Reflecting the past- fox holes'n fossil landscapes EarthCache

Fox Hole Cave is a SSSI for geological and archaeological interest and is situated on High Wheeldon Hill which is owned by the National Trust. The cave is important because of its fossiliferous deposits and the area more generally is of outstanding beauty.

You have climbed to the top of High Wheeldon and have reached the trigpoint. Now use your GPS to face North West - compare the view in front of you with the modified photo below.

Picture this - you are floating without a care in the world in a small boat (which is facing North West) at a latitude perhaps 5^o SOUTH of the equator! Beneath you, the azure blue sea laps gently against the hull; the tropical sun beats down on you from above; it's hot, perhaps uncomfortably hot(especially on land) but for now you are enjoying the cool sea breeze. To your left, the water under your boat quickly becomes deeper; the sea bed falls away here. The shore is to your right. Directly underneath you is a coral reef teeming with life; brachiopods, crinoids, fish (bony as well as cartilaginous), corals and many more creatures besides - all competing for food, a space to live and trying to keep out of the jaws of predators.

To your right - there is a shallow shelf of land which is submerged underwater forming a lagoon filling slowly with the remains of dying sea microorganisms. Their tiny skeletons piling up to form a white calcium carbonate ooze. To your left the coral reef fringe drops away into the deep blue depths of this ancient sea.

Your mind is now picturing the scene at this location under your feet about 300 million years ago in a time known as the Visean age which is a part of the Carboniferous period. (Your are on top of a hill which was a fringing reef on the SW edge of the shallow shelf sea). Britain lies very far to the south, on the equator or the other side of the equator; the dinosaurs will not arrive for another 100 million years or so; humans, even our most distant and primitive ancestors will have to wait for over 330 million years to enter onto the stage of life. It is about this time that some of the early amphibians (see image of Crassigyrinus an early amphibian found in Scotland) are moving onto land and reptiles are evolving for the first time in life's long history. Geological time is mind-bogglingly vast!

In the ancient sea, there were many types of fish; both bony fish and sharks (cartilaginous) and their relatives. Some of the sharks were very strange; look at Stethacanthus, a shark with an anvil shaped dorsal fin.

So back to today

You are standing at the trigpoint on top of High Wheeldon still looking NW along the line of hills. High Wheeldon and all the other hills in the chain stretching in front of you are strange, being composed of two types of limestone. To your left (SW) the bedrock is Apron reef limestone (purple in the photo). To your right(NE) the other half of the mountain consists of Bee Low Limestone.

This 50:50 pattern of bedrock repeats itself in all the hills you see stretching out in front of you. (The purple shading on the aerial photo shows the Apron reef limestone). The rock towards the bottom of the photo is younger Millstone grit; this is the next body of rock formed after the limestone but before the coal bearing rocks were deposited - all the rocks are from Carboniferous period.

An apron reef is a structure which forms a short distance away from the shore due to the build-up of mainly coral skeletons over thousands or even millions of years. Some scientists think that Apron reefs are just young fringing reefs (where short lengths of reef simply haven't joined together yet); others think they are just a type of fringing reef (but generally shorter in length) and form on headlands and other promontories.

The best place to see the two types of limestone is not from the top of the hill but by visiting the gorge between High Wheeldon and Aldery Cliff. Park at N53^o 11.635 W001^o 51.288 and walk up and down the lane; the two limestones are clearly visible in the quarry and outcrops on either side of the lane. The Apron reef limestone will yield fossils if you look closely (but please don't go chipping away at the rocks; look at the broken scree material).

Since this hill is made from limestone it is no surprise that a cave has formed within this dissolvable rock. Take a walk to see the entrance to Fox Hole Cave (N53^o 11.562 W001^o 51.134). This is a very important karst (limestone) feature because within it, soils have been deposited which contain the bones of extinct animals that lived in this area during the last cold snap called the Devensian Cold Stage of the Pleistocene period! Believe it or not, the bones of bears and lions amongst others have been found in the cave and so it has been designated an SSSI because of its valuable fossiliferous cave earth. (I think Bear cave or Lion cave might be more appropriate than Fox Hole cave!). It is possible to explore this cave by making an arrangement directly with the National Trust; the details of whom to contact can be found on a plaque at the entrance of the cave itself (so you just have to visit or do some research!

The calm tropical sea lasted for about 20 million years; but later into the Carboniferous period, the landmass further south and the landmass north of this area were pushed together by forces known as plate tectonics. This displaced the sea and caused the land to rise. It was this change, from submerged underwater rocks to raised land areas with rivers flowing south (carrying sand etc), that created the sandy Millstone grit (if you look south from the trigpoint you can see land which is made mainly from Millstone grit). By the end of the Carboniferous period; the sea had entirely disappeared and the geological clock had now moved into the Permian period. The closing of the sea and the rising of the land was caused by the Variscan orogenic event (it is also called the Armorican, Hercynian and Carbo-Permian Orogeny: they are all the same thing!).