Roofing Slate Metamorphic
Millstone Grit and other Carboniferous Sandstones Carboniferous These sandstones from the Upper Carboniferous, Millstone Grit and Coal Measures, produced some of the strongest andmost durable stones used in Britain. They were particularly widely used for major engineering projects such as reservoirs, quaysides and bridge building. In Yorkshire, where the greatest concentration of working quarries still occurs, these pale yellow- brown to grey sandstones are commonly known under the generic name ‘York Stones’. Many of Yorkshire’s industrial towns and cities (eg. Leeds, Bradford, Halifax and Huddersfield) are built entirely of these local sandstones or gritstones.
Geographically, a slate is a fine grained metamorphic rock with a pronounced cleavage. It is this cleavage, which enables themason to split the rock into thin sheets. The second notable characteristic of a slate is its relative impermeability which makes it an ideal roofing material. Five areas of Britain have produced high grade roofing slates, in some cases, for several centuries. In Scotland, slates were produced at a number of quarries, which all have now ceased operation. In Cumbria (green and blue slates) and in NorthWales (purple and blue-grey slates) slate production is very much active.
Welsh Assembly Building
Hebden Bridge
Welsh Slate
Welsh Roofing Slate
Photo ©Ceri Thomas (cc-by-sa/2.0)
In Leicestershire, production has long been abandoned. In the SouthWest, slates were once quarried very extensively in numerous small local quarries. Larger operations are still active at the Delabole quarries.
M1160N Seclusion
B9760G
C6850G
B4840G
B9630K
W8080X
SX
SX | SD
SX | SD
SX
SX
SX
V5111K
B4310F
Goldfinch
H8180J
Y0081Z
Olive D8270S
SX
SX
SD
SX
SX
SX
15
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