2. Morningside Heights is built atop Manhattan schist millions of years old
Manhattan schist, which can be found in Morningside Park, as well as nearby Marcus Garvey Memorial Park, is a type of very strong rock that was formed about 450 million years ago. Manhattan schist is the second-oldest bedrock in New York City after Fordham gneiss, which was formed around 1.1 billion years ago during the pre-Cambrian era. For reference, Manhattan schist was formed when all the continents were a single supercontinent called Pangaea. Although Manhattan schist is very stable, it’s found quite deep underneath lower Manhattan, from about 20 feet below Times Square to 260 feet below Greenwich Village.
A cliff made of Manhattan schist separates the top of the park in Morningside Heights from the bottom in West Harlem. In addition to rock outcroppings, there is a glacial groove at 121st Street, a scratch cut into the bedrock by glacial abrasion. But perhaps one of the most notable places to find Manhattan schist in Morningside Heights is Rat Rock, a giant boulder sandwiched between two apartment buildings on 114th Street. The boulder of Manhattan schist is 30 feet high by 100 feet long and is surrounded by a fence to prevent vandalism.