Geomorphology of the Highlands
Jesse Fried • Jun 14, 2017
The NJ Highlands are the real bowels of the earth, brought from the firey depth to the surface through a billion eventful years. The formation of its resilient bedrock is such a long story, featuring so many earth processes such differnt points in the planet’s development, that geologists admit to being overwhelmed. A USGS authority concludes that “faults and bedrock structures in the Highlands region have exceedingly complex histories that are challenging to discern” . When the Highlands bedrock was first dredged back up to the surface, it probably was a big mountain rainge, but hundreds of millions of years of erosion have since worn it down.
To shorten this lengthy story, the Highlands are a swath of very old, very hard rock that now shares the daylight of contemprary New Jersey with younger, comparatively simpler rocks on either side. The region is no longer especially mountainous, but its elevation and ruggedness today is due its resistance to erosion compared with its softer neighbors. Its average elevation increases gradually as you go north.
Glaciers! One time, it was cold out, and glaciers like those you might find today in the Arctic stretched across the northern half or North America, as far south as NJ. Actually, this tends to happen whenever it's cold out for a period of thousands of years. The most recent glaciers to cover the continent, which Geologists named after Wisconsin, decided to pick somewhere right near I-80's route across the Highlands as the place to stop and advance no further. These are moving sheets of icen thousands of feet thick, which have huge effects on the landscapes they cross: sculpting hills and mountains, filling in valleys with debris, and scraping away the soil from prett much everywhere. As a result, the southern and northern halves of the Highlands look very different, and have had very different human histories. See the page on the land use history of the Highlands for details.
The Northern highlands are now classic NJ hiking country, with exposed bedrock ledges on glacially scoured hilltops providing nice views. Soils tend to be thin and rocky.
The Southern highlands contains some fertile valleys with limestone and dolomite interspersed with wide ridges of classic Highlands bedrock.
 Geology of National Parks, 3D and Photographic Tours: Highlands Sites in New Jersey. http://3dparks.wr.usgs.gov/nyc/highlands/ramapo.htm