150 



The paper next proceeds to bring forward Proofs of a more Ge- 

 neral Glaciation in Scotland. 



Traces of glacial action in the smoothing and furrowing of rocks, 

 and in the deposit of the appropriate detrital accumulations and 

 blocks, have heretofore been detected in various parts of Scotland. 

 In the southern and eastern skirts of the Highlands, the direction 

 indicated for the agent is southerly and easterly. In the valley of 

 the Firth of Forth, both in the low grounds, and high up the hills 

 on both sides, are phenomena of this kind, with an indication of di- 

 rection from about WSW. Having found a few instances in the 

 north of Argyllshire and parts of Inverness-shire, where the agent 

 appeared to have had a direction from the east, Mr Maclaren and 

 M. Charles Martins had become satisfied that there had been ordi- 

 nary glaciers in 'the group of mountains between the Clyde and 

 Lochaber, and that they had, as usual, radiated outwards. Thus it 

 was held as possible to acco-unt for the whole phenomena which had 

 been observed. 



The author af the present paper has extended his observations to 

 the large Highland district to the northward of the great glen, and 

 particularly to the old red sandstone district of western Ross and 

 Sutherland. He has there found glacially-smoothed rocks, even 

 more abundantly than in the southern region. They occur in many 

 valleys, generally in the line of the valleys, and also on many elevated 

 situations, even to 2000 feet abovfe the level of the sea. In all elevated 

 positions, and in all open regions free of valleys, the line of the stria- 

 tion shews a marked tendency to observe one direction, and that be- 

 tween north-west and south-east. This is alike the case in Mull and in 

 Skye, on Ben-Eay beside Loch Maree in Ross-shire, and on the moun- 

 tains of Cuineag and Canisp in Sutherlandshire, in the wide-spread 

 rocky plains of Lord Reay's country, and on the gentle undulations of 

 Caithness. The white quartz rocks of the Assynt mountains retain the 

 striation over wide areas and with great clearness. It is also remark- 

 able that some of these mountains are of a narrow lengthy form, with 

 the longitudinal axis in the same direction as the striation, while the 

 intermediate hollows, containing the long lakes for which the district 

 is remarkable, observe the same direction. The whole series of the 

 old red sandstone mountains of Ross and Sutherland, extending for 

 fifty mileSy observe a horizontal stratification, so that each separate 

 hill looks like a pile of masonry resting on a gneissic platform. Find- 



