SCOTLAND. 



quantities, and which are rather objects of geological 

 Curiosity than of gi-m-rai or ecotio:: 



The first of tlii-M: is serpentine, sparingly dispersed 

 everywhere, though found in many | ' 'ue of 



tlie most remarkable, and the most extensive tracts of 

 , k, ocnir* in tin- Shetland islands, where, how- 

 it is nearly limited to the two norther; 

 Unst and Fetlar. It here forms a body of considerable 

 extent, stratified among the other primary rocks, and 

 accompanied by diallage rock. It forms lofty and bold 

 broken cliffs, and rises into hills considerable for these 

 islands. It is chiefly remarkable here for the minerals 

 which it contains, of which chromate of iron is the 

 most conspicuous ; a substance which might have been 

 of great value in the arts of dyeing and colour-making, 

 had not the market been more easily supplied from 

 America. It also produces two rare minerals, the hy- 

 drate of magnesia and oxide of chrome, of wliich the 

 latter has hitherto been found nowhere else. As far 

 as has yet been observed, it contains no ornamental 

 portions, being generally of a uniform dull green; but 

 it is very possible that these may exist in it. 



As the diallage rock is known only here in all Scot- 

 land, we shall now mention it, that we may not have to 

 recur to Shetland again immediately. This rare sub- 

 stance is intimately associated with the serpentine, 

 forming the whole of the small island Balta, and parts 

 of Unst and Wya, and being found also in very small 

 portions on the mainland of Shetland. 



In the Western Islands, serpentine occurs in the 

 island of Scalpa, the seat of the lighthouse on the east 

 coast, and also on the neighbouring shore of Harris. 

 Otherwise, it does not appear to have been observed in 

 the islands, if we except quantities exceedingly trifling 

 in lona and Sky. 



On the west of Sutherland, it occurs in three or four 

 places, dispersedly, and in very small quantities, inter- 

 htratified with gneiss; and here also, as in Scalpa, it is 

 without beauty. That of Portsoy is the next conspicu- 

 ous mass known ; and it is familiar from having been 

 long, though scantily wrought. In early times it was 

 exported to France ; and ornamental architecture from 

 it is said to be still existing at Paris. It is not now 

 encouraged ; though, from its very great variety and 

 beauty, and from the facility of quarrying and ship- 

 ment, it might be rendered profitable, as well as orna- 

 mental, were it to obtain a fashion. Geologically 

 speaking, it seems to be interstratified with the slate, 

 gneiss, and quartz rock of the same locality ; but it is 

 not easy to ascertain this satisfactorily, as it appears in 

 itself fo be but an irregular mass. 



In Aberdeenshire there are numerous independent 

 masses of serpentine scattered about the country; but 

 the greatest number of thejn are very small ; and 

 none are extensive. They are, in some cases, singular- 

 ly connected with granite, and at others appear to be 

 short strata, including schistose rocks. The masses 

 near Kildrummie and Glen Kindie seem the most ex- 

 tensive, and they afford considerable quantities of as> 

 bestos. Serpentine also occurs in connexion with trap, 

 and otherwise, on the confines of the mountains of 

 Angus ; and at Clunie in Perthshire it presents the rare 

 and interesting phenomenon of a transition into trap, 

 forming the sides of a vein of that substance. The last 

 mass of this rock which we are acquainted with in 

 Scotland, is found on the west coast, between Girvan 

 and Ballantrae. 



Chlorite schist is so little distinct in general from 

 micaceous schist, that we have not thought it worth 



while hitherto to distinguish the two; but we cannot 



ng out to geologist a singular series < 

 00 the west coast of Ar r> li,hire; although, as 

 the detail* are too minute fur our article, we must re- 

 'lie work on the Western 1. lands formerly nataed. 

 v. bere there ia a somewhat minute description c: 



It reman, to point out the primary limestone . 

 Scotland, w hich are, like tome other rocks, to dispersed. 

 and in biuii minute quantities, that we scarcely know 

 how t. them, but shall, aa usual, rnmnMBd 



with the Shetland Islands. 



vrry nmmrous, though seldom ex. 

 tensive; being interstratified with the oth<-r primary 

 rocks, and found in almost every place. The largest 

 apparent mass in one place is that at Strom new Voej 

 and next in importance are those of Tmgwall, the Out- 

 fckerries, and a few other places, for which it will be 

 best to refer, as usual, to Dr. Hibbert. The geological 

 appearances are sometimes interesting, particularly in 

 Burra, and in other places where granite occur.- 

 they precisely resemble those of Glen TilL Economi- 

 cally speaking, Shetland has not yet derived the ad. 

 vantages from its limestone, in agriculture, which it 

 might have done ; but that is not to be wondered ar, 

 where this art is so backward, and encumbered with so 

 many political and physical impediments. 



In the Western Islands primary limestones are rare. 

 With exceptions too trifling to name, they are found 

 only in Lismore, Tirey, lona, the GarveJoch isles, and 

 Isla. The marble of Tirey is familiar ; but the work- 

 ing of this quarry has long been abandoned for want 

 of a demand. It is a lump lying in gneiss, and is at* 

 tended by a similar one of a beautifully white marble, 

 often spotted with green, hitherto unnoticed. The 

 white marble of lona is equally well known ; but it has 

 long been exhausted. We already noticed that of the 

 Garveloch isles as a possible branch of commerce ; and 

 need only here add, that it is accompanied by mica 

 slate. We also mentioned that of Lismore at the same 

 time ; but this variety is of no beauty, being blue, and 

 interstratified with clay slate, as are the corresponding 

 strata in Appin. In Isla the limestone forms an ex- 

 tensive tract, and is noted for containing lead mines, 

 which were formerly wrought. 



In examining the limestone of the Mainland, we 

 must commence with Sutherland, as it contains the 

 most extensive tracts of this rock. The westernmost of 

 these is found at Diurness, occupying the bay to a con- 

 siderable extent inland, and forming a small island off 

 its entrance. Though we have here enumerated this 

 with the primary limestones, it is rather our opinion 

 that it belongs to the secondary, and is analogous to 

 the lowest ot these, or to the mountain limestone of 

 English geologists. It contains a subterranean cavern 

 ot some interest, called Smow, giving passage to a river 

 which plunges into it about a mile inland, to re-appear 

 at the sea shore. 



In Loch Eribol there is another tract of the same 

 rock, but of less extent, most conspicuous in a small 

 island at the upper part of this bay. Another of still 

 greater extent, and among the largest in Scotland, is 

 found in the parish of Assynt ; and we have already 

 noticed it as formerly wrought for ornamental marbles. 

 This portion occupies the whole of the valley in which 

 it lies, connected with quartz rock and gneiss like the 

 former ; and the ornamental varieties are a black bitu- 

 minous limestone of a small crystalline grain, varied 

 with red or white calcareous spar. Not very far from 

 this, at Lead Beg, there is a much smaller tract, which 



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