All good things must end, and our tour is coming to a close! But there is still one stop left, and we're heading to the middle of the Atlantic Ocean and Ascension Island! Ascension Island is around 60 miles from the Mid-Atlantic Ridge, in between South America and Africa, and is located at 7°56'24.21"S 14°20'59.91"W. These divergent boundaries is a boundary between two plates that are spreading apart. Most divergent boundaries lie along the ocean floor, and contain rift valleys, which are deep valleys in the middle of a mid-ocean ridge. Below a rift valley, molten rock is forced upwards through cracks/rifts along the valley. When the molten rock cools, it hardens into new oceanic crust. The older oceanic crust on both sides of the rift valley moves away from ridge. This process is sometimes called sea-floor spreading. Rift valleys are typically broken into segments that are separated by fracture zones. These fracture zones run perpendicular to the mid-ocean ridge, and have been found to be a source of the earthquake activity occurring along mid-ocean ridges. If you look at a map that observes elevation, earthquake activity, volcanic activity, and the age of rocks, you should be able to notice that new rocks, earthquake activity, volcanic activity, and shallow elevation all line up. Coincidence? I think not!
That concludes this final blog post and I hope you have enjoyed this once in a lifetime tectonic plate tour!
-KY
the images you picked out pair with your explanations were great. I totally got everything you said. good job. EF
ReplyDelete