Geology

The Church Stretton area includes some of the most fascinating geology within the British Isles, situated as it is astride the famous Church Stretton Fault, and with some of the oldest rocks in England, over 560 million years old, forming the well-known hills either side of the valley.

Raindrops captured forever?

The sandstone of the Long Mynd as well as the surrounding volcanic hills, bear witness to eruptions, raging rivers, seashell depositions as well as what was thought to be imprints of raindrops from passing rain showers some 565 million years ago. The geology round Church Stretton is complex and fascinating, with some of the oldest rocks in England coming together in one place (11 out of the 13).

In 2011, Dr Alex Liu from Cambridge University and Professor Martin Brasier from Oxford University, examined the "raindrops" under a special microscope and discovered that they were not raindrops at all but were 'beltanellaformis minutiae', the very first life forms on the planet, right here on the Long Mynd. More information can be found in the National Trust's exhibition in the tearoom of its Carding Mill Valley premises west of the Shrewsbury road. 

58The rocks of the Longmynd on the west of the town, and also those which make up the Stretton Hills to the east, were formed during the ancient Precambrian period. Plate Tectonics now shows us that during the late Precambrian period around 566 million years ago the Shropshire area along with the whole of southern Britain lay close to the Antarctic Circle at around latitude 60 degrees south of the equator. Shropshire lay under a shallow sea in which volcanic islands erupted large amounts of the volcanic lava and ash and earthquakes formed major faults in the Earth's crust, the largest of which was later to become the famous Church Stretton Fault.

The volcanic lavas and ashes now form the Stretton Hills to the east of the Church Stretton valley including the hills of Caer Caradoc, the Lawley and Ragleth Hill, as well as the famous Wrekin further to the north east. At the same time as the lavas and ashes were being erupted sediments were being laid down in shallow seas nearby and these sediments were later hardened to form the obvious layered sedimentary rocks, mainly sandstones and shales, of the Longmynd. After formation of the sedimentary rocks of the Longmynd and the lavas and ashes of the Stretton Hills the area was subjected to violent earth movements which folded up the rocks and arranged the sedimentary rocks in steeply inclined layers which can be seen in the sides of the deep valleys of the Longmynd .

During the succeeding geological periods of time the Church Stretton area was for many millions of years under the sea or uplifted as land, but always moving steadily north due to continental drift. During the Silurian period around 420 million years ago the famous limestones of Wenlock Edge were formed as tropical coral reefs when Shropshire lay very close to the equator. Although Wenlock Edge is some distance away to the east of Church Stretton some of the limestones can be found in the Church Stretton valley having been pushed down into the valley along the Church Stretton Fault.

The Church Stretton valley started to form around 50 million years ago as uplift of Shropshire was followed by erosion in a sub-tropical climate along the Church Stretton Fault. During more recent geological times the Church Stretton valley was occupied by the ice sheet which spread down from the Irish Sea area around 20,000 years ago. The Longmynd itself was not covered by ice but almost certainly had permanent snow fields. During the melting of the ice and snow fields sheets vast amounts of melt waters cuts the deep valleys of the eastern Longmynd such as Cardingmill Valley and Ashes Hollow.

The floor of the Church Stretton valley is occupied by sands, gravels and clay much of which was eroded away from the slopes the Longmynd and deposited by melt waters in the valley. Happily, earthquakes are rare events along the Church Stretton fault today, but in 1990 an earthquake along the nearby Pontesford-Linley Fault registered 5.2 on the Richter scale.