Something moved through the shallow tropical sea. As it came closer through the warm water it could be identified, from its iridescent sheen, as an ammonite, Psiloceras planorbis. This means that we are leaving the Triassic and entering the unknown future of the Jurassic, some two hundred million years ago.
The nearby land was moving slowly North from its present position about thirty degrees North of the equator. It would take the next two hundred million years to move to its present day location at fifty two degrees North – at about the same speed as our fingernails grow.
Storm clouds gathered and it started raining. It then rained some more and the rain became heavier as a tropical storm was created from the energy contained in the warm sea. The storm moved inland and the deluge increased as the clouds cooled during their climb over the mountains. Riverlets formed and began rushing down the steep mountains and across the coastal plain where they combined to form mighty rivers. These rivers carried grass, mud, trees and peat into the sea where our ammonite was unable to filter nutrients out of the normally clear, now heavily polluted, water. It suffocated and fell down through the water column to rest on the fine mud being deposited on the sea floor. It was soon covered and started its slow change into a fossil.
The storm eased and the sea water slowly cleared. There were some surviving ammonites. These were the ones that had managed to keep breathing and feeding during the mud onslaught and went on to breed so producing slightly different animals that had inherited the mutations that allowed their parents to survive. These are called Psilocera Liasicus.
This sequence of storms and clearing seas continued for many millions of years and can be seen, for example, on the foreshore at Kilve in Somerset where there is an alternating sequence of hard limestones and black shales.
These hard limestones are pale yellow-brown on the surface and a pale blue on the inside. They are known as the Blue Lias and make excellent building stones. They can be seen in buildings across Somerset.
Fred Mudlock put down his fourteen pound sledge and wiped his forehead free of the sweat and dust. He had been using the traditional quarryman’s technique of driving iron wedges in behind a block of limestone to ease it away from the quarry face. This method is slower than the blasting method that is used in aggregate quarries but this block would be used to make fully dressed building stones so the traditional method was still the best, even though it was hard work.
He was working at the Blue Lias face of Ashen Cross Quarry in Somerton, Somerset. The block he was freeing from its resting place was to be sawn to size and then used as facing stone ashlars for the new development just outside the village
Fred was buying one of these houses and so had specified Blue Lias stone for the window and door lintels – he would carve these himself and so have a real attachment to the house. How many people could say that they had wrenched some of the construction materials of their home from the living rock? He especially liked the ammonite fossil in the front door lintel that he had carefully carved around.
Fred had been living in this house with his family for twenty three years when he decided to downsize for his retirement and move to a two bed bungalow just down the road. Both children had got married and moved out so it was too big for the two of them.
The eager young estate agent arrived to survey the house, measure up and prepare the details.
‘How old is this house Mr Mudlock?’ he asked
‘A little over two hundred million years,’ said Fred.
© Richard Kefford Eorðdraca
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