650,000,000 years ago, the south of England and Wales was 60 degrees south of the equator and part of the continent of Gondwana. Scotland and Ireland were several thousand miles away at the equator.
Earlier Precambrian volcanoes stood at the edge of a coastal plane and erosion washed sand and pebbles downstream, depositing the layers which form Haughmond Hill today.
In the late Precambrian, the horizontal layers were folded to become almost vertical. Hills were formed which, in turn eroded. This was so long ago that there were no animals or plants, and so no fossils.
Since then, the area has been under a tropical sea, washed by melting ice, a swamp, and a desert. When the last ice age retreated, 18,000 years ago, ice sheets scoured the hills into rounded shapes and the River Severn settled into it’s current easterly course through the Ironbridge Gorge.
There are two main types of Precambrian rock on Haughmond Hill – Greywacke and Conglomerate – with different uses. Crushed Greywacke is about the best road surface, remarkably non-skid. Conglomerate is crushed to be used in concrete.
Both rocks have been quarried for centuries and some was used at Haughmond Abbey. In 1950, large scale quarrying started and will continue till 2020.
It sounds like a disaster but, because the quarry is being dug down into the hill, you wouldn’t know about it till you reached the edge – carefully fenced, I hasten to add. Instead, a trail leads to it and a viewpoint explaining the geology, the workings, and the wildlife.
The rest of the area is beautifully wild but with good paths. We walked Mac there most days.
There are more photos at Picasa.
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