70 HiS'TORr of the sociE-rr. 



ced in the northern pare of the ifland, have their fides covered 

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

 lliore, fucceed fccondary ftrata of grit, limeftone, and even coal. 

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

 mining the juncflion 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 north- 

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

 fpecimen of fome hundred weight, confifting 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. In 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 fofTil which he had not before met with in its native 

 place ; he found other interefting fubjedls of obfervation ; fo 

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

 to fay that he had no wdiere found his expedlations fo much ex- 

 ceeded, as in the grand and inftrudive appearances with which 

 nature has adorned this little ifland. j 



IWr John Clerk, the fon of his friend Mr Clerk of Eldemi, 

 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 manufcrlpt. 



The leaft complete of the obfervations at Arran was that 

 of the juniflion of the primitive with the fecondary ftrata, 

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

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

 though it forms a line circuoifcribiijg the bafes, of all primitive 



..V- countries, 



