296 Tlie Americmi Geologist. May, i898 
Lnndy, Newberry, Iroquois, Hudson-Champlain, and St. 
Lawrence, in the compound hydrographic basin of the present 
great lakes tributary to the river St. Lawrence. For the 
United States and Canada, Chambedin has well observed that 
if an attempt were made to enumerate all our glacial lakes, 
large and small, temporarily formed in valleys and basins slop- 
ing toward the retreating border of the ice-sheet, they would 
be counted "not by scores and hundreds, but by thousands." 
July 1st and 2nd of last summer, two very clear and beau- 
tiful days, were given to my examination of Glens Roy, Glo}- 
Spean, and their tributaries, and the cols over which the 
glacial lakes outflowed. Coming by railway from Fort 
William to Roy Bridge station, I thence walked up Glen Roy, 
and up the Turret and Chomhlain valleys, its northwestern 
tributaries, to the Gloy col; slept in a shepherd's cottage; 
walked back to Glen Glaster, over its col to the Spean, onward 
to loch Treig, and back to Tulloch, (formerly Inverlair ) sta- 
tion; and thence returned by railway to Fort William. Ex- 
cepting the westward and late extension of lake Roy down the 
Spean valley below the junction of Glen Roy, all the district 
thus observed lies on the Glen Roy sheet (63) of the Ordnance 
Survey of Scotland, which has the scale of a mile to an inch 
and is contoured for each 250 feet of altitude. This sheet, in 
accordance with the request of Milne-Home, includes detailed 
mapping of the Parallel Roads. 
Lake Roy began with outflow northeastward from the 
head of Glen Roy into tlie river Spey, whose valley was earlier 
uncovered from the receding ice-sheet. The col between the 
Roy and Spey is 1,151 feet above the sea, this being the sur- 
face of a shallow peaty swamp, which, filled a few feet a]:)Ove 
the old river bed of outflow, occupies the water divide in the 
continuous, mountain-walled valley. Along the distance of 
about a mile thence to loch Spey the pass has a descent of only 
nine feet. The highest wave-worn shore of lake Roy, record- 
ing its extension while outflowing at this col, has an altitude 
of 1,150 feet, very nearly, the upper and lower limits of the 
perceptible wave erosion being, according to the Ordnance 
Survey, at 1,155 ^^^1 1,144 ^^eet. The lake at this level attained, 
with the recession of the ice-sheet, a length of nine or ten 
miles, to the north side of Bohuntine hill and Glen Glaster, 
