[Strategerist]

In many cases the Terminal Moraine of the glaciers is right next to the Watchungs, but the Watchungs themselves are volcanic basalts, so I'm really picking nits I guess.

[Question_Assumptions]

While you are correct, I thought the surface shape of the Watchung Mountains was because of the terminal moraine. Maybe I'm wrong. But, yes, the false rift (now filled with all sorts of clays and shales found throughout Central Jersey) that ended at the Atlantic Highlands started at the Watchung Mountains. I have a yard full of very nice shale but it's fossil-free thanks to the fact that the false rift was deposited in desert conditions.