322 Notices of Memoirs — Prof. J. Presticich — 



glacial deposits of Scotland had been a subject of especial investiga- 

 tion, to conclude that the extension of these two glaciers took place 

 during the second cold period, which he thinks was of little less 

 intensity than the first, and that, while the glacier from Glen Arkaig 

 blocked up Glen Gluoy, the glacier from Glen Treig formed a barrier 

 to Glen Eoy. He observes, " Grant, then, these two ice-streams, 

 one in the Great Caledonian Valley and the other at Glen Treig, and 

 the problem of the Parallel Eoads can be solved, provided we allow 

 that glaciers have the power to dam such deep bodies of water as 

 must have occupied Glen Gluoy and Glen Eoy." 



Mr. Jamieson, in support of this view, adduces the extensive 

 glaciation apparent at the entrance both of Glen Arkaig and of Glen 

 Treig, and shows that near the entrance of Glen Gluoy there are ice 

 strise, pointing W. 5° N., or in the direction that a glacier coming 

 from Glen Arkaig would take, and that, in the Spean Valley, opposite 

 Glen Treig, the ice strias are transverse to the valley, or in the direc- 

 tion of the axis of Loch Treig, while on either side they point 

 respectively up and down Glen Spean. He infers, consequently, 

 that the central portion of the glacier ascended the opposite hill to 

 the Col of Glen Glaster, while one branch passed down the valley 

 blocking Glen Eoy, and another branch travelled up the valley east- 

 ward to the Pass of Makoul, and thence into the valley of the Spey. 



The "roads" were, he considers, formed by long-continued shore 

 action at each successive level of the lake, that level being determined 

 by the height of the cols over which the lake waters escaped. In 

 proof of the long duration of the lakes, Mr. Jamieson refers to the 

 great extent of the " roads," and the large size of the mounds 

 at the junction of Glen Turret and Glen Eoy, and of that at the 

 entrance of the Gulban in Glen Spean, which mounds he considers to 

 be deltas formed by the respective streams flowing into the old lakes. 



The author passed in review the opinions of Mr. Milne-Home, 

 Prof. Nicol, Sir John Lubbock, Macculloch, Chambers, and other 

 geologists, and whilst objecting to the hypothesis advanced by Mr. 

 Jamieson, he considers that that theory affords the most satisfactory 

 solution of the problem, only that he would suggest a different 

 interpretation in explanation of the phenomena. 



Dismissing the hypothesis of local glaciers of the second period of 

 glaciation, the author falls back upon the original idea of Agassiz 

 with the development acquired by more recent research, and assigns 

 the Lochaber lakes to the close of the first period of great glaciation. 

 He considers the phenomena are due to the peculiar physiographical 

 conditions of the district, and shows that, owing to the configuration 

 of the country, the drainage of the Ben Nevis range, instead of flowing 

 off from the centre to two or more sides, is diverted to the north side 

 only, because the two streams which receive the southern drainage, 

 not only of Ben Nevis, but also part of that of the range of hills to 

 the south of Ben Nevis, after flowing respectively east and west, 

 turn nothward and debouch e — one through Glen Treig and the 

 other through Glen Nevis, into the lower part of the Spean Valley 

 and the Great Glen near Fort William. These conditions, which 



