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Caer Caradoc

Caer Caradoc is one of the Stretton Hills.  It helps to make the east slope of the Stretton Valley opposite the Longmynd. It makes a very good view point and to add further interest there is also an Iron Age fort on the top.

This part of Shropshire during the late Precambrian was at the margins of an ocean where two tectonic plates were coming together.

The plate to the west (as it it today, towards Wales) was moving into the plate to the east (in the West Midlands). Their zone of contact was in the vicinity of the present-day Stretton Valley, along a gigantic crack through the Earth’s crust that we now know as the Church Stretton Fault Zone In fact there are a whole series of cracks that make up the Fault Zone, and Caer Caradoc lies between some of them – see map – (‘F1’ to the west (top) and ‘F2’ to the east; a further fault, ‘F3’, lies still further east). Edgar Cobbold in his retirement produced a remarkable map of this area, published in 1927 and reproduced here with kind permission of the publishers: the Geological Society of London (who retain the copyright).

Caer Caradoc
Cambrian of Comley area
This work was greatly facilitated by Cobbold’s local contacts and his friendships with local farmers, persuading many of them to dig pits in the places where he wanted to see the underlying rocks – a luxury not usually furnished to geological investigators!

The westerly plate sank beneath the easterly one and as it did so the sediments became piled up, forming the thick sequence we see today within the Longmynd.


Looking down into the Stretton Valley from Caer Caradoc it is hard to believe that you are looking at a tear in the Earth’s crust, a fault line that was once as active as the famous San Andreas Fault in California!

As the westerly plate sank deeper into the mantle so the heat caused partial melting and volcanoes developed above, within the easterly plate. Their lavas and intrusions formed the rugged crags of Caer Caradoc and its associated hills. However, the volcanoes released a lot of ash and this accumulated as beds within the sedimentary sequence, known as Tuffs.

Caer Caradoc – FOSSILS

You can follow in the footsteps of one of the founding fathers of modern geology when you step into Comley Quarry, on the north side of Caer Caradoc. This is where a man by the name of Charles Callaway came to study Trilobites, and he found what were then the oldest in the whole country: Callavia. Photographs and details of the trilobites are here in our proceedings article. Through studying these now extinct creatures, geologists have been able to tell us a lot more about what the environment was like in the early part of the Cambrian age for the earliest creatures with hard body parts.

Comley Quarry is a SSSI (click here to see the reasons for notification) and is now managed by the Shropshire Wildlife Trust as a Nature Reserve.

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