165 



ently of examining the two great Old Red outliers of the Ben Gream, we merely 

 looked at the rocks in our wa}', which were chiefly granite, with that gneiss 

 which we consider as newer gneiss. 



But we ought to have halted for some days at the very comfortable isolated 

 iim of Achintoul, whence we should have pushed forward and entered to the 

 sources of the Berriedale series and the western flanks of the "Scarabein." 



I have gone along their immediate western flanks and found highly inclined 

 gneiss and granite, and the same extend southward and west of there towards 

 Kildonan. 



All, however, seemed so broken and chaotic that I could not venture to 

 identify the quartz rock of the Scarabein with that of the West coast. 



For what so likely as to have another band of altered sandstone higher in the 

 series ? 



If, on the other hand, it be possible through your labours, to determine the 

 existence of a trough — then I believe that the quartz rocks near Portsoy on the 

 East coast of Aberdeen, with the limestones and serpentines, will fit into the 

 same category. I rejoice at the prospect of your clearing up this most im- 

 portant point. But I must entreat you not to do it in a mere skirmish. 

 Abandon eveiything else for this fundamental question, and if you do go to 

 Achintoul, pray walk not by the high road, but mountaineer along the great 

 granitoid band to the N.N.E. of the Achintoul iim, which separates Caithness 

 from Sutherland. 



No one has done this. 



Nor has any geologist examined the inland tract between Strathnane and 

 Strath Helladale. 



To do that you must live a night or two with the shepherds, but it would, 

 / am sure, well repay you ; and you may there find great undulations and even 

 reversions of the strata. 



If you decide on such a campaign I will again send you the Duke's map of 

 Sutherland, and any notes of mine bearing on the Scarabein. The latter 

 mountains are best examined in detail from the inn at Berriedale on their 

 eastern slope. 



I thought I detected the most obvious proofs of the gradual metamorphism of 

 sandstones, flagstones, and schists, little altered in the east, into the very pure 

 quartz rock of these mountains at their summits. 



The Rev. Mr. Joass, of Edderton, Ross (W. of Tain), has discovered a fine 

 preserve of the Caithness fish in his parish. They are all promised to me. 



If you go there you will see how closely the yellow sandstone of Port 

 Mahannah and Tarbet Ness overlie these fish deposits. 



Yours sincerely, 



R. I. MURCHISON. 



