Birkrigg Common EarthCache
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A superb Limestone pavement situated on Birkrigg Common with great views across to the Lake District,Ulverston sands and out to Morecambe bay.
The pavement is an excellent example which typifies the type found in the area.
When you get to the published coordinates you will notice all around you in huge clumps,a grey stone floor protruding from the grassy banks of the hillside, but what is this strange phenomena ?
What you can see here and will indeed be standing on is known as a Limestone Pavement, Limestone pavements are a scarce and non-renewable resource, they are found in the UK in the Yorkshire Dales, some parts of Cumbria, and smaller areas in Lancashire, Wales and Scotland, They were exposed by the scouring action of ice sheets during the ice age. Since then the rain water movement has widened the cracks in the pavements to form a complex pattern of crevices known as GRIKES between which are massive blocks of worn limestone which are known as CLINTS, both of which can clearly be seen here.
Limestone is a rock composed mainly of calcium carbonate CaCO3. Limestones comprise a large variety of rocks including carbonate muds and oozes, chalks, ooliths and bioclastic limestone. They form in a variety of environments from deep sea (but above the carbonate compensation depth), temperate seas, tropical sea, lakes and rivers. Most caves are found in limestones due to erosion by acidic water, which is exactly what forms the Grikes and unusual shapes you see here today, the ater would have dissolved and slight surface hollows over time, the grikes get wider over time as the water works it's way down dissolving the calcium carbonate as it passes, ironically these grikes are perfect places for plantlife to grow, these plants secrete acid through their roots which in turn passes into the water and can add to limestone corrosion, some grikes can be up to 2 meters in depth.
In this area the Limestone pavements are classified as 'Carboniferous limestone pavement', this is due to the formation of the pavement falling within the 'Carboniferous period'.
The Carboniferous Period occurred from about 354 to 290 million years ago during the late Paleozoic Era. The term "Carboniferous" comes from England, in reference to the rich deposits of coal that occur there.
The Carboniferous period itself, falls within the emcompassing 'Paleozoic Era'-
543 to 248 Million Years Ago.
If you carry on a little further after the pavements you will come to the well maintained trigpoint which has been adopted by the locals to commemorate the refurbishment of the parish hall, here at the trig there are also a lot of small sections of limestone pavement to be seen, along with even better 360 degree views.
A good place to start your walk is Bardsea village, you will walk uphill past several great existing caches and also an old stone circle still in situ.
There is ample parking at the National Trusts' 'Sea Wood' closeby, with easy to follow paths leading up Birkrigg Common.
To claim this Earthcache please Email me the following info:
1. What is the approx width/depth of the largest Grike near to where you are standing?
2.How many seperate periods periods make up the PALEOZOIC era and what are they?
3. Please post a photo in your log of yourself or your GPS standing on the Limestone pavement.
Please do not post the answers to the questions in your logs for obvious reasons :-)
PLEASE NOTE: I receive a very high number of Earthcache emails, I can’t reply to them all otherwise I’d be doing nothing else all day, as has always been the case there is no need to await a reply from me regarding your answers…. However due to numerous people thinking they can just log these caches without emailing any answers, and/or completing the required tasks these will be picked up, and the logs will be deleted without further communication. To facilitate this Please email your information either before, or AT THE SAME TIME OF LOGGING THE CACHE, Thanks.
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V'gf nyy nebhaq lbh !
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