(Page created 19/04/05. Last updated 04/05/14)
The building of the Lake District
Imagine thick layers of materials – mud, sand, ash, lava, and more – laid down over millions of years, new on top of old. Imagine the materials in these layers changed by heat and pressure, and then squeezed up into a dome. Imagine the top of the dome eroded by weather to expose the oldest layers in the centre, whilst remaining covered by the newer layers further out.
This picture of how the rocks that make up the Lake District got to be where they can now be found is of course very much simpler than what happened in reality. This is not the place for such complications, but the Cumberland Geological Society in their guide to the Lake District describe a useful model that adds a little more colour to the basic picture, relating the stages of deposition of materials, and their folding and erosion over the past 500 million years. They also give a useful reminder that our region’s position has changed over time during this period, both in terms of how close it has been to the equator, but also relative to sea level – sometimes above, sometimes below. The sequence of events in the model is as follows:
The oldest rocks in the region (c.500 million years ago) – were laid down as muds and sands on the bed of an ancient ocean, but have been much changed since, resulting in what we now refer to as Skiddaw Slates. These make up the slates and flagstones of the Northern Fells.
After a period of folding and erosion these were overlain (450) during two periods of volcanic activity by lavas, tuffs (ash) and agglomerates (rocks), more than 4000 metres thick. The second major volcanic outburst formed rocks of the Borrowdale Volcanic Group. These make up the fells and valleys of Central Lakeland.
The region was invaded by the sea to produce firstly a thin layer of lime-rich fossiliferous mudstones known as the Coniston Limestone Group (now running across Lakeland from MIllom to Shap), and later (420) by muddy and gritty sediments referred to as Silurian rocks (of Southern Lakeland)
A collision of two continental masses (400) had three major effects : an arching up of the region, severe squeezing and folding of layers, and the introduction of a granite mass beneath the whole (now exposed in a number of places including Ennerdale and Threlkeld)
Erosion to a rocky landscape of low relief over which tropical seas advanced and retreated (300), creating layers of limestone (from when underwater) – as in Furness, sandstone (from desert conditions), and coal measures (from swampy deltas) – as at Whitehaven.
More folding and erosion, followed by deposition of sandstone (as at Penrith and St.Bees), shales and limestone during Permian (250) and Triassic (200) times.
Since then gentle uplift and erosion, possibly overlain by Jurassic and Cretaceous seas, but certainly affected by glacial activity in relatively recent times.
Cumbria sites listed in the MMP Step Three report on the quarrying industry:
315 sites throughout England and Wales are listed. 14 are graded +++, 5 of them in Cumbria
|Crowdundle Roman quarry||?|
|Honister slate quarry, 1643-1986||NY 215 140||++(+)||Adit (copper), adits (x32), dressing shed, bothies, office, quarries, hopper, ropeway, smithy|
|Gerrard House Roman quarry||NY 255 462||++||Quarry|
|Tilberthwaite slate quarry, C18-1930’s||NY 306 007||++||Adit, stable, dressing shed, hut, spoil heaps, tramway, working face|
|Hodge Close quarry, 1780’s – present||NY 317 020||+++||Adit, chapel, dam, engine bed, housing, incline, railway, ropeway, spoil heap (multi-finger)|
|Threlkeld micro-granite quarry, 1870’s-1980’s||NY 328 263||++||Crushing mill, incline, quarry, railway, spoil heap (multi-finger), engine shed|
|High Quarry, Troutbeck Park, 1753 – C20||NY 430 069||+++||Adit (x4), office (x2), weigh house, dressing shed(x6), incline, leat, railway, roadway|
|Wetheral Roman quarry||NY 466 535||++||Working face|
|Wrengill quarry||NY 475 086||++||Adit, dam, dressing shed (x2), engine house (pelton), leat, quarry, smithy (and housing), other structure, tramway|
|Stockdalebank, Longsleddale, 1724-80||NY 487056||++||Dressing shed, quarry, roadway (sled), spoil heap|
|River Gelt Roman quarry||NY 527 587||+++||Spoil heap, working face|
|Pigeon Crag Roman quarry||NY 531 580||+||Working face (?)|
|Coombcrag Roman quarry||NY 590 650||+++||Spoil heap, working face|
|Whinney End slate quarry, early-middle C19||SD 250 833||R||Crane (base).dressing shed (x4), quarry, roadway, spoil heap|
|Coniston Old Man slate quarry, C16-C20||SD 280 980||+++||Adit (many), stables, dressing shed (x9), office, pipeway, quarry, railway, ropeway, smithy, spoil heap, stone sawing mill|
|Underbarrow quarry, C19||SD 484 924||0||Quarry|
|Stainton quarry, 1866-||SD 548 727||?|
|Hutton Roof quarries, C19-1910s||SD 571 770||R||Building, quarry, roadway|
The grading system:
+++ Site of exceptional national importance, for which statutory protection will almost always be appropriate, and preservation will be of high priority
++ Sites of clear national importance, for which statutory protection will normally be appropriate
+ Sites of national importance, but of lesser priority for resource allocation
R Sites of regional rather than national importance for this industry
0 Sites which are believed to have been destroyed, or never existed at the location reported
? Insufficient information or lack of access rendered accurate assesment impossible
The Dentdale Marble Industry (article)
The quarries of Lakeland : David Glover, Bookcase (Carlisle), 2014