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| Protected Sites |
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| Tideswell Dale , the Wye Valley SSSI,
Derbyshire |
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| Tideswell Dale GCR site is a disused quarry within
the Wye Valley SSSI, selected as part of a network of sites in the English Midlands
to demonstrate the volcanic history of the region during the early Carboniferous
(about 340 million years ago). At that time, there were a number of volcanic centres
in Derbyshire and other parts of the country. The volcanoes intermittently erupted
basaltic lava and ash into the tropical sea that covered much of the country at the
time. |
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| The Tideswell Dale GCR site contains lava flows
and a thick sill (lava which froze underground before reaching the surface).
The sill overlies a fine-grained clay-rich rock with a very unusual columnar
jointed structure. This material was covered by rubble and had not been seen
by geologists for many years. The main face of the quarry was also becoming
overgrown in places by scrub and sycamore trees. |
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| Two phases of enhancement works were performed on the site
in partnership with the Peak District National Park Authority, who own and manage the
site as a public recreation area. The first phase involved clearance of scrub and trees
from the main quarry face. The second phase involved digging a trench to re-expose the
base of the sill and the underlying columnar jointed material. This was performed in
July 2003. The columnar jointed material was discovered at a depth of less than a metre
below the surface. Samples were recovered for study and the trench backfilled to protect
the material from collapse and for safety reasons on a public site. |
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| The samples have been studied at Bristol and Oxford Universities. Preliminary results
of these studies suggest that some of the volcanic activity in Derbyshire may have taken
place in the early Jurassic, more than 140 million years later than previously thought.
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Temporary exposure of columnar jointed material, Tideswell Dale. |
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| Photo: Mick Murphy, Natural England |
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