The house 19th March 2013
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 slighty 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.
*
http://www.ashencrossquarry.co.uk/
