Living on the Edge: Beach Habitat EarthCache
Living on the Edge: Beach Habitat
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Waypoint 4 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 an edge habitat visible, though not accessible (locked gate) from the trail path. It is a typical transitional zone from sandy beach to small shrubs.
Beaches are natural geological formations that develop where a body of water meets the land. Beaches can be made of a variety of materials. As you can see this particular beach has both a sandy part and a rocky part. These rocks were placed here as rip rap for shore protection. The beach is constantly in motion, endlessly eroding and replenishing.
Sand itself is sediment made up of different types of rocks that were washed down rivers and ground up by the waves over hundreds of thousands of years. Rocky beaches are often caused by more recent natural erosion of the land and will become a sandy beach as time goes on. (visit link)
A complex marine ecosystem lives on the edge. A single grain of sand is home to bacteria, diatoms, and microscopic organisms. The littoral zone is the intertidal zone where land and sea meet, covered with water at high tide and exposed to the air during low tide. (visit link) The dry sand above the high water mark is called the backshore, where tides and waves will form a beach berm like a wave of sand capped with a crest. Just above the high tide line is the wrack line also called the strand. (visit link) Here you will often find a line of seaweed, debris and other detritus that was washed ashore by the incoming tide. Over time, this decomposing organic matter will trap sand and sediment to build sand dunes.
How can you tell if this beach is tidal or not? Look at the sand. Do you see a discoloration of the sand and rocks as the beach slopes down closer to the water? That is an indicator that this beach happens to be on a tidal waterway. Over the course of a day in the New York-New Jersey Harbor Estuary, the water will rise and fall twice. At low tide, the water will be about four feet lower than the water at high tide. This is called the tidal range. The tides are caused by a gravitational pull of the moon, and to a lesser degree the sun. The tides follow the phases of the moon, as the moon waxes and wanes, all the oceans in the world move with it! (visit link)
Notice the beach slopes; this slant is caused by sand being pushed up by wave action.
The beach is not very steep at the shoreline, which gives a clue that the water in the basin is shallow. The waves that hit the shoreline carry sand and small rocks, which build up the beach. This sediment transport and wave energy shapes the coastline. Beaches on tidal waters will become sandy faster than those with no tides.
Every six hours, the water line will start at the top of the beach (almost to the tree line) and will recede down the beach. Six hours later the water line will start to climb back up the beach until the water is back at the tree line six hours after low tide. This ebb and flow of the tides will continue on this beach forever and ever. It is easy to predict tides. The time between high and low tide is six hours apart and the tide cycle happens 50 minutes later each day.
The tide cycle here is unique to this beach. Because water is fluid and the moon is in constant motion the high tide here will happen at a different time than in other parts of the harbor. During the spring tide at new moon and full moon, the moon and sun are aligned pulling together and tides are at their highest. During neap tide at the first and third quarter phases of the moon, the moon and sun are at a right angle pulling in different directions and the tides reach minimal height.
When wind and water meet the result is a wave. If the wind is strong, the waves can become choppy. Are the waves here big or small? For the most part these waves are small. Why do you think that is? Waves are formed hundreds of miles out at sea and become bigger and bigger from the wind pushing on them as the wave gets closer to the land and crashes on the slope of the beach. You would think these waves would be huge! The reason these waves are small is because both the Brooklyn and Staten Island coastline protects New York Harbor where most of the big waves lose their momentum as they enter the Upper Bay.
Logging Activities:
1. At the time of your visit, what is the tidal flow? Provide date and time of visit.
2. The color and texture of the sand can tell you what rocks and sediment the sand is made from. What is the color and surface texture of the beach sand? Try to guess what type of local rock this sand may have come from.
3. (Optional) From the pathway, view the wrack line and identify one item stranded on the beach by the tide.
To log a find on this earthcache, email the cache owner (DO NOT POST IN YOUR LOG), unless instructed otherwise. Use your GPS device to locate the next cache -GC2T1JQ. (visit link)
Remember, to upload a photo and let us know in your log ways we can improve the trail.
To reserve a field trip for your class, please contact the educators at the Nature Interpretive Center at (201) 915-3409. Geomate Jr. GPS units will be provided for your group for your high-tech exploration of the geology and ecology of Liberty State Park. Additional resources are available online at www.goingcoastal.org (visit link)
Data Sources:
• Beaches - (visit link)
• Going Coastal New York City by Barbara La Rocco (Fordham University Press 2009)
• Littoral Zone - (visit link)
• Tides and Currents - (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
Additional Hints
(No hints available.)