has beenforced under the edge of another plate (the process known as subduction). According to Figure 2, a plate boundary extends along the west coast of South America. Return to the enlarged NGDC map where you had been viewing the Mid-Atlantic Ocean Ridge, and use the horizontal and vertical sliders to center the map view on South America's west coast.
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- Spring '08
- Plate Tectonics, west coast, Mid-Atlantic Ridge, plate boundaries