400 Feet of Sea Level Rise Since the Ice Age

When you stand on the beach at Atlantic City today, you're looking at a coastline that didn't exist 12,000 years ago. The shoreline was miles offshore, out on the continental shelf where water depths now reach 400 feet or more. Sea level was that much lower. If you could have stood in that same spot back then, you would have been in the middle of a forest, buried under the ice sheet that extended 20, 30, maybe 40 miles beyond the present coast. The ice didn't stop at what we now call the shoreline. It kept going, out over land that is now underwater. As the great ice sheets melted and retreated, all that water had to go somewhere. Sea level rose 400 feet. Coastlines moved inland. Entire landscapes vanished beneath the ocean. This wasn't a gradual, uniform process. It happened in pulses, some of them catastrophically fast.