298 The American Geologist. May, iti98 
hight of 848 feet, being now cut probably several feet below 
its level during the existence of the glacial lake. Shore 
erosion making the lowest Parallel J^oad during this time of 
latest and greatest extension of lake Roy was limited between 
862 and 850 feet. The lake held nearly the level of 855 feet, 
being 36 feet above loch Laggan, and having a maxinnun 
depth of about 550 feet at its most southwestern part, in the 
Spean valley about two miles below, Roy Bridge. The length 
of lake Roy in its latest stage, while outflowing beyond loch 
Laggan, exceeded twenty miles in the Spean valley with a 
width of about a half mile easterly and nearly two miles at the 
west. It reached up Glen Roy about ten miles, terminating 
three miles below its col. 
The three principal I^arallel Roads, approximately at 1,150 
feet, 1,170 feet, and 855 feet above the sea, which were the 
shores of lake Roy in its stages of these different outlets, are 
of nearly equal development. They are very narrow beaches 
cut by the waves in the now grassy and heathery drift which 
thinly overspreads the rocky mountain sides, and are best 
seen from some considerable distance by the eye following 
their level lines of brighter green than the general slopes. 
Prof. Henry D. Rogers, after his visit to Glen Roy nearly 
forty years ago, wrote of its Roads: "Seen in profile, as when 
looked at horizontally, they resemble so many artificial hill- 
side cuttings, the back of each terrace lying within the general 
profile of the mountain slope, while the front or outer edge is 
protuberant beyond it." Jamieson says: "Each of the Paral- 
lel Roads consists of a sort of terrace or shelf, generally from 
40 to 70 feet broad, and sloping towards the middle of the glen 
at angles varying from 5^ to 30°.'' 
The best point for obtaining an extensive and impressive 
view of these shore lines from the Glen Roy highway is on the' 
small marginal moraine east of Bohuntine hill, looking thence 
up the glen. Good photographs of this view are for sale at 
Fort William. Much depends on having favorable light and 
clear air for seeing these delicate shore marks most satisfac- 
torily. Their small, though very well defined development, 
when compared with the shore erosion and beach deposits of 
the glacial lake Agassiz and with the modern great lakes of the 
St. Lawrence, seems to me to betoken only a short duration 
