Discover why schist, a type of rock that underlies New York City's Manhattan borough, allows skyscrapers to soar, and learn why it’s present along the entire East Coast, in this video from NOVA: Making North America: Origins. Schist is composed largely of platy crystals. It is tough and solid enough to support the foundations of tall buildings. It starts out as mud that hardens under intense heat and pressure. The Manhattan schist layer comes near the surface in midtown and downtown, making these locations ideal for builders looking to attach skyscraper foundations firmly into bedrock. This resource is part of the NOVA: Making North America Collection.