Birnbeck EarthCache
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Many locals will know that the Birnbeck area of Weston has its own island and pier. But what less people know, is that it has its own rock type too...
This Earthcache highlights Birnbeck Limestone found in this area, particularly in the formation of Birnbeck Island.
Birnbeck Island and Pier
Birneck Island is a small rocky island just off the coast, north of Weston-super-Mare. In 1867, a pier was built; the only pier in the UK to connect an island to the mainland (which is still true today). It experienced lots of tourism but eventually declined after other attractions were built in the centre of Weston. It closed in 1994 and has been reduced to ruin ever since due to the unforgiving power of the tides in the Severn Estuary and lack of maintenance.
Birnbeck Limestone Formation
Birnbeck Island and some of the surrounding areas (including Middle Hope and some parts of Kewstoke) are made of a particular type of limestone, which has been named as Birnbeck limestone as it is only found here.
Birnbeck Limestone is a combination of usual sedimentary limestone found in this area, but also combined with coarse-grained sediments from shells, dolomite, shale, mudstone, corals, skeletons of small organisms, and calcite minerals- these all ingrained into the limestone when it was forming and produced Birnbeck Limestone.
The combination of the above materials has made Birnbeck Limestone into a tough rock, able to withstand the most extreme of erosive powers from the waves. This has meant that Birnbeck Island has stayed relatively the same size for hundreds of years.
To claim a find on this Earthcache, you must answer the questions below in an email/message to me within 24 hours of logging a find. Any drastically wrong or incomplete answers or any logs from a cacher without sent answers risks their log being deleted. Any photos that reveal answers will also be deleted.
Go down the steps and you should see an outcrop of Birnbeck Limestone along the wall, as well as some further ones down the further set of steps (if the tide is out).
1) Describe the Birnbeck Limestone that you see here. What are the colour(s) and textures of the rock(s)?
2) What is causing a discolouration to the rock here that isn't causing a discolouration to the rocks on Birnbeck Island? Why do you think this is?
3) Estimate the width of Birnbeck Island and how far out to sea it is.
4) To prove you visited- at the top of the steps (GZ) there is a signpost.
a) Name the small body of water around Birnbeck Island (initials AH)
b) Name 2 factors that make the Severn Estuary 'unique in Britain and very rare worldwide'
DO NOT UNDER ANY CIRCUMSTANCES ATTEMPT TO ACCESS THE PIER/ISLAND. THE PIER IS DERELICT AND IT'S NOT ONLY DANGEROUS BUT ALSO ILLEGAL TO DO SO (TRESPASS). ALL QUESTIONS ARE ANSWERABLE WITHOUT ACCESSING THE PIER/ISLAND.
As part of the 13th International Earthcache Day (October 2015) I challenged myself to place an Earthcache every month until Earthcache day 2016, kicking it off with GC62T8F. This Earthcache is number 8 in that challenge (May 2016).
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