Despite the wettest April since records began, 10 CAN stalwarts turned up on a beautiful (but windy) April morning at Derbyshire Bridge Car Park at the top of the Goyt Valley for the first CAN Geologic Field trip.
Geology and Paleontology is the basis of the original definition of Natural History and considered as such long before Darwin had a good idea.
Led by the enthusiastic Richard Langthorp we assembled for the introduction and examples of what we are likely to find. Richard started off by talking through the features of a Geological map and then an explanation of the climate and the landscape at the time of the Carboniferous – essentially, a tropical rain forest adjacent to a huge (Mississppi sized) river delta. He presented a couple of fossils that had been ‘rescued’ from a coal seam only a few metres from where we had met.
As we wandered down the road towards the Goyt Valley, there was plenty to keep us occupied, various Mosses, Lichens, moorland birds and you just can’t help tripping over the local invertebrates..
There was a brief stop at an exposure where Richard showed how the land had faulted and a number of other geological features that could be indentified and used to make an assessment of the environmental conditions at the time.
We stopped for lunch at an old quarry. This gave Richard the opportunity to show an important feature known as cross bedding. Cross bedding is formed by the migration of the river channels leaving a characteristic slanted patterns in the rock face. The size of the grains and the angle of the beds give a very clear indication on the speed of the flow of the river and how fast the channel is moving.
Following a short lunch break, we headed up into the moors. The evidence of the excessive rain was all too apparent with streams in full flow, bogs being very boggy and mud being of the suction kind… However, onwards and upwards, the sun was still shining.
After a fairly brisk walk, Richard brought us to a stream where there were examples of Lepidodendron fossils. This tree had a rigid bark like exterior with leaves that grew directly from the ‘trunk’. The inner of tree was a very soft plant like structure that provided no real support. The tree would grow to about 30m in height and as the leaves dies away, would leave a characteristic diamond pattern on the trunk. The tree would propagate by releasing millions of spores from its canopy and then would simply die.
Adjacent to the Lepidodendron fossils in Image 5 there was a beautifully preserved stem of a Calamites tree. These are the extinct relations of horsetails today and you can see the cylindrical section and ribbing parallel to the length of the stem characteristic of this plant. One of the differences between present day horsetails and their extinct cousins is the size – the fossil stem we saw had a diameter off over 20cm, very tree-like in scale, whereas horsetail stems generally are less than 1cm in diameter.
Just up the path from these fossils, Richard pointed out a fossilised root from a Lepidodendron tree. Note that the red colouring is natural and had clearly leached into the rock during the mineral substitution process that creates fossils. Note also the puncture holes in the rock where the rootlets branching off from the main root stem have broken off, leaving these indentations.
The walk then continued over toward Shining Tor and then back to the Car Park. During this time, Richard answered questions and gave examples of how the different rock types had shaped the Cheshire and Derbyshire hills.
During this time, Ralph manged to trip over another (unidentified) fossil – potentially a new discovery.
The walk finished on time at about 2:30, with about half of us winding up at the tea rooms for tea and teacakes. A superb, interesting and educational day out and many thanks to Richard for hosting it.