An Online Community Newsletter published by the Pencoed Town Council
A Long, Long Time Ago
Looking back into geological time, the area that is now Pencoed has had an immensely long and eventful - sometimes catastrophic - history. This history is written in the rocks and the landscape of the area.
To the south of the town, are the rolling hills of the Vale of Glamorgan. The rocks at this point consist of hundreds of feet of limestone laid down in a shallow, tropical, coral sea some 400 million years ago.
Lying on top of this, are hundreds of feet of Millstone Grit, a silt stone laid down under shallow estuarine conditions. The tropical, marshy conditions that prevailed at the time were the precursor to the vast swampy forests that were one day to become the South Wales coalfield. This forms many hundreds of feet of silt stone, clays and coal seams to the north of the town.
Towards the west of the town, a deposit of limestone conglomerate forms the woodland ridge called Coed-y-Mystwr. This is a red sandstone matrix containing round pebbles of limestone; probably a result of the land being uplifted into dry desert conditions some 280 million years ago. The rock was possible formed in a desert depression by violent floods.
There is little evidence around the area of what happened for the next 276 millions years, though the area probably saw the dinosaurs come and go. The next events recorded start around 4 million years ago with the coming of the ice age. It was this event that shaped the present day landscape. The area was on the very edge of the ice sheet, which left huge deposits of glacial clay, boulders, sand and gravel in the Ewenny valley.
To the south of the town, are the rolling hills of the Vale of Glamorgan. The rocks at this point consist of hundreds of feet of limestone laid down in a shallow, tropical, coral sea some 400 million years ago.
Lying on top of this, are hundreds of feet of Millstone Grit, a silt stone laid down under shallow estuarine conditions. The tropical, marshy conditions that prevailed at the time were the precursor to the vast swampy forests that were one day to become the South Wales coalfield. This forms many hundreds of feet of silt stone, clays and coal seams to the north of the town.
Towards the west of the town, a deposit of limestone conglomerate forms the woodland ridge called Coed-
There is little evidence around the area of what happened for the next 276 millions years, though the area probably saw the dinosaurs come and go. The next events recorded start around 4 million years ago with the coming of the ice age. It was this event that shaped the present day landscape. The area was on the very edge of the ice sheet, which left huge deposits of glacial clay, boulders, sand and gravel in the Ewenny valley.
Not So Long Ago
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