As the Wisconsin Glacier advanced, Glacial Lake Passaic formed eventually rising until it found an outlet at Moggy Hollow, draining to the Raritan River.

[1] The Wisconsin glacier expanded and closed off lower height gaps to the north, forming Lake Passaic.

[4] Even as the glacier retreated, Moggy Hollow remained the main outlet due to debris left at Millburn until Little Falls and Paterson emerged from the ice.

[4] There were several post glacial lakes which formed above Moggy Hollow, bringing the ledge to its current height.

Visitors can either ask to cross the Buck Garden to reach the lower portion of the ravine, or park above on Liberty Corner Road to access the top of the ledge.