PROCEEDINGS OF GEOLOGICAL SOCIETIES. 
261 
Lanrcntiiie chain of mountains, on the north sitle of the St. Lawi-ence, which for 
an extent of 1,500 miles exhibit, often in spite of the forest, unequivocal signs 
of glacial abrasion, being mammillatecl (or moutonnces), as if by the action of 
ice. 
On the south side of the river, the country is low, and covered with boulder 
and other drifts, derived from the Laurentine Chain and other tracts, in accord- 
ance with the observations of Bigshy, Hitchcock, and others. The jilains and 
the Thousand Islands exhibit a general glacialization. These conditions are 
traceable down the Valley of the Hudson to New York. 
During- the ])eriod when the boulders and the associated clays and gravels were 
being deposited, theC'atskill Mountains appear to have been under water, and at about 
the same period to have been subjected also to very extensive glacial action. The 
striaj left by ice-borne rocks on the eastern flank of the CatskiUs have a north and 
south direction, and are foimd up to nearly the height of 3,000 feet above the sea, 
excepting in the east and west gorges near the to)), where the stria; run in a 
cross direction — E. and W. The sea of the di-ift-period in the Valley of the Hudson 
was then from 3,000 to 4,000 feet deep. The deep valleys on the western side of 
the mountains were observed by Prof. Ramsay to be often charged with drift, 
which had not been ploughed out by glaciers of a date subsequent to the upheaval 
of the Catskills, as is the case with some of the valleys, once occupied by drift and 
afterwards by glaciers, in Wales, the Highlands, the Vosges, and in the Alps. 
Prof. Ramsay then referred more particulai-ly to the drift-deposits forming 
terraces in the neighbourhood of Montreal, which have lately been described in 
detail by Dr. Dawson ; and pointed out his reasons for regarding the Leda-clay of 
Dawson to be of contemporaneous formation with the Nucula-clay of the 
eastern side of Lake Champlain, and with the clny-beds of Albany and elsewhere 
on the Hudson. The clay of the Hudson Valley lies on boulder-beds, and rarely 
contains boulders. Along Lake Champlain similar clays overlie old drift, at 
about 150 feet above the sea-level, and contain fossils similar to those of the 
Montreal clays, at 1 10 feet above the sea, and of other contemporaneous beds on 
the Ottawa. Prof. Ramsay assumed Dr. Dawson's conclusion as to the age of 
the Leda-beds, which were deposited, in a thickness of from 100 to 300 feet, over 
the boulder-clay, whilst the sea covered the Ontario basin, and came up against 
the great escarpment of Niagara limestone, which, now stretching across this 
region, formed the southern coast of the glacial sea. 
The author then inferred that, the Erie plateau having been elevated, llic falls 
of Niagara commenced, by the drainage of the upper lake-area, a little before the 
close of the drift-period, falling first into the sea over the edge of the escarpment 
above Queenstown and Le^vistown. If the 35,000 years suggested by Sir C. Lyell 
as the minimum for the time occupied in the erosion of the gorge of Niagara be 
approximately correct, though probably below the reality, we have an idea of the 
amount of time that has elapsed since the close of the drift ])eriod. And, if it 
be ever found possible to accurately determine the ancient rate of recession, we 
shall have data for a first approach to an actual measurement of a portion of 
geological time. This subject is intimately connected with the synchronism of 
the mastodon-bearing freshwater strata of Niagara and those of the blulis of the 
Mississippi. 
2. "On Lamination and Sleavage occasioned by the mutual fi-iction of the 
particles of rocks while in irregular motion." By Gr. Poulett Serope, Esq., M.P., 
P.R.S., F.G.S. 
The author referred to a former paper read by him before the Society in April, 
1856, in which this siibject was touched upon, and proposed to carry on the 
inquiry as to the probable effect upon the internal structure of rocks, of the 
mutual fi'iction of their component parts when forced into motion under extreme 
and irregular pressures. He commenced by examining the laws that determine the 
internal motions of substances possessing a more or less imperfect li(juidity, 
whether homogeneous, or consisting of solid particles suspended in, or mixed with, 
or lubricated by, any liquid, under unequal pressures ; and showed that unequal 
rates of motion must result in the dill'ereut parts of the substance, and that in 
