iSOO.] JAMIESON- — CAITHNESS. 269 



covering the grey flags is of a reddish brown colour. On the other 

 hand, the dark-grey mud stretches south-eastward, past Lybster, into 

 the bed of the water of Dunbeath, and lies in heavy masses even in the 

 south branch of that stream. I also traced it to the mouth of Berrie- 

 dale water, where it mingles with the reddish-brown drift that pre- 

 vails from there to the Ord ; but further up the Berriedale Glen to 

 the base of the Scarabin hills the colour is reddish brown. The dis- 

 tribution of the dark-grey mud therefore harmonizes with the suppo- 

 sition that the transport had been from the north-west ; and a move- 

 ment of ice from north-west to south-east across Caithness is totally 

 at variance with the notion of the scratches having been caused by 

 glacier-action proceeding from the interior of the country towards 

 the present coast. 



I have already mentioned that the stones imbedded in the drift of 

 Caithness very often show the glacial striae. A\Tien examining the 

 sections along the Haster Burn, in company with Mr. Joseph An- 

 derson, I remarked that the strise on the imbedded fragments gene- 

 rally agreed in direction with those on the rock beneath. The 

 scratches on the boulders, as usual, run lengthways along the stones 

 when they are of an elongated form ; and the position of these stones, 

 as they lie imbedded in the drift, is, as a rule, such that their longer 

 axes point in the same direction as do the scratches on the solid rock 

 beneath, showing that the same agency that scored the rocks also 

 ground and pushed along the drift. Interspersed amongst these 

 ice-worn stones were many fragments of shells — themselves also 

 scratched — and some univalves almost entire. 



This coincidence of direction between the scratches on the stones 

 and those on the subjacent rock I also observed in the section along 

 the Milton Burn ; and I am inclined to think it is a characteristic 

 feature, and will be found of general occurrence. In my paper " On 

 the last Geological changes in Scotland," I have described it as a 

 feature of the boulder-earth or glacial-mud which lies beneath the 

 marine beds in the midland region of Scotland. The appearance of 

 the drift along the Haster Burn and in many other places in Caith- 

 ness is, in fact, precisely the same as that of the Old Boulder-clay 

 of the rest of Scotland, except that it is charged with remains of 

 sea-shells and other marine organisms*. Mr. Anderson told me that 



* The glacial drift of Caithness is particularly interesting as an example of a 

 boulder-clay which, in its mode of accumulation and ice-scratched debris, very 

 much resembles that unstratified stony mud which occurs underneath glaciers — 

 the ' moraine profonde ' as some have called it. But the presence of marine or- 

 ganisms, and the direction of the glacial strise, which indicate a movement of ice 

 from the north-west, where there is now nothing but open sea for an immense 

 distance, together with the absence of moraines, are all suggestive of marine 

 conditions having prevailed during the deposition of the Caithness drift. It 

 would therefore seem that sea-borne ice can in some places accumulate a mass of 

 imstratified stony mud so like that which is found underneath a glacier as to be 

 im distinguishable from it, except by containing remains of sea-animals. The 

 scratched boulders used to be looked upon by some as a certain test of glacier- 

 action. " Ces cailloux," says Ch. Martins, " sont, pour ainsi dire, le fosdle carac- 

 ieristique de la presence d'anciens glaciers." — Bull. Geol. Soc. of France, 2 ser. 

 iv. 1191, 1847. In the Caithness drift, however, not only the stones, but the 

 very sea-shells are glacially scratched, a circumstance which I have also observed 

 in some of the glacial marine beds cf Aberdeenshire. 



