Because skyscrapers tend to be built19 where hard rock is close to the surface, the shape of the Manhattan skyline can be read as a translation of the underground presence of Manhattan schist. Like serpentinite, schist has a composition inseparable from its history: The reason it’s so hard is that it was compressed over three hundred million years ago under a mountain range with heights similar to those of the Himalayas today. That range formed when two landmasses collided in the formation of Pangaea.
