Pictures from the edge To see an animated version of this map, click here . It's a violent world at the edges of our continental shelves, which could serve as a geology textbook Plate tectonics, dissolving rock, salt gushers and plain old erosion give widely different forms to the slopes where our continent meets the ocean floor. The images on these pages provide our clearest pictures yet of what is happening where. Features as small as an acre can be seen, a resolution 5,000 times that of similar images produced from satellite data. We are offshore, south of Baton Rouge, looking northeast toward Pensacola, Florida.
Craters form when salt resists compression, mushrooms upward and collapses.
Salt also makes the sediment edges bulge. When the United States in 1983 extended its territorial waters out to 200 miles, surveys were ordered. The images have been distorted by making the vertical dimension four times as high as it should be to show geological features more clearly. Black areas are those for which no data are available. By John P. Wiley jr.