Similarly, the piles of debris left by the glaciers were encrusted over time into a single solid mass. Finally, during a period where the climate was extremely wet, a powerful river formed in the valley. It cut a channel through the lower, least encrusted layers of debris, which gradually eroded into the large opening of the arch.
Similarly, the piles of glacial debris were covered by sediment and eventually eroded into a single solid mass. A period of intense rainfall led to the formation of a powerful river that cut through the lower, least encrusted layers of debris, gradually forming the large opening of the arch.