All over the Catskills you can find ancient shells, clam-like fossils and other marine life partially buried in the sandstone because, during the Devonian period, the Catskills were at the bottom of the sea, somewhere around the Bahamas. The Devonian Period was 400 million years ago and since then the Americas have moved farther north to the position they are in today. On hikes to places like Slide, Giant Ledge and Panther Mountain, the rocks look like they had pebbles thrown at them while they were molten. According to Catskill Mountaineer, Panther Mountain sits on top of a meteorite hit that happened 375 million years ago. In the middle of the picture above, taken on Slide Mountain, you will see what looks like the remnants of a curling shell.