348 Proceedings of the Royal Physical Society. 



south-east of tlie fault, which is quite in keeping with the 

 rest of the evidence in favour of an ice movement from the 

 south-east throughout the Caithness plain. 



Mr Dick noted a large granite boulder on the hill-side 

 above East Murkle, near Castletown, a similar one at the 

 head of Weston Loch, and two of the same material round 

 the same loch. He has also recorded the occurrence of a 

 conglomerate boulder near the Slater's Obelisk at Holborn 

 Head. Mr C. W. Peach observed blocks of the Sarclet con- 

 glomerate near Weydale, south-east of Thurso. 



West of Eeay numerous blocs iierches occur on the moraine 

 heaps, consisting of granite and granitic breccia, and at Dal- 

 nawillan, in Strathmore, blocks of metamorphic rocks also 

 occur on the mounds. 



Conclusion. 



We must now consider the evidence which has been 

 adduced in the foregoing pages with the view of determining 

 the probable physical conditions which prevailed during the 

 formation of the various superficial deposits in Caithness. 

 We have endeavoured to show that across the plain there is 

 one prevalent system of ice-markings running south-east and 

 north-west, which, from the appearances presented by the 

 striated surfaces near Latheronwheel, the Old Man of Wick, 

 and Brough, seem to have been produced by ice moving from 

 the south-east. This conclusion receives additional support 

 from the fact that, as we proceed from the Ord to Eeay along 

 the tract lying between the county boundary and the inland 

 limit of the shelly drift, the striae point E., E.N.E., N.KE., 

 N., and eventually swing round to the N.W. The traverses 

 we made across this tract place beyond doubt that the local 

 ice, radiating from the hilly ground to the west, moved 

 outwards towards the Caithness plain, but having there 

 met a powerful opposing ice-current, it was compelled to 

 change its course and turn round in the direction of the 

 Atlantic. 



That such was really the case is confirmed by an analysis 

 of the evidence supplied by the boulder clay. There are two 



