Joppa Flats EarthCache
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These coordinates bring you to a vast tidal mud flat that is BETTER VIEWED AT LOW TIDE!
Go to http://www.boatma.com/tides/North-Shore.html for current tide charts.
Visit my Earthcache "Merrimack Tidal Marsh - GC2CXME" to see one of the best tidal marshes in MA.
Visit my nearby Earthcache "The Newbury Marsh - GC3335C" to view the largest salt marsh in New England.
Congratulations to Pelicansarepelican for being the first to log and submit answers!!
Joppa Flats is a classic example of a coastal wetland mud flat covering approximately 250 acres located within the intertidal zone of a river's estuary. Intertidal means the area is submerged and exposed twice a day with the change in tides. An estuary is a place where the ocean and river, land and water meet (in this case where the Merrimack River meets the Atlantic Ocean).
Glacial debris reworked and mixed by water was deposited in this area (where there is little wave action) after the last glacier retreated 15-18,000 years ago. Today a similar process continues as water flowing down river brings with it small particles of clay, silt and sand while rising waters bring sand up the river with each incoming tide. The result of all this is the mud you see here at low tide. Bay Mud is made up of Inorganic mud (tiny bits of sand, silt and clay) and Organic mud (decaying vegetation and animals). Bay mud has many unique characteristics, it is often saturated with moving water creating extremely fine-grain sand particles and it has a high concentration of clay, mostly from the silty river deposits, that results in a very soft, flexible and slippery mud. Layers of mud are classified according to their age. The Quaternary older bay mud layer from the Ice Age is abbreviated QoBM - "o" for older. Quaternary younger bay mud is abbreviated QyBM - "y" for younger. Other names for this mud include muck, sludge, mire, slush or ooze.
During low tide you can observe several distinct areas that comprise what is sometimes call the Barren Zone:
1.) The lowest point in the mud flats provides a channel for the river even during lowest tide. The mighty Merrimack may be reduced to a trickle of its self!
2.) As the tide comes in the water becomes gradually deeper and nears the shoreline. Sometimes you can see small sandbars because of the varying heights of the underlying mud. As the tide goes out you can see patterns in the mud made by the receding water as it rushes to the ocean.
3.) Closest to the shore you can see tufts or mounds of mud with grasses growing most of the year. The build-up of the mud makes it dense enough to support these plants that are tolerant of the salt in the water.
Wading birds are a good indication of the depth of the water at different points or if you are lucky enough you may see someone digging for clams. The mouth of the Merrimack River has severe tidal action considered by the US Coast Guard to be one of the most dangerous in the country. The rushing tides combined with the narrow opening at the Atlantic and the nearby barrier island called Plum Island are not to be taken lightly. It is not necessary to walk down the ramp and not advised because it can be very slippery.
Mudflats are intimately linked with salt marshes as they are both connected to the twice daily tides. Mudflats, like salt marshes, dissipate wave energy thus reducing the risk of erosion, damage to coastlines and flooding of low-lying areas.
In the early 1900's this area was called Flatiron Point and was home to the local clamming community, many lived in clam shacks or shanties. The Merrimack River became one of the ten most polluted rivers in the country as large mills up-river poured industrial waste into the Merrimack and raw sewage and other pollutants contaminated the ecosystem far downstream. Clean-up efforts began in the 1990's when environmental regulations promoted recovery of water quality and species population. In 2013 Joppa Flats was re-opened for the commercial harvest of soft shelled clams called "steamers". It takes about 30 clams or 2 hours of back-breaking digging then shucking (removing the meat from the shell) to make a pot of clam chowder. Try to imagine the hours of hard labor it took around 1911 when there were anywhere from 1 to 5 tons of shucked clams shipped daily to Boston from the surrounding communities!
Joppa Flats was named after an ancient city in Israel that was called a "site of miracles". For the millions of migrating birds on the Atlantic Flyway this area is surely a miracle. Because the mud consists of dacayed organic matter at the lowest depths and microscopic living creatures at the upper limits it provides nourishment and energy for the birds. Because the mud is like quicksand and very slippery predators are unable to track across the mud thus providing a safe haven for birds and waterfowl to feed on gem clams, clam worms, mud snails and ribbed mussels to name a few.
Maintaining mudflats helps protect the coast from erosion, but rising sea levels, dredging, development and pollution are constant threats.
TO CLAIM THIS EARTHCACHE YOU MUST SUBMIT ANSWERS TO THE CACHE OWNER BY CLICKING ON THE NAME "ROADWANDERER" OR USING THE GEOCACHING MESSAGE SYSTEM:
1. Do you think the tide at the time of your visit was high, low or somewhere in between?
2. How many distinct areas of the Barren Zone were you able to observe during your visit and how were they different?
3. Was there mud visible and if so describe any patterns you saw in the mud. What do you think caused these patterns?
4. Would you classify the bay mud you see as QoBM or QyBM and why?
OPTIONAL: Did you see any birds or other animals on the flats or in the water?
A picture is always appreciated (but not required) to show others the changes in different seasons and weather conditions.
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