Hudson River on the Rocks EarthCache
Hudson River on the Rocks
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Waypoint 10 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.
This cache is a vista above the Hudson River. The river delineates two distinct geological events that formed the rock under your feet and the magnificent Palisades across the water gap. The rock pinnacle of the overlook dates 500 million years ago taking form at the buildup of the super-continent made up of called Pangaea, (visit link) formed when the continents on earth collided during the Paleozoic Era. It is Manhattan schist of the metamorphic variety of sedimentary rock.
Across the river, the vertical cliffs of the Palisades formed 200 million years ago in the early Jurassic Era during the Pangaea rift – when a tear in the earth’s crust began to open the Atlantic Ocean and deconstruct the super continent. (visit link) The Palisades are made of igneous rock formed when hot, molten magma cooled beneath the earth’s crust and molded the distinct palisade-fence appearance. (visit link)
The Hudson River is the southernmost glacial fjord in the Northern Hemisphere. Fjords are defined as valleys eroded well below sea level by glaciers, and then filled by the sea after the glaciers retreat. The Hudson River is an arm of the sea for about half its length.
The land drained by a river is its watershed. The Hudson River watershed, a drainage area of 13,390 square miles, empties into Hudson River flows into the Harbor Estuary where it mixes and circulates with seawater from the Atlantic Ocean. The geology and soil types in the watershed determine the nutrients transported from the land by runoff and rivers.
A river’s source is the highest body of water feeding it. The source of the Hudson is 315-miles lies north in the Adirondacks named Lake Tear in the Clouds. (visit link)
The river is named after the English explorer Henry Hudson, who explored the watercourse while he was looking for a short cut route to Asia. The Lenape called the river Muhheakantuck, translated as “the river that flows both ways.” So, how can it flow two ways?
Being a tidal river, the Hudson has lower elevations than non-tidal rivers. Tidal river elevations are fairly close to sea level elevations. The Hudson River’s elevation is close to the sea level for over 100 miles in the north direction! This is why the Hudson River is under the influence of the ocean’s tides. The river changes direction based on the tidal current of the Atlantic Ocean. Twice a day sea levels rise and fall.
Imagine the ocean taking two giant breaths a day. When the ocean exhales it pushes ocean water out, and higher elevated areas get flooded with seawater. When the ocean can’t breathe out anymore it is called high tide. After high tide the ocean then inhales and sucks the seawater back in. When the ocean can’t breathe in anymore then it is called low tide. The ocean’s breathing goes on all the time, and it is caused by the moon’s gravitational pull and to a lesser degree the sun gravitational influence. When the Atlantic Ocean ‘inhales’ the river flows south into the NYC harbor toward the ocean. When the Atlantic Ocean ‘exhales’ the ocean pushes the river away from it, and the river flows upstream in the north direction!
Water in the Harbor Estuary is constantly changing. Heat initiates the cycle changing water from solid (ice) to liquid (water) to gas (vapor). When the heat is taken away, water turns to ice, then water vapor becomes liquid. The water from the estuary can turn into water vapor becoming rain that is taken up by the ground and rivers. The water that runs off into rivers, flows to the sea, eventually evaporates and starts the process over again. (visit link)
Events that occur far upstream impact the quality of water in the estuary. The drainage basin or watershed of the NY-NJ Harbor Estuary encompasses about 16,300 square miles, including much of eastern New York, northern New Jersey, and small parts of western Connecticut, Massachusetts, and Vermont. (visit link)
The quality of the Estuary’s waters is affected not only by activities occurring directly in the Harbor and the New York Bight but also by industrial, agricultural, land use, and other individual practices throughout this larger watershed. As rainwater moves over the land in the watershed, it carries with it many potential pollutants that eventually end up in the Estuary – oil dumped down storm drains, pesticides from farms, lawn fertilizers, oil and gasoline from highway runoff, sewage from failed septic tanks, and sediment from construction projects.
Logging Tasks:
1. Use the compass on the GPS to determine which direction the water flowing? Is the tide coming in (flooding) or going out (ebbing). Record the date and time. (POST TO LOG)
2. What are some reasons for the differences in salinity as one journeys down the Hudson River?
3. (Optional) What types of activity do you observe on the Hudson River? If there are vessels, can you name the types. (POST TO LOG)
4. (Optional) How do you use the NY-NJ Harbor Estuary? your personal oexperience and observation, how can you help preserve and conserve the Harbor Estuary? (POST TO LOG)
To log a find on this earthcache, email the cache owner (DO NOT POST IN YOUR LOG), unless otherwise instructed.
Thank you for exploring the NY-NJ Harbor Estuary EarthCache Discovery Trail at Inwood Hill Park. You might want to visit our trail at Liberty State Park, beginning at GC2RW4D. Please join us online at (visit link) or (visit link)
To reserve a field trip for your class, please contact the Urban Park Rangers at the Inwood Hill Park Nature Center. Geomate Jr. GPS units will be provided for your group for your high-tech exploration of the geology and ecology of Inwood Hill Park. Additional resources are available online at www.goingcoastal.org (visit link)
Data Sources:
• Going Coastal - (visit link)
• Hudson River Watershed: (visit link)
• NY-NJ Harbor Estuary Program: (visit link)
• The Hudson River: An Illustrated Guide to the Living River by Stephem P. Stanne
• The Hudson River Foundation - (visit link)
• Wikipedia: "Hudson River"
Data Collected: September 26 – April 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
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