﻿1861.] 



MTJECHISON AND GEIKIE HIGHLANDS. 



227 



At Dalrelzian, limestone is again quarried. This band has a 

 westerly dip at the quarry; but its general range is from S.~W. to 

 N.E., as it occurs in Strath Ardle, south of Kirkmichael, and crosses 

 by the southern flank of Mount Blah- into Glen Isla. It is suc- 

 ceeded by gnarled schists, and these again at the Bridge of Cally 

 by slates, which have a decided S.E. dip at a high angle. In a short 

 distance, however, the slates take a north-west dip, as they do at 

 Birnam ; and at Kattray, a little north of Blairgowrie, they are 

 overlain by the conglomerate of the Old Bed Sandstone. 



Eastern Flanks of the Grampians. — It was a special object of one 

 of us in a former year to re-examine the schistose rocks on the 

 eastern flanks of the Grampians in Kincardineshire and Forfarshire. 

 This was done in two traverses on different parallels in 1827 and in 

 1859 ; and in both of these the succession was found to be similar. 

 In fact, a perfect conformity between argillaceous schists with some 

 limestone, and certain micaceous schists lying nearest to the interior 

 of the chain, was found to prevail. Numerous bosses of porphyry, 

 not laid down on any map, were also observed ; and around these 

 granitic, syenitic, or other amorphous rocks, the highly broken strata 

 assumed a gneissic character. 



Any one who is acquainted with those localities, i. e. the valleys 

 of the Bervie Glen, west of Laurence Kirk, of the Forth Esk, the 

 Prosser, and South Esk, and will now read our descriptions of the 

 superior schistose and slaty rocks with limestone in the south of 

 I slay, cannot doubt that on the east flank of the Grampians we have 

 a repetition of the upper portion of the same great series, the dif- 

 ferent members of which we have traced in vast undulations from 

 N.W. to S.E. In fact, the detailed and faithful description of the 

 transverse valley of the North Esk by Colonel Imrie, which was 

 read in the year 1804 *, may be still referred to, after so long an 

 interval, as being in itself a full and copious illustration of our 

 upper series ; though, when that paper was written, the author, as 

 well as most of his contemporaries, believed that all such Grampian 

 primary schistose strata had been accumulated at a period long an- 

 terior to the existence of life upon the surface of the globe. 



In this section we also meet with the valuable proof that all the 

 so-called slates were in truth layers of subaqueous deposit, inasmuch 

 as they alternate over and over with what Colonel Imrie called 

 his " aggregate rock," or, in other words, strata of broken mate- 

 rials accumulated in ancient seas. As this section was examined 

 on foot by one of us in company with Professor Sedgwick in 1827 

 and found to be quite correct, we now see how completely the facts 

 accord with all our subsequent observations on other flanks of the 

 Grampians. 



"Whilst on this occasion we are unprepared to enter into a detailed 

 description of the Grampians, we feel assured, from examination of 

 the flanks of these mountains on many points of the compass, that 

 the strata which there exist belong, on the whole, to the upper 

 members of the crystalline stratified rocks of the Highlands, with 

 * Trans. Eoy. Soc. Edinburgh, vol. vi. p. 1. 



