By Marcia Anderson
(Part two of a three-part series on the Palisades.)
Gazing to the west from Manhattan across the Hudson River we are greeted by the majestic Palisades. These cliffs are a 40 mile long geologic sill from Jersey City to Nyack, NY and, at points, several miles wide. The Palisades are 300 feet high at Weehawken, NJ and 540 feet high near Nyack. This mountain has both a significant role in the course of American history and a dynamic geologic history.
The Palisades were first described by Giovanni da Verrazano in 1541 as ‘looking like fence stakes’ along the river.
Why do the Palisades rock columns look like fence stakes? And how did they form? Natural cooling and contraction of basaltic magma creates the cracks and fissures found in diabase basalt. Basalt is one type of magma that has been extruded onto the surface as lava. Diabase is an intrusive rock formed by an identical magma to basalt; however, it cools at some depth in the Earth’s crust. When water collects in the rocks and freezes, it expands, exerting tremendous pressure on the rock (2000lbs/in2). Yearly cycles of freezing and thawing, weather and weaken the rock, creating enlarged cracks and sometimes late spring landslides.
On a rainy November night, in 1776, the invasion of the Red Coats into New Jersey began. Dozens of boats, covered by British warships, landed on a stone jetty in the Hudson River, just below the Palisades. British regulars, officers and German mercenaries disembarked and climbed the road up the Palisades sill. By 10 a.m., on Nov. 21, 1776, drums sounded and 5,000 men, led by Lt. General Lord Charles, Earl of Cornwallis, began to march south to take Fort Lee, the American rebel stronghold. The Cornwallis assault sent George Washington’s Continental Army into panic and they desperately retreated across NJ, all the way to Delaware. General Washington and his troops re-grouped over the harsh winter to later defeat Cornwallis …and the rest is history.
During the 1800s, millions of cubic yards of Palisades basalt and diabase were extracted at the Englewood Cliffs quarry for railroad ballast and aggregate that helped to build New York City. A sandstone layer was also mined and used to construct many of the famous New York brownstone buildings.
We can thank the NJ State Federation of Women’s Clubs for helping to protect the Palisades from total destruction by mining interests. Land was donated by the widow of E.H. Harriman (President of Union Pacific Railroad) followed by donations from George Perkins, John D. Rockefeller and J. Pierpont Morgan. This, along with state and federal monies was used to build Henry Hudson Drive and the Palisades Interstate Parkway (1947).
By 1930, the George Washington Bridge was built, enabling New Yorkers to walk, bike, drive, or take a bus ride from Manhattan to the Palisades. Enjoy a hike on any one of the numerous trails and historic sites located within the Palisades. The Fort Lee Historic Park Visitor Center, an 18th century soldier hut and campsite, is a great place to start. (http://www.njpalisades.org )
About the Author: Marcia is the bed bug and vector management specialist for the Pesticides Program in Edison. She has a BS in Biology from Monmouth, second degree in Environmental Design-Landscape Architecture from Rutgers, Masters in Instruction and Curriculum from Kean, and is a PhD in Environmental Management candidate from Montclair – specializing in Integrated Pest Management and Environmental Communications. Prior to EPA, and concurrently, she has been a professor of Earth and Environmental Studies, Geology and Oceanography at Kean University for 14 years.