Communipaw Cove EarthCache
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Waypoint 8 of 10 on Going Coastal’s NY-NJ Harbor Estuary EarthCache Discovery Trail in
Liberty State Park, caches developed by Going Coastal, Inc. (www.goingcoastal.org) as a special project in affiliation with Groundspeak and support from the NY-NJ Harbor Estuary Program and the New England Interstate Water Pollution Control Commission.
The NY-NJ Harbor Estuary Earthcache Discovery Trail is meant to help visitors develop a better understanding of the Estuary, make connections between earth and environmental science, and foster stewardship.
The cache is at the waysign map at the edge of Overlook Field. Geological forces shaped this landscape long before human impact on the environment. (visit link) The ground here is all made-land. There is no natural landscape. The railroads created this wide expanse of land now known as Liberty State Park from 1860 to 1928, filling in marshland and intertidal flats.
The Hackensack tribe of the Lenape natives used the area as a summer encampment called Communipaw, which means big landing place at the side of a river. Communipaw Cove stretched from the area of what is now Morris Canal on the north to Caven Point on the south. Washington Irving refers to the early Dutch settlement here as "the egg from which the great city of New York was hatched.”
The shallow marshes and waters of Communipaw Cove were filled with debris material, New York City garbage, and ship ballast (heavy items placed in the hull to balance ships). The surrounding waters were dredged, the bottom of the marshes dug-up to make the water deep enough for boats to dock. In some areas canal boats were deliberately sunk as retaining walls to hold the “fill,” which came from dredged spoil (silt scooped from the bottom from deepening the waterway), and refuse. Eventually, railroad landfilling extended the ground from Morris Canal in the north to Black Tom Channel in the south.
Geological forces shaped this landscape long before the anthropogenic or human impact on the environment. The natural substrate at Liberty State Park is at least 30 feet below the surface, bedrock of Triassic-Jurassic sedimentary formation. The earth floor has many layers. The substrate, the underlying layer, was formed in prehistoric times by the collision of tectonic plates and glaciers sliding across the landscape. Liberty State Park is located at the south end of a glacial ridge formed by the debris of a glacier, called a moraine. It separates Newark Bay Basin from the lower Hudson Basin, along the eastern edge of the Piedmont Province (a physiographic classification with the larger Appalachian Highland group). During Jersey City’s formative years, about 10,000 years ago, glacial till and glacial melt water formed a marshy habitat. (visit link)
The natural substrate at Liberty State Park is at least 30-40 feet below the surface, bedrock of Triassic-Jurassic sedimentary formation. Dig twenty feet down and you will find the fragments of salt marsh, made of silt, clay mud, and oyster shells. Keep digging and you hit bedrock. The earth floor has many layers. The substrate, the underlying layer, was formed in prehistoric times by the collision of tectonic plates and glaciers sliding across the landscape. Liberty State Park is located at the south end of a glacial ridge formed by the debris of a glacier, called a moraine. It separates Newark Bay Basin from the lower Hudson Basin, along the eastern edge of the Piedmont Province (a physiographic classification with the larger Appalachian Highland group). During Jersey City’s formative years, about 10,000 years ago, glacial till and glacial melt water formed a marshy habitat.
Millions of years ago the deep Hudson River channel didn't exist, it was nothing more than a stream. A clue to what changed it can be found all over New Jersey and New York. The clue is boulders which are found out of place and that are different from the rocks, which surrounds them. Many of these boulders may contain deep grooves and some may be polished, which indicates a force strong enough to move these boulders over huge distances. The forces responsible are glaciers. Glaciers are huge ice sheets that forms when wintery conditions persist year round and snow accumulates on top of past snow events forming towering sheets of ice. They are not stagnant however, they move and when they do they grind their way across the landscape breaking off rock from formations and carrying them in their base. These rocks behave like abrasives and scratch grooves in other rock formation they flow over. When the glaciers retreat or melt, they leave these boulders behind where we see them today in Central Park and parts on New Jersey. Over millions of years these advances and retreat of the ice sheets changed the landscape.
The crescent gouges call chatter marks in rock formations more than a mile above sea level that surrounds Liberty Park indicate that the glacier was over a mile thick. The glacier that most likely formed the area of Liberty State Park, advanced SE from Canada, which is indicated when you compare the orientation or direction in space, of these grooves in upstate New York to the ones in Central park.
Before the glaciers the water of the Hudson had slowly eroded the landscape and formed a V-shaped
channel indicative of a river channel but after the glacier, the Hudson was craved into a deep U-shaped valley indicative to glacial activity. The sides and bottom of the stream channel was gouged out to what we see now today. It was the glaciers that made New York- New Jersey Harbor Estuary.
However when the glacier retreated it left an enormous amount of glacial debris behind which blocked the Hudson Narrows where the Verrazano-Narrows Bridge is today from the Atlantic Ocean. The ridge called a glacial moraine connected Long Island to Staten Island and forced the Hudson to deviate to the west and exiting in the Atlantic through the Raritan Bay. What broke the ridge is believed to be a flash flood. The source of this flash flood is believed be the waters from Lake Iroquois, a huge glacial lake formed next to Lake Ontario at the end of the ice age. The glacier itself dammed the lake but over time it melted and weakened, eventually causing a serve flash flood that flowed down the Hudson and broke through the moraine at the Verrazano Narrows.
In South Overlook Field the Liberation Monument by sculptor Nathan Rappaport stands twenty-foot statue tall. The statue commemorates the liberation of Holocaust victims with its depiction of a WWII concentration camp survivor being carried to freedom by an unarmed American soldier.
Today, the ground here is all man-made. There is no natural landscape. The physical alteration began with the railroads that created this wide expanse of land now known as Liberty State Park from 1880 to 1916, filling in marshland and intertidal flats. The shallow marshes and waters of Communipaw Cove were filled with debris material, New York City garbage, and ship ballast (heavy items placed in the hull to balance ships).
Logging Activities:
1. You are currently in an area where glaciers had once been. Observe the area and state all the clues of glacial activity.
2. When the glacier advanced from the north into this area it grind along the land surface and eroded the land.
3. Looking over Hudson Bay into Manhattan explain why both the bay and Manhattan were not evenly eroded to the same depth.
Data Sources:
• Geologic Map of New Jersey (visit link)
• Liberty State Park (visit link)
Name and Type of Land
Liberty State Park
200 Morris Pesin Drive, Jersey City, NJ 07305
Phone: (201) 915-3440
(visit link)
OWNER: NJ Department of Environmental Protection
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