Loch Leven, north side quarries, Ballachulish slate belt, Scotland
|From: Richey, J.E. and Anderson, J.G.C. 1944. Scottish slates. Wartime pamphlet No. 40. London : Geological Survey of Great Britain.|
North side of Loch Leven
As already mentioned, the Ballachulish Slates occur in two distinct geological structures, or folds, north of Loch Leven. In the more easterly fold, a direct continuation of the Ballachulish structure, the slate-rocks extend up steep hillsides, on either side of Callert House. No quarries have been opened in the outcrops concerned. In proximity to the main road along Loch Leven, there appears to be a considerable amount of overburden, and this factor coupled with the relative remoteness of the locality has, no doubt, been inimical to the exploitation of the occurrence.
The second fold, extending from Loch Level at North Ballachulish north-eastwards for many miles over high and remote country, contains an immense potential reserve of slate-rock. Except for the group of small quarries at North Ballachulish, however, practically no development has taken place. At the north-eastern end of the outcrop the Ballachulish Slates occur within three quarters of a mile of the Glen Nevis road, but they are here contact-altered by granite which forms much of the Ben Nevis massif. Farther south-west, at Blairmachfoldach, the slate-outcrop is crossed by the old Fort William – Kinlochleven road, but, as overburden is heavy, it might be difficult to find a face suitable for quarrying. Still farther along the outcrop the slate-rock is free from overburden over a wide area, but unfortunately lies largely above the 1,000-ft. contour (fig. 5). Outcrops occur less than a mile from the main Loch Linnhe road but, owing to their height and the rough nature of the intervening ground, would be difficult to exploit.
About three miles north of Loch Leven the slate-outcrop divided. The more westerly branch is narrow and interrupted by faults. It lies for part of its course close to, and only a few hundred feet above, the main road 1½ ml. N.E. of Corran Ferry. This occurrence was examined and appears to be unsuitable for exploitation. The slate, as seen in small hillside exposure, is much broken. While this might merely be a surface effect, it should be noted that adjacent hard siliceous flags are highly brecciated. Doubtless owing to the proximity of the major fracture which determines the course of Loch Linnhe. The area, too, is planted with trees, and the ground rises very steeply from the main road along the loch. The more easterly branch is up to half a mile wide and forms a continuous band which reaches the shored of Loch Leven at North Ballachulish, where it has been quarried (for details see below). A mile and a quarter north of the loch the same belt is traversed by Gleann Righ, up which there is a rough road from Onich. It is possible that a face suitable for opening up might be found in this locality.
North Ballachulish Quarry
Six inches to the mile: Inverness, Sheet 166 N.W.
|Locality||Half a mile N. by w. of North Ballachulish.|
|Access||Adjacent to main road and loch, where there is a pier.|
|Description of slate||Colour dark-grey: surface even; texture fine to medium. Pyrites (‘diamonds’) fairly abundant and sometimes of considerable size.|
|Dips, with amounts||Cleavage-dip, E. 30º S. at 70º (in W. part), E. 35º S. at 50º to 60º farther E. Bedding coincident or almost coincident.|
|Joints||One set of joints dips S. 35º W. at 30º, and another E. 35º N. at 45º.|
Details of workings
The slates have been worked in several openings in a rather haphazard manner across a wide outcrop. To W. there is a quarry (West Quarry) rising to a height of about 50 ft. in two benches. It contains a seam of apparently good slate, some 18 ft. wide, which is limited by a strongly pyritous band (crystals up to 1½ inches across) forming the W. wall of the quarry. On the E. side there is a band with quartz veins which shows rather wavy cleavage. Overburden is absent.
Immediately to the E., another opening, some 20 ft, wide, is filled with debris.
Still farther E. there is a larger working with a face about 50 ft. high, driven in a band some 40 ft. wide. The slate in this band is of variable quality, in some parts solid, in others much jointed.
On the hill-slope above the road-side quarries, a quarry of considerable size has been opened out, called the High Quarry. The slate-rock appears to be of good quality. At the present time a stream falls over the quarry face, but could no doubt be easily diverted.
There would appear to be a large reserve of good slate-rock available in the steep hill-side between the road and the High Quarry, should large-scale and co-ordinated operations be contemplated. The amount of debris, though large, could be conveniently dumped in the sea, though the proximity of the main road suggests that special arrangements for taking debris across it to the sea would have to be made.