766 
theory, though he rejects its application to the case investigated in 
this communication as altogether unnecessary to account for the 
observed phznomena, he conceives that floating ice may probably 
have been the most efficient agent in transporting the larger blocks 
of colder regions from their original localities. 
June 15.—A paper was first read “ On the packing of Ice in the 
river St. Lawrence ; on a Landslip in the modern deposits of its 
valley ; and on the existence of Marine Shells in those deposits as 
well as upon the mountain of Montreal.” By W. E. Logan, Esq., 
F, a S. 4 
. The paper commences with a general description of the river 
oH Lawrence, from the junction of the Ottawa in Lake St. Louis, 
above Montreal, to Lake St. Peter, fifty miles below it, with a more 
particular account of the rapids of Lachine and the Sault Normand, 
produced by ledges or floors of trap rock. The author then proceeds 
to give an account of the packing of the ice near Montreal. 
The frosts commence about the end of November, and a margin of 
ice of some strength soon forms along the shores ; and wherever the 
water is still, it is immediately cased over. The first barrier completed 
across the river below Montreal is usually formed about Christmas, at 
the entrance of Lake St. Peter’s, where the St. Lawrence is divided 
into a multitude of channels by low alluvial islands. This barrier is 
rapidly increased by extensive fields of drift-ice, enormous quantities 
of which are heaped upon, or forced under, the stationary mass. The 
space left for the water to flow being thus greatly diminished, a per- 
ceptible rise in the river takes place, and by the time that the ice 
becomes stationary at the foot of St. Mary’s current, opposite Mont- 
real, the waters in the harbour have usually risen several feet, and as 
the packing rapidly proceeds, they soon attain the height of twenty, 
and sometimes twenty-six feet, above the summer level. It is at 
this period that the grandest glacial phenomena are presented. 
In consequence of the packing and piling of the ice, as well as the 
accumulation of the moistened snow of the season, and the freezing 
of the whole into a solid body, sometimes more than twenty feet 
thick, the water suddenly rises, and lifting a wide expanse of the en- 
tire covering of the St. Lawrence, urges it forward with terrific vio- 
lence, piling up the rended masses on the banks of the narrower 
parts of the river to the height of forty or fifty feet. In front of 
Montreal is a newly built revétement, the top of which is twenty- 
three feet above the summer level of the river; but the ice broken by 
it, accumulates on the surmounting terrace, and before the wall was 
erected the adjacent buildings were endangered, the ice sometimes 
breaking in at the windows of the second fluor, even 200 feet from 
the margin of the river. In one instance, a warehouse of considerable 
strength and magnitude, having been erected without due protection, 
the great moving sheet of river-ice pushed it over as if it had been a 
house of cards ; and in another case, where a similarly situated and 
equally extensive warehouse, four or five stories high, had been provided 
witha range of oaken piles placed at an angle of less than 45°, the drift 
