Messrs Peach and Home on the Glaciation of Caithness. 327 



evidence is obtained. About two miles south-west of Eeay, 

 on the south slope of Ben Eah (795 feet), less than a mile 

 from the county boundary, there are fine examples of glacial 

 abrasion to be seen. The two peaks on this hill are composed 

 of outliers of coarse granitic breccia resting on fine white 

 sandstones, which are beautifully polished on the intervening 

 col and on the south slope. Indeed, the striations are as 

 fresh as if the ice had but recently passed away, and they 

 leave no room for doubt as to the direction from which the 

 ice came. The instances noted by us point N. 10° E., N., 

 and K 10° W. ; and they are situated to the west of the 

 limits of the shelly boulder clay. It is evident, therefore, 

 that the local ice must have been powerful enough to over- 

 ride hills of considerable elevation near the sea-level. 

 Descending the slope to the burn of Isauld the strise swing 

 round to the north-west as already indicated. 



From the evidence now adduced it is clear that these two 

 diverging systems point to the existence of two opposing 

 streams of ice. From the hilly ground along the county, 

 boundary and the heights in the east of Sutherlandshire the 

 local ice flowed E.N.E. and N.N.E. towards the Caithness 

 plain, while near the Ord and at Eeay it flowed into the sea. 

 But along the line indicated by the inland margin of the 

 shelly drift, the local ice was compelled to veer round to the 

 N., and eventually to the N.W. in harmony with the general 

 movement all over the great plain. The " cross-hatching " 

 met with along this line indicates a sustained conflict 

 between the opposing streams, which resulted in favour of 

 the north-westerly ice-flow. On both sides of this line the 

 boulder clay is of two distinct types, as will be presently 

 described. Occasionally there is a commingling of the 

 material belonging to the rival ice-streams, but in general the 

 features are totally different. Indeed, the phenomena now 

 referred to are quite analogous to those met with in the 

 central valley of Scotland, so well described by our friend 

 and colleague Dr James Geikie. In this latter case, the 

 great ice-streams from the Highlands and Southern Uplands 

 coalesced in the midland valley, producing similar " cross- 

 hatching " and the same commingling of the moraine fvofonde 



