Messrs Peach and Home on the Glaciation of Caithness. 331 



clay, containing an admixture of rocks of local origin, with 

 a large proportion of blocks wliich are foreign to the district ; 

 (2.) a reddish or brown boulder clay, containing no shells, 

 and including stones derived from the area traversed by the 

 local ice-flow. A line drawn from Shebster midway between 

 Eeay and the Forss Water, south-eastwards by Scotscalder 

 Station and Strathmore Lodge to Dunbeath, marks approxi- 

 mately the inland limit of the dark grey boulder clay charged 

 with marine shells. The coast-line from Dunbeath to Dun- 

 cansbay Head, and thence to near Eeay, forms the boundary 

 line on the east and north. Over the whole of this 

 triangular- shaped area, measuring about 300 square miles, 

 the shelly boulder clay is distributed in irregular sheets ; 

 and when we consider the remarkable features presented 

 by this deposit and the extent of ground which it covers, 

 there is little wonder that its origin has given rise to 

 considerable discussion. Throughout the area occupied by 

 the shelly drift, the striations have a general north-westerly 

 trend, as already indicated ; and in a subsequent paragraph 

 we shall describe certain facts connected with the dispersal 

 of the stones in this deposit, which indicate that the ice-flow 

 must have been from the North Sea towards the Atlantic. 

 The reddish or brown boulder clay, containing no marine 

 shells, lies to the west of the line which marks the inland 

 limit of the shelly drift. We shall first describe the moraine 

 jprofonde produced by the local ice-flow. 



On the shore, between the Ord and Berriedale, the deposit 

 consists of a reddish-brown gritty clay, with well-striated 

 stones composed of rocks belonging to the immediate neigh- 

 bourhood. Amongst these may be mentioned pink granite, 

 gneiss, quartzite, granitic breccia, red flags, grits, and shales, 

 all of which occur in the vicinity. No shells were observed 

 in this deposit, nor any of the secondary rocks which are so 

 prevalent in the shelly drift. As already described, the stria3 

 along this part of the coast point seawards, and the deposit 

 has evidently been produced by ice which radiated from the 

 adjoining high ground. But to the north of Berriedale and 

 onwards to Dunbeath, where the striae begin to bend inland, 

 the boulder clay completely changes its character. The colour 



