To be fair, there is real geology behind the idea that erosion can happen fast in catastrophic food events.

From Wikipedia on the Bonneville Flood:

At the peak of the flood, approximately 33,000,000 cubic feet per second (930,000 m3/s) poured over the Snake River Plain at speeds of up to 70 miles per hour (110 km/h) and deposited hundreds of square miles of sediments eroded from upstream.[8]

Although the peak of the flood lasted a few weeks at most, erosion at Red Rock Pass continued for a few years before water ceased to spill over.