The Geological Survey on Eskdale iron ore

THE GEOLOGICAL SURVEY ON ESKDALE'S IRON ORE

Here is the description of Eskdale's iron ore deposits and mines from the Memoirs of the Geological Survey: "Special Reports on the Mineral Resources of Great Britain, Volume VIII: Iron Ores- Haematites of West Cumberland, Lancashire and the Lake District" by Bernard Smith, M.A., Sc. D. (H.M.S.O., 1919, with amendments from [second edition, 1924]):

NAB GILL MINE, BOOT, ESKDALE.
Mr. William Lazarus, Eskdale Green, Ravenglass.

Situated on the north side of Boot Station (Eskdale Narrow-Gauge Railway).
Maps: One-inch New series Ordnance, 38; Old Series Geological, 98 N.W.; six-inch, Cumb. 79 S.W.
No. 5 Level: Latitude 54° 23' 56". Longitude 3° 16' 16".

Geological Occurrence.
This mine affords an example of the occurrence of haematite-veins in the Eskdale Granite.
Ther mine has been worked at intervals since it was first opened as the 'Whitehaven (or Eskdale and Miterdale) Iron Mine' about 1870. It was reopened in 1917. The following account is based largely on J.D.Kendall's description (see here). The vein trends nearly N. 18° W., and has been worked for a length of 200 to 240 fathoms measured horizontally. It hades to the north-east at angles varying from 25° to 10° from the vertical. The trend of the vein at the surface, where it cuts a rising hill-slope, is more west of north than its true horizontal trend. Near the station it is at 200 ft. above O.D. Between 700 and 800 ft. O.D. a side-vein springs off in a north-westward direction.
The greatest width of the vein has been about 20 feet, including 11ft. of 'horse' or 'rider.' This was near the surface; farther down it was much narrower, and appeared to die out altogether at about 50 fathoms. An average width is from 2½ ft. to 3½ ft. Near the entrance to No. 2 level, 27 in. of small kidney-ore, forming plates on the foot-wall, were visible in 1917; there are also small 'country-veins.' The 27 in. of ore contained little 'riders' of granite, and the ore tailed off at one point to 18 in. In No. 5 level, where work was proceeding in July, 1917, the ore was only from 6 to 8 in. in thickness, and some of this was probably in a 'country-vein.'
Both the dip of the vein and its horizontal direction agree exactly with those of the large joints intersecting the granite. Near the surface the cheeks of the vein are decomposed to a width of from 1 to 2 ft., but in depth the belt of decomposition narrows. The cheeks are more decomposed where the vein contains ore than where it is barren. In No. 5 level the footwall shows vertical slickenslides.
The ore is a mixture of red earthy-looking ore, hard fibrous kidney of purplish tint, black oxide of manganese, reddish clay, grains of quartz similar to those in granite. Generally these various minerals are arranged in broken lines parallel to the sides of the lode, whilst occasionally a layer of 'smit' separates the ore and the granite. In some cases there seems to be a transition from ore to granite. 'Ring-ore' and stalactitic ore occur sparingly. Dolomite also is present in places united with ore, so that the two appear to be 'grown together.'
Reserves are problematic; their exploitation will depend largely upon the success attained in unwatering the mine. [1924: last sentence omitted]

Mining Details.
The vein was originally worked from five day-levels, between the 200 and 700 ft. contours. No. 3 has a concreted water-box to carry off the mine-water that used to sink to lower workings. In July, 1917, only No. 5 (the lowest) level was in use, and rise-working was in progess at about 300 yards from the entrance. The head of a dip-drift, following the vein downwards to the valley, is situated 240 yards from the entrance. A pump was being installed to deal with the water in this 'dib,' from which three lower water-logged levels are said to proceed.
In 1876 the output from the Eskdale and Miterdale Mine was 9,135 tons. These mines closed down in 1882, but reopened later. In August, 1917, the output was from 30-50 tons a week [1924 adds: but the mine was abandoned in July of the following year]. The ore was taken by the Eskdale Narrow-Gauge Railway to Ravenglass, and thence to an agent in the Whitehaven district.

VEINS AND OLD MINES
The following notes on old mines and veins of haematite are compiled from various sources, including the Mineral Statistics of Output, the One-inch and Six-inch Maps of the Geological Survey, and sundry publications. Of many of the veins no details are known, and as a working proposition they have no great importance, for most of them are difficult of access. The locations of the mines have been determined where possible, at least so far as the numbers of Six-inch maps are concerned.
Some of the veins traverse the Skiddaw Slates, some the Eskdale and Wasdale Granite and Ennerdale Granophyre, others the Borrowdale Volcanic Rocks.

One-inch New Series Ordnance Map, 38 (Ambleside); Old Series Geological, 98 N.W.
In addition to the Nab Gill Mine already described, the following mines and veins fall within this One-inch Map:-

Mine or Vein	District	Six-inch Map
South Cumberland Mine Red Brow Vein Brant Rake Vein Bigrigg Mines Birker Moor Mines Eskdale Moor Mine Dunnerdale Mines The Pillar and Red Pike Vein Green Gable and Great Gable Vein Red Tarn (Pike of Blisco) Vein Ore Gap Veins Green Hole Veins	Eskdale Eskdale Eskdale Eskdale Eskdale Eskdale Duddon Valley S.E. of Ennerdale Ennerdale to Great Langdale Great Langdale Bow Fell Bow Fell	Cumb. 79 S.E. Cumb. 79 S.W. Cumb. 83 N.W. ? Cumb. 83 N.W. & N.E. ? Lancs. 3 S.E. Cumb. 74 N.W. Cumb. 74 N.E., S.E. & 75 S.W. Westmor. 25 S.W. Cumb. 75 S.W. Cumb. 80 S.W.

[Smith then quotes Postlethwaite's description of the Eskdale mines, including Brantrake]

Brant Rake lies on the south side of the valley, south of the King of Prussia [1924: King George Inn], Eskdale Green, the footpath to Devoke water passing the old tip heaps from the levels. One or two veins here trend north-north-west and south-south-east. The ore mentioned by Postlethwaite as being obtained near the King of Prussia probably came from a vein, with eastward dip, that crosses the valley near Red How and extends north-westward across the Mite Valley almost to the foot of Wastwater. Its course in Eskdale is shown by the old dumps on the hillside about half a mile north-east of the inn. Several other haematite veins occur on both sides of the valley between and near eskdale Green and Boot, some crossing the Mite Valley to Wastwater. Their courses are laid down on the One-inch Geological Map. On the south side of the Esk some of the veins yielded a beautiful stalactitic form of haematite, and a little iron carbonate has been noted (MSS. Clifton Ward). Specular ore occurs in joints a little east of Stanley Gill and a little east of Linbeck Gill, on the south side of Eskdale.

Bigrigg Mines Nos. 1 and 2, Eskdale, the site of which is unknown [i.e. quite probably not in Eskdale at all, but near Bigrigg village] produced 2,174 tons of ore in 1882, and Birker Moor yielded 3,097 in 1881. Eskdale Moor Mine was merely a trial.

[The article then briefly describes the mines in Dunnerdale and Langdale]

At about the date (1700) at which the Great Langdale furnace was in operation, or perhaps a little later, ore was brought to a furnace in Langstrath from ore or Ewer Gap, at the head of the River Esk, between Bow Fell and Sca Fell Pikes. The veins run north-westward from Green Hole, and are also prolonged in a south-eastward direction. Of this locality Postlethwaite remarks [see also a report by Mr. Robert Woodley (of the Birker Moor Iron Mines) quoted by R. Meade in "The Coal and Iron Industries of the United Kingdom," 1882, pp. 417-8]: " There is a very large deposit of haematite ore at this point, but being at an elevation of 2,500 feet above the level of the sea, its position has been regarded as almost inaccessible for mining operations. . . . There are two veins, one on each side of Yeasty Rigg Gill (near Green Hole), at the southern end of the gap, each of them about 50 feet wide; the bearing of the western vein is a few degrees west of south and east of north, and of the eastern one a little to the east of south and west of north; these unite at the entrance to the gap. The deposit of haematite in the gap is of the finest quality, a considerable portion of it being kidney ore.

Another vein springing off these at Yeasty Rigg Gill runs a little east of north, skirting the western shore of Angle Tarn. The contents of these veins have been estimated in millions of tons.