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 accumulated over time into a single solid mass. During a period of intense rainfall, a powerful river formed in the valley and cut a channel through the lower, least encrusted layers of debris. This erosion gradually created the large opening of the arch.