Dorothea quarry

Dorothea quarry is a disused slate quarry in the Nantlle Valley in North Wales. It covers a large area around Talysarn and contains three flooded deep lakes within the site.

Dorothea
A flooded pit in the quarry in July 2010
Location
Dorothea
Location in Gwynedd
Locationnear Talysarn
CountyCarnarvonshire (now Gwynedd)
CountryWales, UK
Coordinates53°1′30″N 4°17′0″W
SH 518 503
Production
ProductsSlate
TypeQuarry
History
Opened1820s
Closed1970 (1970)

History

Dorothea commenced working in the early 1820s, though there were a number of smaller workings on or near the site before this. By 1848 it had become the dominant quarry in the area, employing 200 men and producing 5000 tons of finished slate. Production peaked in 1872 at 17442 tons. In the 1930s over 350 men were employed at Dorothea. Production dropped significantly after the start of World War II and the quarry closed in 1970.[1]

Since quarrying ended in 1970, the Dorothea quarry has flooded and become a popular site for scuba diving (even though there are no facilities provided, and diving is officially banned in the quarry); the unregulated nature and depth of the site has encouraged some divers to overestimate their capabilities in the decade 1994-2004, 21 divers lost their lives in the quarry.[2]

Description

The quarry sits at the bottom of the wide Nantlle valley and consists of six pits, the deepest dropping 106m from the surface. The slate veins here run vertically, allowing unusually deep vertical pits to be dug. Because the pits fall below the water table they needed to be constantly pumped to stay dry. A Cornish beam engine was installed in 1904 to pump the pits; it stayed in use until 1951 when it was replaced with electric pumps.[1] This was the last new Cornish engine to be built.[lower-roman 1] It remains in situ in its Grade I listed engine house.[3]

Transportation

The quarry was one of the first users of the 3 ft 6 in (1,067 mm) Nantlle Railway in 1828. It later developed an extensive internal tramway system of 2 ft (610 mm) gauge. Dorothea was one of the first users of De Winton locomotives in 1869.[1]

Locomotives

2 ft (610 mm) gauge locomotives known to have worked at Dorothea.

Name Builder Works No. Date built Type Notes
Dorothea Hunslet 763 1901 0-4-0ST Worked until 1942. Now preserved on the Launceston Steam Railway[4]
Wendy W.G. Bagnall 2091 1919 0-4-0ST Purchased from the Votty & Bowydd Quarry in Blaenau Ffestiniog in 1930. Preserved by the Hampshire Narrow Gauge Railway Trust[5]

References

  1. Another engine was installed later at Hodbarrow Mine, Cumberland, but this was an older engine, re-located.
  1. Richards, Alun John. The Slate Regions of North and Mid Wales. pp. 70–71.
  2. "Why Dorothea claims lives". North-west Wales News. BBC Online. 22 March 2004. Retrieved 16 March 2007.
  3. "Cornish Beam engine, Dorothea Quarry, Dyffryn Nantlle". The Slate Industry of North and Mid Wales. Retrieved 21 February 2019.
  4. "Dorothea". Launceston Steam Railway. Archived from the original on 8 November 2014.
  5. "Dorothea Slate Quarry". The Narrow Gauge Railway Museum.
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