324 Notices of Memoirs — Prof. J. Presticich — 



consist of a light grey argillaceous unstratified matrix with angular 

 fragments of the local rocks capped by stratified gravel. The mass 

 rises nearly to the level of the lower parallel road. 



The author next discussed the height of the land in relation 

 to the sea at the period of the great glaciation, and he sees reason 

 to conclude that the land then stood at not less than from 1000 

 to 1500 feet higher than at present, so that the Irish Channel was 

 then above the sea-level, and land extended a considerable distance 

 westward from the present coast of Scotland. 



This was followed by a submergence of not less than 1200 to 

 1500 feet in central and northern England, Wales, and Ireland, and 

 of 600 feet in the southern part of Scotland, as proved by the 

 occurrence of marine shells at those heights. 



The influence of difference in level upon climate was next dis- 

 cussed, and Its effect was stated to be, probably, not less than from 

 12° to 15° F., which is about equivalent to the difference of climate 

 between Paris and St. Petersburg. 



It is well known that the Parallel Eoads are terraces composed of 

 perfectly angular fragments of the local rocks with a few rounded 

 pebbles, both local and foreign to the district. The former show an 

 entire absence of any prolonged beach wear. The wear of the latter 

 is due to other causes. There is also an entire absence of any notch 

 or cliff line such as would be due to the wearing back of a shore 

 line, and of any projecting ledge such as would result from the 

 throwing forward of the shore debris. The slope of the hills above 

 and below the " roads " varies from 25° to 40°, and the inclination 

 with the horizon of the " roads " themselves, which are from 50 to 

 70 feet wide, varies within the limits of from 5° to 30°. 



Although therefore the " roads " indicate a line of water-level, 

 there is nothing in their form or structure to show that they have 

 been formed by the long-continued action of lake waters on a shore 

 line. To what then are they to be ascribed? 



The first or highest "roads" is confined to Glen Gluoy, the second 

 and third to Glen Roy, and the fourth or lowest to Glen Eoy and 

 Glen Spean. What the conditions were immediately antecedent to the 

 formation of the first, second, and fourth road, is not shown ; but in the 

 case of the third road, the conditions preceding its formation are to 

 be traced uninterruptedly from the conclusion of No. 2 " Road." 

 When the lake stood at the level of " Road " No. 2, its waters escaped 

 by the col leading to Glen Spey, while when they stood at the level 

 of No. 3 " Road," they escaped by the Glen Glaster Col. Now as 

 there is a difference of 76 feet between the height of the two cols, it 

 is evident that a barrier must have existed on the latter col during 

 the time the lake stood at the higher level. Whether the barrier was 

 detrital or ice-formed is immaterial for the argument. In both cases, 

 either by gradual weathering or melting, the time would come when 

 the barrier would be lowered in some place to the level of the lake. 



Now, it is well known to engineers that a breach once established 

 in a detrital barrier becomes so rapidly enlarged that, if not at once 

 stopped, nothing can stay the rapid destruction of the barrier, as in 



