2. Morningside Heights is built atop Manhattan schist millions of years old

rock stuck between two buildings on 114th Street

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.