398 Proceedings of the Eoyal Physical Society. 



all the other localities mentioned, in the hard clay itself. 

 The Burn of Strath, to beyond the " Crowner's Garden," is 

 equally rich in clay and organisms. In one very small spot 

 beyond the last-named place, I got many nice specimens of 

 3felobesia, some of them very little rubbed. Can this be an 

 old sea bottom ? I regret that I was never able to get there 

 again when the river was low, to work this out. The Burn 

 of Watten deserves a good search. - The high cliffs over 

 Scrabster are thickly capped with clay, and the upper face 

 of the rock on which it rests is smoothly polished and deeply 

 grooved ; such is the case with the whole of the rocks on 

 which the clay is deposited. Hence to Thurso, and all along 

 the river to far inland, the clay is abundant. At "Geize," 

 old John Busby, in 1802, " found blue clay-marl in great 

 plenty intermixed with marine shells," and also at Dale- 

 more. What a pity it is that this interesting discovery was 

 lost sight of so long ! 



From Thurso, all along the side of the Pentland Firth to 

 Mey Castle, Canisbay, John o' Groats, Duncansbay Head, 

 thence to the Burn of Freswick, Keiss, and to Wick, thence 

 to Lybster, Forse, Latheron, Latheron Wheel, Dunbeath, 

 &c, in all these places, and many more localities, I have 

 found organisms in greater or less quantities. Although 

 the clay is not uniform in texture, being finer or coarser, in 

 some places almost free from stones, and these of small size, 

 in others — even at short distances apart — it is full of stones, 

 many of large size, and in all places polished and grooved 

 ones are far from rare. The clay itself is always hard and 

 rough to the touch. For the present, although considered 

 objectionable by many, it will be well to retain the name of 

 boulder clay for the deposit. I do not object to its being 

 called glacial, for it evidently was in the first instance 

 derived from, glaciers, but forced to sea and deposited by 

 icebergs stranded on the Caithness shores. These icebergs, 

 when first launched into the sea by the ice-streams from 

 the glaciers, picked up some of the sea-bottom, with its 

 organisms ; and when on their voyages, wherever they 

 touched, they added to their burthen by picking up more 



