Skiddaw slate is an early Ordovician

Ordovician

The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...

 metamorphosed sedimentary rock

Sedimentary rock

Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....

, as first identified on the slopes of Skiddaw

Skiddaw

Skiddaw is a mountain in the Lake District National Park in England. With a summit at 931 m above sea level it is the fourth highest mountain in England. It lies just north of the town of Keswick, Cumbria, and dominates the skyline in this part of the northern lakes...

 in the English

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 Lake District

Lake District

The Lake District, also commonly known as The Lakes or Lakeland, is a mountainous region in North West England. A popular holiday destination, it is famous not only for its lakes and its mountains but also for its associations with the early 19th century poetry and writings of William Wordsworth...

.

The base of this series is unknown. The thickness could, therefore, amount to several thousand feet of sediment. These sediments were formed about 500 mya by deposition in a shallow sea, low-energy environment. The series contains differing grain sizes and comprises grit

Grit

Grit may refer to:* GRIT , also known as Arhgap32 or PX-RICS* Grit , a U.S. periodical founded as a newspaper in 1882* Grit , by Celtic fusion musician Martyn Bennett* Grit , by Norwegian rock band Madrugada...

s, flag

Flagstone

Flagstone, is a generic flat stone, usually used for paving slabs or walkways, patios, fences and roofing. It may be used for memorials, headstones, facades and other constructions. The name derives from Middle English flagge meaning turf, perhaps from Old Norse flaga meaning slab.Flagstone is a...

s, shale

Shale

Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...

s and mudstone

Mudstone

Mudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...

s.

In some places, there is evidence of intrusion

Intrusion

An intrusion is liquid rock that forms under Earth's surface. Magma from under the surface is slowly pushed up from deep within the earth into any cracks or spaces it can find, sometimes pushing existing country rock out of the way, a process that can take millions of years. As the rock slowly...

 of Skiddaw Granite into the Skiddaw Slates, close to the anticlinal axis of the Lake District.

Skiddaw slate has a grey hue (as opposed to Honister slate which has a green hue) and is used for building, in the Lake District. The traditional buildings of Keswick

Keswick, Cumbria

Keswick is a market town and civil parish within the Borough of Allerdale in Cumbria, England. It had a population of 4,984, according to the 2001 census, and is situated just north of Derwent Water, and a short distance from Bassenthwaite Lake, both in the Lake District National Park...

and other settlements are almost entirely of Skiddaw slate. The slate is also used for making souvenirs, monuments, ornaments etc. Smaller fragments are used for gravels, for ornamental pathways.