And one of the things he had observed is that if you look at mountains like the Appalachians, you often find that the rocks in them are folded, and they're folded in a particular way, which suggested to him that they were actually being compressed from the side.
Una de las cosas que observó es que si ves las montañas como los Montes Apalaches a menudo consigues rocas con pliegues. Los pliegues son muy particulares lo que sugerían que fueron comprimidas por los lados.