Life's a Beach #55 - Holland-on-Sea EarthCache
Life's a Beach #55 - Holland-on-Sea
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The Life's a Beach series, started by Heartradio in Beer, Devon, and growing rapidly, comes to Essex for the first time at Clacton-on-Sea and Holland-on-Sea!
This is a sandy beach which stretches for 5km and has recently been installed with sea defences.
Coastal erosion is "the wearing away of land and the removal of beach or dune sediments by wave action, tidal currents, wave currents, drainage or high winds".* Strong tidal conditions both deposit and remove sand and other materials (rocks, shells, and unfortunately litter) from the beach. Longshore Drift is the process by which materials such as sand/sediment are transported by waves which approach the beach at angles due to prevailing wind, in a zig-zag motion. The swash is the movement of water onto the beach when the wave break. This deposits any material being carried in the water onto the beach. The backwash is when the wave then retreats backwards back into the sea. This removes material from the beach back into the sea. As backwash occurs at a greater angle than swash, it means that it generally is more effective.
Over time, more material is eroded than replaced, so unprotected land is also taken by the sea by cliff collapse, when the erosive power of waves act on unprotected cliffs. This can occur by hydraulic action, whereby the sheer force of water is enough to erode cliffs, abrasion, whereby hard rocks carried in the sea scrape and break chunks off the cliff, or solution, whereby the slightly acidic nature of seawater is enough to erode some rock types in the cliff, such as chalk.
Sea defences attempt to slow down land erosion by the sea. Groynes are one example of a sea defence; they are man-made barriers placed along a beach to block the process of longshore drift.
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1) At GZ is a rock with a plaque outlining the coastal regeneration scheme.
a) How many homes and businesses are protected from coastal erosion because of these groynes?
b) How many new beaches have been created due to the works?
Now look over the beach and answer these questions:
2) What are the groynes made of and what shape are they? Suggest one reason each for why the material and shape were chosen.
3) What evidence is there that the beach is still being eroded despite the groynes?
4) Take a look around you at HINT waypoint. What is here that provides evidence that material is still being deposited despite the groynes?
5) Have a feel of the sand. Why do you think it is so susceptible to erosion by the waves?
Taking photos is encouraged, but not compulsory. Pictures that reveal the answers risk being deleted.
*Taken from Wikipedia: Coastal erosion
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