Editing Hunterdon County, New Jersey (section)

=== Geology ===
{{unreferenced section|date=June 2017}}Around 500 million years ago, a chain of volcanic islands shaped like an arch collided with proto North America and rode over the top of the North American plate. The rock from the islands created the highlands of Hunterdon County as there was a shallow sea where Hunterdon County is now located. Then around four hundred million years ago, a small continent that was long and thin, collided with proto North America. This collision created compression, which caused heat. The Paleozoic sediment of shale and sandstone folded and faulted. The heat allowed the igneous rock to bend, thus Hunterdon County was born.

The African plate which later collided with North America created more folding and faulting, especially in the southern Appalachians. Then the African and North America plates tore and drifted away from each other.

The Wisconsin glacier that entered into New Jersey around 21,000 [[Common Era|BCE]] and then melted around 13,000 BCE did not reach Hunterdon County. However, there are glacial outwash deposits from streams and rivers that flowed from the glacier southward depositing rock and sediment.

Hunterdon County has two geophysical provinces. The first is the Highlands which is the western section of the county. The other is the Piedmont which is the eastern and southern section of the county. The Highlands account for one-third of the area and Piedmont accounts for two-thirds of the county. The Highlands are part of the Reading Prong. Limestone and shale over igneous rock comprise the Highlands. Piedmont includes the Hunterdon Plateau and the Raritan Valley Lowlands which are {{convert|150|to|300|ft}} above sea level. Piedmont is made up of shale and sandstone.<ref>https://nj.gov/dep/njgs/enviroed/county-series/Hunterdon_County.pdf Geology of Hunterdon County In Brief</ref>