The way the large composite silt is deposited in the Delaware river delta around Philadelphia could have only happened in a single cataclysmic event. The size and distribution of the rocks in the various layers show it clearly.
It isn’t studied by many and the continual erosion theory seems to dominate. Probably because it is the most prevalent effect over the past 500 million years of geological formation it the Appalachian ridges and the gap. But all the evidence is there for the catastrophic breach 3 million years ago.
And I was there when it happened