Erratics.

Over the Caithness plain occasional boulders have been observed resting on the boulder clay, or partly buried in that deposit, which bear unmistakably the impress of glacial action on their smoothed and striated sides. They cannot be said to be numerous; still a few have been chronicled by Mr Dick and Mr C. W. Peach in their rambles, while we met with several examples during our traverses. The smaller boulders have been removed from the fields in the course of the reclamation of the land, and have been used for building dykes. At Greenvale a boulder of the Sarclet conglomerate was noted by us, and erratics of hornblendic granite. East of St John's Loch boulders of granite were also observed. Along the road from Greenvale to Ham various blocks of foreign rocks occur, which have been borne off the fields, amongst which may be mentioned grey and pink granite, quartzite, grey micaceous gneiss, red sandstone like the beds at Ham, and conglomerate. No boulders of the Upper Old Bed Sandstones, which form the tract already referred to between Brough and Dunnet Bay, were observed to the page 34 south-east of the 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. Teach observed blocks of the Sarclet conglomerate near Weydale, south-east of Thurso.

West of Eeay numerous blocs pcrchés occur on the moraine heaps, consisting of granite and granitic breccia, and at Dalnawillan, in Strathmore, blocks of metamorphic rocks also occur on the mounds.