188 Scientific Intelligence.— ^Geolog^y. 



GEOLOGY. 



8. On the Coal-field of Brora in Sutherland. — Our active 

 and intelligent friend, Mr Murchison, Secretary to the* Geo- 

 logical Society, in a paper lately read before the Geological 

 Society, gave an interesting account of the Coal-field of Brora, 

 in Sutherland. Having, several years ago, examined the Brora 

 district, we can bear testimony to the accuracy of the following 

 details of Mr Murchison : — " The Brora coal-field forms a part 

 of the deposits, which on the south-east coast of Sutherlandshire 

 occupy a tract of about twenty miles in length, from Golspie 

 to the Ord of Caithness ; and three miles in its greatest 

 breadth ; — divided into the valleys of Brora, Loth, and Na- 

 vidale, by the successive advance to the coast of portions of the 

 adjoining mountain range which bounds them on the W. and 

 N.W. The first of these valleys is flanked on the S.W. by hills 

 of red conglomerate ; which pass inland on the N.E. of Loch 

 Brora, and give place to an unstratified granitic rock, that forms 

 the remainder of the mountainous boundary. With a view to 

 the comparison of the strata at Brora with those of England, 

 the author had previously examined the N.E. coast of York- 

 shire, from Filey-Bridge to Whitby, comprising the coal-field of 

 the Eastern Moorlands above the lias. The highest beds at 

 Brora consist of a white quartzose sandstone, partially overlaid 

 by a fissile limestone, containing many fossils, — the greater num- 

 ber of which have been identified with those of the calcareous 

 grit beneath the coral rag ; — and along with these Mr Sowerby 

 has discovered several new species. The next beds, in a de- 

 scending order, are obscured, in the interior, by the diluvium 

 which is generally spread over the surface of these valleys, but 

 are exposed on other places on the coast ; and they consist of 

 shale, with the fossils of the Oxford clay, overlying a limestone 

 resembling cornbrash and forest-marble, the latter associated 

 with calciferous grit. To these succeed other sandstones, and 

 shales containing belemnites and ammonites, through which 

 the shaft of the present coal-pit is sunk, to the depth of near 

 eighty yards below the level of the river Brora. The principal 

 bed of coal is three feet five inches in thickness, and the roof is 

 a sandy calcareous mixture of fossil shells, and a compressed as- 

 semblage of leaves and stems of plants, passing into the coal it- 



