Paterson, New Jersey Topography
In this topographical map of the Paterson, New Jersey area you can see the two ridges, First and Second Watchung Mountains. These are two ridges of basalt, a rock that is highly resistant to weathering.

You will notice that the contour lines are much closer together on the southeast side of Second Watchung Mountain versus the northwest side of the mountain. The basalt is a layer dipping or tilted down toward the northwest. The southeast side being a cliff in many places.

These layers of basalt were formed by the solidification of several different lava flows about 190 million years ago, as the rift between North America and Africa was opening.