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October 1977 IndexBulletins Index

Caithness Field Club

Caithness Field Club Bulletin
1977 - October

J. Saxon

Baligill resembles nothing so much as a fragment of Caithness which has wandered into Sutherland. It stands on a narrow wedge of Old Red Sandstone bounded by the metamorphic rocks of east Sutherland. A fairly abrupt change in vegetation marks the limits of the Baligill outlier since the middle Old Red Sandstone is calcareous.

The Baligill outlier is fossiliferous. The first mention of it in the literature was in 1878 when Geikie (Old Red Sandstone of Western Europe) records fossils from the locality without actually naming it. The fishes he recorded were: Osteolepis macrolepidotus, Coccosteus cuspidatus and Dipterus valenciennesi, a self-consistent fauna typical o the Achanarras horizon.

The next mention of it, by name this time, was by Crampton and Carruthers (The Geology of Caithness, 1914). They included it, though in Sutherland, because of its affinities with the Middle Old Red Sandstone of Caithness. The fishes they recorded were: Thursius macrolepidotus, Coccosteus cuspidatus and Pentlandia macroptera. Now it is possible for one not well versed in taxonomic science to confuse Osteolepis with Thursius and Dipterus with Pentlandia. The fauna are, however, not consistent as Th. macrolepidotus is characteristic of the Wick Flags and the Helman Head beds where it is found with Dipterus. Coccosteus is, to all intents and purposes an Achanarras horizon fish. Pentlandia, however is a John o' Groats Sandstones fish.

Miles and Westoll (Two New Genera of Coccosteid Arthrodira and their Stratigraphical Distribution, 1963) drew attention to this inconsistency.

The present author (Fossil Fishes of the North of Scotland, 1975) recorded the fishes from Baligill as: Osteolepis macrolepidotus, Coccosteus cuspidatus, Dipterus valenciennes, and Cheirolepis trailli. This is a consistent fauna since the three fishes, 0. macrolepidotus, C. cuspidatus, and Ch. trailli are confined to the Achanarras horizon. Ecologically, however the Baligill fauna is more akin to that of the Sandwick Fish Bed in Orkney which is the same horizon as Achanarras.

A further visit was paid to Baligill during August 1977. This time a further fossil vertibrate was added to the writer's checklist: Palaeospondylus gunni. This "fish" is again confined to the Achanarras horizon. It is worthy of note that, outside Achanarras itself only isolated finds have been made of this fossil: a single specimen (Crampton and Carruthers 1914) from Niandt in Caithness, a single specimen (Prof. T. S. Westoll pers. comm.) from Quoyloo, Orkney (Sandwick Fish Bed = Achanarras Horizon) and, since finding this, one specimen from Baligill (Prof. T. S. Westoll, pers. comm.).

The calcareous rock of the Baligill fish bed is so rich in CaCO3 that it was once quarried for lime burning and field students of archaeology will find a fairly large number of lime kilns in the outlier. Of further interest to the industrial archaeologist is that it appears that the fish bed was mined at one time by the room and stoop method. This consists of removing the economic seam of mineral, leaving pillars of the seam to support the roof bed. It is something of a puzzle to know how this old method of mining was introduced to the quarrymen but it is just possible that the Brora coal mine was once mined in this way and the idea may have come from there. This method was in common use in the previous century in the Midland Valley of Scotland though there are few examples which can still be seen by the general public. This method of mining is, so far as is known to the writer, unique in the Scottish Highlands.

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