Martin's Head Coastal Bluffs EarthCache
Martin's Head Coastal Bluffs
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A visit to Martin’s Head western beach shore might prompt you to ask what has caused the beautiful beach to form or why is the bluff still there when the bluff face is too unstable to support solid vegetation.
The posted coordinates will bring you to the eastern end one of the larger coastal bluffs found along the Fundy coastline. This beach has a coastal bluffs formed of ice contact drift from the most recent glacial event. A bluff is defined as a steep shoreline slope formed in sediment (loose material such as clay, sand, and gravel) that has three feet or more of vertical elevation just above the high tide line. Cliffs or slopes in bedrock (ledge) surfaces are not bluffs and are not subject to significant erosion in a century or more. Beaches and dunes do not form bluffs, except along the seaward dune edge as a result of erosion.
The story of this coastal bluff begins with the last glacial retreat. During this retreat the melting of the ice sheet released more water and gravel then is possible to imagine. Even as the ice margin withdrew, internal flow within the glacier continued to transport its sediment load southward toward the edge of the vast ice sheet. Large quantities of sediment were dumped into the ocean at the edge of the melting ice sheet, and these deposits are now exposed to view because the land rose above sea level. Remnants of the glacial sand and gravel are to be found here under the high banks located along this shore.
This coastal environment is dynamic and subject to continuous change. Gravitational processes of creep (slowest movement that operates every day, everywhere, no matter how gentle the slope), slumping (most commonly after heavy rains saturate the ground) and occasional land-sliding (fastest movement) modify the shape of coastal bluffs. Rising sea level along Fundy's coast allows storms and coastal flooding to reach further inland and erode sediments at the base of bluffs. Steepening of bluffs by erosion at their base may lead to increased slumping and deposition of clay, sand, or gravel in the intertidal zone which then acts to stabilize the bluff for a period of several years to decades as coastal processes rework and remove the slumped material. Once the material at the base of the bluff is removed entirely, the bluff may then be undercut again and the cycle of slumping followed by protection of the bluff base will be repeated. Most bluffs erode erratically; perhaps losing ground one year and not the next. Over a period of many years a bluff may permanently retreat landward. Historical analysis can help determine the average rate of bluff retreat.
This bluff is a highly unstable bluff with a limited vegetated bluff face and a beach shoreline. The bluff face is too unstable to support stable vegetation and the few tree on the face have come down from above. These bluffs are constantly being eroded by waves to create this mixed sand and gravel beach in front the bluff and are subjected to movement by the sea.
At the posted coordinates you will find yourself viewing the bluff where you should be able to see the layering of the sands and gravels making up the bluffs and the boulders on the beach that have not washed away. You should be able to see evidence of trees that have been under cut by the water. The bluffs that you are looking at are the remains of the Ice Contact Drift that is slowly falling into the ocean. Remember this is an earthcache so there is no container just an earth science lesson at an amazing natural feature that needs to be protected. To log this cache, email me through my profile the height of the bluff above the beach and what you can see for evidence of the bluffs instability. Please include the name of the earthcache and the number of people in your group in your email. In your log please take the time to describe what you find special about this beach and its bluffs, it is also nice to include photo so other have some idea what to expect.
Additional Hints
(Decrypt)
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