70 HISTORY of the SOCIETY. 



ced in the northern part of the ifland, have their fides covered. 

 with primitive fchiftus of various kinds, to which, on the fea- 

 fhore, fucceed fecondary ftrata of grit, limeftone, and even coal. 

 Here, therefore, Dr Hutton had another opportunity of exa- 

 mining the junction of the granite and fchiftus, and found 

 abundance of the veins of the former penetrating into the latter. 

 In three different places he met with this phenomenon ; in the 

 torrents that defcend from the fouth fide of Goatfield ; in Glen- 

 rofa, on the weft, and in the little river Sannax, on the nonh- 

 ead, of that mountain. From the firft of thefe he brought a 

 fpecimen of fome hundred weight, confiding of a block of 

 fchiftus, which includes a large vein of granite. 



At the northern extremity of the ifland he had likewife a 

 view of the fecondary ftrata lying upon the primary, with their 

 planes at right angles to one another. Tn the great quantity, 

 alfo, of pudding-ftone, containing rounded quartzy gravel, uni- 

 ted by an arenaceous cement ; in the multitude of whinftone 

 dikes, which abound in this ifland ; and in the veins of pitch- 

 ftone, a foffil which he had not before met with in its native 

 place ; he found other interefting fubjects of obfervation ; £6 

 that he returned from this tour highly gratified, and ufed often 

 to fay that he had no where found his expectations fo much ex- 

 ceeded, as in the grand and inftructive appearances with which 

 nature has adorned this little ifland. 



Mr John Clerk, the fon of his friend Mr Clerk of Elden, 

 accompanied him in this excurfion, and made feveral drawings, 

 which, together with a defcription of the ifland drawn up after- 

 wards by Dr Hutton, ftill remain in manufcript. 



The leaft complete of the obfervations at Arran was that 

 of the junction of the primitive with the fecondary ftrata, 

 which is but indiftinctly feen in that ifland, and only at 

 one place. Indeed, the contact of thefe two kinds of rock, 

 though it forms a line circumfcribing the bafes of all primitive 



countries; 



