Figure: Bedrock Topography of Manhattan.
This figure shows the bedrock depths relative to sea level. The blue parts are where the bedrock is below the sea level and the orange parts where it is above. The deepest bedrock is in the Lower East Side (but that’s not why there are no skyscrapers there). Most of Manhattan island’s bedrock is some form of schist, though marble makes up part of northern Manhattan and East Harlem. Today most skyscrapers rest directly on the bedrock giving them a firm foundation. Click here to see a helicopter tour.
Source: Jason Barr, Dimitris Ntarlagiannis, and Jan Olchowski