I say unusual but there are plenty of other sites in the UK - just not many around here (or in the world as a whole as it happens).
History
Rising to 221 metres above sea level Little Doward is a fairly prominent feature as you head up or down the A40, but that is as close as most people get and this hill deserves a closer look. Made up of a diverse underlying geology combined with a large variation in uses over the years this hill now has diverse flora, fauna, habitats and features including an Iron Age hill fort, caves, old lime kilns and other sites of archaeological interest. And even trees planted in 1953 in contrasting foliage in the shape of the letters 'ER' to celebrate the coronation of Queen Elizabeth II just above Wyastone Leys on the south west corner of the woods.
The Geology
But I know none of that is of interest to you - you just want to know about the geology don't you?!
As mentioned this hill is made up of a diverse underlying geology from the Devonian Period, from about 416 to 359 million years ago, to the Carboniferous period and consists of quartz conglomerates, dolomite limestones and other sandstones but, so as not to confuse things, I will concentrate on the limestone of the limestone pavement that is the subject of this earthcache.
Limestone is a sedimentary rock and is formed when sea creatures died and sunk to the bottom of the sea, in this case a warm, shallow tropical sea that was here when this whole area was much closer to the equator as part of the Laurussia super-continent. Over millions of years these layers of calcium-rich shell built up and were compressed to form the limestone we see today.
Limestone pavement is a flat and exposed area of eroded limestone that resembles paved blocks. To create the limestone pavement though there were a few conditions that were needed, namely a wide, relatively flat area of limestone (this hilltop), vertical fissures in this rock and only a fairly thin layer of overlying soil and other rocks on top of this. What happened was is that the glacier cover on top of this (probably ice sheets of up to 1km thick) would have travelled their way across the landscape, removing the soil and other rock as it went and eroding the flat limestone smooth, the vertical fissures in the limestone would then have been subjected to water erosion and corrosive drainage and created distinctive channels in the surface at the vertical fissures giving the paved block look. These fissures are known as Grykes and the slabs inbetween Clints. When you visit you will see the Grykes very clearly as regular channels at the surface.
Visiting
Access is from two car parking areas that are marked as waypoints for you. If you approach from the west you will need to follow the obvious wide forest track in a zig zag fashion up the hill until you get to the top, where you can traverse south east across the open hill top straight to GZ. If you approach from the east you need to walk down the footpath from the car parking, past the caves on your left and then head slightly to the right down the footpath where you will soon see a small footpath heading west and uphill. You will eventually reach a stile next to a small wall which you need to go over and then head ahead to GZ within about 20 metres.
The stated co-ordinates take you to the small area of limestone pavement (it's not that big!) just inbetween a large, solitary beech and the footpath where there is a short section of four-railed wooden fencing. The limestone can get a bit covered by fern and suchlike but there is normally an exposed area close to the footpath.
The Tasks
To log this earthcache you will need to visit the co-ordinates, as stated, and send the answers to me to the questions below:
1) I mentioned the Carboniferous period earlier, but how long ago was this?
2) Take a close look at the limestone pavement and describe it, thinking of colour, surface appearance, surface texture, are there cracks or not etc
3) Look for the Gryke - how wide is it?
You do not need to wait until I reply to log your find, but I will come back to you to either confirm or clarify your answers as soon as I can. Photos are always appreciated too of course but are not a condition of logging.
| I have earned GSA's highest level: |
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Many thanks to The Woodland Trust for allowing me to place this earthcache here.