Ebbor Gorge lies on the south west facing slope of the Mendip Hills and consists of a steep sided ravine cut into Carboniferous Limestone. A stream issuing to the west of the site runs down the tributary valley of Hope Wood before joining the main gorge. Millstone Grit and Lower Coal Measures form an impermeable floor to this valley. To enjoy this gorge, why not do Ebbor Gorge by Greyhead (GCB168) using the southern route before walking around the gorge to the north and finish off doing this cache. The gorge is the result of tectonics, or more accurately, faulting and water incision. All the stresses and strains produced by moving plates within the planet, builds up in the Earth’s rocky crust until it simply can't take it any more. All at once, CRACK!, the rock breaks and the two rocky blocks move in opposite directions along a more or less planar fracture surface called a fault.
There are three main types of fault:
Normal Fault
A normal fault drops rock on one side of the fault down relative to the other side. As you can see, the left hand side has moved down relative to the right.
Reverse Fault
A reverse fault or a thrust fault, is one where one rocky block is pushed up relative to rock on the other side.
Strike-slip Fault
Strike-slip faults have a different type of movement than normal and reverse faults. You probably noticed that the blocks that move on either side of a reverse or normal fault slide up or down along a dipping fault surface. The rocky blocks on either side of strike-slip faults, on the other hand, scrape along side-by-side.
After the area was moved by faulting, the rivers cut valleys down into the limestone, creating the famous gorges and caves.
To claim this cache you need to take a photo of you with a GPS and the gorge in the background from the co-ords given. You also need to email me with the answer to the following question:
What type of fault (and its name) have been exploited by the streams in the gorge?
