Shorakkopoch Rock’s Erratic Past EarthCache
Shorakkopoch Rock’s Erratic Past
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Waypoint 5 of 10 on Going Coastal’s NY-NJ Harbor Estuary Earthcache Discovery Trail in Inwood Hill 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.
Follow the walkway southwest to the edge of the open field at the base of the wooded hill. You are walking on the original shore of Spuyten Duyvil Creek. The creek was once surrounded by 15 acres of wetlands. The creek now lays further back because portions of the old waterway and salt marsh were replaced by landfill from construction projects.
The hydrology or water flow of Spuyten Duyvil Creek was rerouted by dredging, straightening and filling making the earlier winding creek a navigable channel linking the Hudson River with the Harlem River. This field was filled in the 1930s by Robert Moses in his transformation of the parkland.
People changed the topography in order to make the park more level for a playing field (imagine playing football on such a steep slope!). In engineering, when material is removed from the ground it is called “cut” and when material is added to the ground it is called “fill”. Cutting and filling happens all the time, and you have probably seen it if you have ever passed by a construction site. The area you are in has other major examples of cut and fill.
Shorakkpopoch Rock is a glacial erratic of Palisades Diabase transported to Inwood Hill by glaciers that pushed everything in their path like a snowplow and pulled soil and boulders beneath it, dropping them as the ice melted and the glacier retreated. It is called erratic, because it was formed miles away in western Connecticut before being picked up by the glacier and deposited on the shores of Spuyten Duyvil. (visit link)
If you look closely you can see hairline cracks in the rock. When the temperature changes heating or cooling the rock it will expand or contract causing weathering, like cracks. If water gets into the crack and freezes into ice, it will expand and make the crack in the rock even bigger.
This rock is known as Shorakkopoch Rock, named for the large Lenape (Delaware tribe) settlement on its banks. Shorakkopoch is the native word that described the landscape. It means “the wading place,” “the sitting down place” or “between the ridges.” Henry Hudson sailed the Half Moon into this inlet in 1609. On this spot there once stood a giant 280-year-old tulip tree, 165 feet high and a girth of 20 feet around - thought to be Manhattan's oldest tree. Unfortunately, the tree fell in a storm in 1938.
O Tulip Tree! O Tulip Tree!
What changes time hath wrought!
What scenes have passed beneath thy bough!
What fleeting age hath brought!
-Augustus Post June 3rd, 1933
(visit link)
Shorakkopoch Rock has a plaque that commemorates the site of the tulip tree where legend has it Peter Minuit, the leader of the Dutch colony of New Amsterdam, bought Manhattan from the Lenape tribe in 1626 in exchange for 24 dollars worth of beads. The tulip tree was a witness to how humans transformed this landscape.
Turn so you are facing Spuyten Duyvil Creek, and take a look at the landscape. Compare your view to the ancient shoreline, still evident in the landscape. You can really imagine from this vantage point how drastically the topography has changed.
In the adjacent hills, you may still find evidence of shell middens, the garbage heaps of many oyster dinners and, perhaps, a wampum station, making bead necklaces valued by the “Indians” in trade. Colonists later mined the composting oyster shells made up of calcium carbonate (lime) for fertilizer and mortar. (visit link)
Natural oyster beds once covered the wetlands of Spuyten Duyvil Creek and the Harlem – Hudson River confluence. In fact, oystering continued here until dredging of the Harlem Ship Canal took away the oyster beds and wetlands in 1889. Oysters are filter feeders that live for up to 30 years. This means that pump water through their gills to feed. As oysters feed, they help keep the water clean, removing contaminants. One oyster can filter about 50 gallons of water a day.
Logging Task:
1. How has cutting and filling affected this landscape?
2. Which landforms visible here are created by nature and which are caused of human activity?
3. There is a plaque on Shorrakkopoch Rock commemorating the purchase of Manhattan Island at this spot. How many guilders did the Peter Minuet pay the Native Americans for Manhattan? (See plaque).
4. (Optional) How many gallons of water will an oyster filter in its lifetime?
To log a find on this earthcache, email the cache owner (DO NOT POST IN YOUR LOG). Use your GPS device to locate the next cache - GC2RWJR. (visit link)
Remember, to upload a photo and let us know in your log ways we can improve the trail.
Data Sources:
• Sidney Horenstein geologist, American Museum of Natural History
• Mark Kurlansky The Big Oyster Ballantine Books, 2006
• Shorakkopoch Rock (visit link)
• Viele’s Water Map of 1874
• Wikipedia: Middens, Peter Minuit, Oyster
Data Collected: September 26 – March 11, 2011
Name and Type of Land
Inwood Hill Park
W 218 Street & Seaman Avenue, Manhattan
Phone: (212) 304-2365
www.nycgovparks.org
Additional Hints
(No hints available.)