622 



SCOTLAND. 



Statistics. It abounds in the southern promontory of Shetland, 

 ^-'V'**-' and is also found scattered in many places to the 

 Geology, northward, and in many of the smaller islands. The 

 greatest tract here is that which reaches from Sum- 

 burgh-head northwards to Scalloway and beyond it. 

 For the others we shall refer to the accurate documents 

 already pointed out. In the Western islands there is 

 a slender tract of this rock on the eastern shore of 

 North Uist, and the adjoining spots ; but the only con- 

 spicuous tract is that which accompanies the quartz 

 rock already described, of Jura, and the remainder of 

 that chain. This was formerly noticed in a commer- 

 cial view. The principal mass occupies the small 

 islands there described, with all those smaller ones 

 which lie in the strait that separates these from the 

 chain of Jura. On this side it skirts the eastern shore, 

 even to the extremity of Isla, where it might also be 

 wrought ; and it moreover appears on the western side 

 of the latter island, in various and extensive strata. 



In Arran it accompanies the granite ; and in Bute 

 and Inch Marnoch, where it is also wrought, it must 

 be conceived to 'belong to that extensive range which 

 traverses Scotland ; and which we may now describe, 

 as it is impossible to pursue any useful order in this 

 description. This tract is of various breadth, but sel- 

 dom exceeds a mile or two ; and it extends in a tolera- 

 bly straight line to the east shore, passing through the 

 points formerly indicated as quarries. This is not, 

 however, an entire mass of clay slate, but consists of 

 various schistose rocks, among which thwt substance 

 seldom occupies more than a third or fourth part. 

 The whole belt is defined with tolerable accuracy on 

 both sides ; though, without a coloured map, we could 

 not lay down, nor even approximate to its limits. It 

 remains for those to whom its course and extent are 

 thus pointed out, to render it of far more value than it 

 has yet been, by opening quarries in many other 

 places, where a populous and adjoining country would 

 insure a regular and sufficient demand. 



On the west shore there is a small portion of clay 

 slate near the Crinan canal, which, geologically, pos- 

 sesses a certain connection with that of the slate islands 

 of this coast, and which might be wrought were there 

 any demand ; but we need not point out any more of 

 these trifling strata till we reach that at Balahulish. 

 The extent of this rock is, in this vicinity, more consi- 

 derable than is apprehended, but as the convenience of 

 the Glenco quarries supersedes any other, it is not 

 likely to be ever more widely wrought. 



The very small quantity of slate which occurs occa- 

 sionally on the western shore, as near Loch Carron and 

 elsewhere, commonly interstratified with gneiss, renders 

 k of no value; and, as a piece of geological topography, 

 it is impossible to define them : but among these we 

 must notice one small portion in Loch Eribol, which 

 might probably be turned to the advantage, at least of 

 the surrounding country, where the poor cottagers are 

 often much troubled to find the means of covering their 

 houses. On the eastern side of Sutherland there is also 

 some slate, near the quartz rock ; but no attempts have 

 been made to work it. 



Passing the Moray Firth, on this side, we find various 

 beds of slate traversing die country to the south of Cul- 

 len and Banff; and some well-known portions of this 

 appear at Fortsoy, though no attempts have been made 

 to work it. The topography of these scattered portions 

 is here inexplicable, but we soon arrive at a much more 

 extensive mass, which stretches eastward from Banff, 

 and penetrates a long way south into the interior coun. 



try. This is a tract already worked, and which might ^Statistics. 

 be wrought much more extensively in this rich and **ZTY~~~ 

 populous county, were its existence through so large ( 

 a space suspected. It is now quarried in Fouldan Hill, 

 possibly elsewhere, and its produce is of a very good 

 quality. To geological science abstractedly, some of 

 its connections are interesting ; but the details would 

 take us out of the rigid path of the present topographi- 

 cal sketch of Scottish geology. 



To omit noticing a few patches and minuter strata 

 of this rock so scattered and so trifling as to be im- 

 practicable in detail, we must now pass suddenly from 

 the north to that immense tract of the same rock which 

 may almost be said to form the south of Scotland. 

 Here again we are lost in attempts to define its boun- 

 daries ; and, as formerly, must trust partly to the ac- 

 count we shall have to give of the sandstone, which 

 forms the chief exception^ 



But of this rock, we must first remark, geologically, 

 that its general characters are very different from that 

 of the clay slate in the northern division, as we partly 

 indicated in treating of the physical geography pf that 

 district. There is here no such regular sequence from 

 granite upwards, nor no superposition of this clay slate 

 to mica slate and gneiss, as so often occurs there. In 

 fact, its real geological connections and positions are 

 as yet very obscure; but in this it partakes with 

 Wales, the Isle of Man, Cornwall, and Cumberland, 

 which, in all important particulars, it resembles. It is 

 probable that it must be esteemed, like those, to follow 

 immediately on granite, with few or scanty portions of 

 other rocks interposed ; and that there is thus but a 

 brief and imperfect series between the lowest of the 

 primary and the lowest of the secondary rocks. 



In its mineral character also, it somewhat differs, as 

 it does in the accuracy of its stratification and of its 

 lamination, or fissile tendency. Hence it is difficult to 

 discover and pursue the stratification ; and as the la- 

 minar tendency is equally rare, or irregular, or obscure, 

 it seldom is capable of affording roofing slate. Yet we 

 must observe that it has not been sufficiently examined 

 for this purpose, and is indeed, in most places, scarcely 

 suspected of being the very substance from which slate 

 is generally procured. , With respect to its quality or 

 texture, the coarser kinds, formed of fragments more 

 or less minute, prevail very much ; yet these are sus- 

 ceptible of being wrought for slate, as they actually 

 are in Cumberland ; while even among the coarsest 

 rocks, beds of a perfectly fine quality are often inter- 

 posed. 



To define this great tract of clay slate to the north- 

 ward, it is necessary to commence with St. Abb's head, 

 and to pursue the course of the Lammermuir hills, still 

 continuing to skirt the mountains till we reach the sea 

 coast near Ayr. Hence westward, eastward, and south- 

 ward, Scotland alone is its boundary, if we except the 

 intrusions of the northern coalfield, the red sand stone, 

 of both kinds, beneath the coal in one case and above 

 it in the other which enters near Berwick from Eng- 

 land, as well as into Roxburghshire along the course of 

 the Es,k, at Jedburgh, and into Dumfries-shire or Gallo- 

 way ; tracts which we find ourselves unable to define 

 in words by any species of topographical reference. 



The granite already mentioned is also, of course, 

 excepted. The general elevations and characters of 

 this country were formerly given, and we may thus 

 terminate the history of this important rock in Scotland. 



Among the primary rocks, besides limestone, it re- 

 mains to notice one or two which occur in very small 



