I was showing my daughter the
prominent bands of Sandstone rock that lies at the bottom of Broad Street and on the road to Cheddleton.
They are noticeable by pebbles stuck in the rock like currants in a cake. The
quartzite pebbles are very smooth and suggest that they were once part of a
fast flowing river system. It must have been a formidable obstacle to the 19th
century road builders blasting their way through the town.
I was right. The Sandstone dates
from the Triassic period of around 250 million years ago at a time when life on
Earth nearly came to an end. Other rocks around Leek are older; the grit stones
of the Roaches are from the Carboniferous period of 380 million and the
limestone of the White
Peak marking the one time
existence of tropical coral sea date from 340 million years.
I have always been interested in
the age of the Earth, which irrespective of what Creationists might think, is
about 4 billion years old. Recently, I bought a book on a history of the Earth
and I looked up the early Triassic period and how the area might have looked.
During this period there was only
one Continent called Pangea. Britain
lay near to the ocean that circled Pangea called Tethys and was closer to the
equator. The Leek deposit is part of a larger group called Sherwood Sandstone
covering areas out to Cheshire
and eastwards towards Nottinghamshire.
Weather conditions during the early Triassic
were monsoon- like in this time which accounts for the pebbles worked smooth by
the deluge and indicate a delta type area similar to the Nile
today. Temperatures were high and a desert climate existed. It was a forbidding landscape with little
life. Few fossils exist in the local rocks. Later in this epoch however the
first dinosaur made their impression on the landscape.
Chirotherium, a crocodile-like ancestor of the
dinosaurs, left five fingered hand-prints behind in the sand which were found
millions of years later by fossil hunters. A fine example can be seen in the World Museum
in Liverpool found in a sandstone quarry
on the Wirral.
The Triassic period saw a long
process of re-birth after the calamitous previous era- the Permian- when the
planet saw a Mass Extinction event with increasing volcanic activity, methane
release and acidification of the seas resulting in raised temperatures and the
extinction of around 90% of all species on the Earth. It was called the Great
Dying. It took the planet millions of years to recover and the rocks in the
south of the town bear witness to a period when the Earth was recovering from
this cataclysm. It was the greatest Mass Extinction event of which there have
been five. Scientists think that the current global warming might result in the
sixth Mass Extinction event now.