Rockpools, Rocks and Rain at Crackington
Saturday 4th October did exactly as forecast - it rained, but that didn't stop 17 people and 2 dogs meeting up around a roaring log fire on Crackington Haven beach for talks on Crackington's unique geology and its rock pool inhabitants. Our guest experts for the day were Jane Anderson (geology) and Tim Dingle (biology).
Jane gave a lucid explanation of how the rocks known as the Crackington Formation were formed; how over 325 million years ago the area was in a shallow sea in the tropics where layers of mud and sand emitted from a delta built up during the carboniferous period. As the sea was squeezed out of existence by continental plates moving together the layers of sediment were compressed under a mountain range into the folds you can see today. Erosion and the effects of the ice age have exposed the coast as it is now.
The mudstones between the harder sandstone layers are soft and easly eroded leaving the harder more brittle sandstones to fall on to the beach - just to illustrate the point a lump fell as Jane talked!
The drizzle conveniently stopped as we cooked and ate our lunch, while muffins and chocolate cake miraculously appeared from knapsacks. This meeting was particularly important, being Brian's last one for some time as he takes a break from organising the group in order to globe-trot. We presented him with a bon voyage present of a portable hard drive to store all the pictures he takes on his travels.
Then it was Tim's turn to educate us. He gave an illustration of the types of seaweed commonly found and sent us off with nets and buckets to see what we could find. As the tide continued to recede we hunted under rock and weed for an assortment of creatures, which, although they may be considered pretty low down the cerebral scale, certainly know a thing or two about eluding slow humans. After about an hour we had found shore crabs, prawns, various molluscs, woodlouse shaped crustaceans called chitons, 3 types of sea anemone, an eel, shanny, blenny and the wonderfully named father lasher - a small fish with a spiny tail.
Everyone seemed to enjoy it despite the weather - the dogs certainly did.