424- PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



gains any position where the current is stronger than usual. The 

 augmented force with which the masses there move, pushes and 

 packs so much below, that the space left for the river to flow in is 

 greatly diminished, and the consequence is a perceptible rise of the 

 waters above, which indeed from the very first taking of the bridge 

 gradually and slowly increase for a considerable way up. 



There is no place on the St. Lawrence where all the phaenomena of 

 the taking, packing and shoving of the ice are so grandly displayed 

 as in the neighbourhood of Montreal. The violence of the currents 

 is here so great, and the river in some places expands to such a width, 

 that whether we consider the prodigious extent of the masses moved, 

 or the force with which they are propelled, nothing can afford a 

 more majestic spectacle, or impress the mind more thoroughly with 

 a sense of irresistible power. Standing for hours together upon the 

 bank overlooking St, Mary's Current, I have seen league after league 

 of ice crushed and broken against the barrier lower down, and there 

 submerged and crammed beneath ; and when we reflect that an ope- 

 ration similar to this occurs in several parts from Lake St. Peter 

 upwards, it will not surprise us that the river should gradually swell. 

 By the time the ice has become stationary at the foot of St. Mary's 

 Current, the waters of the St. Lawrence have usually risen several 

 feet in the harbour of Montreal, and as the space through which 

 this current flows affords a deep and narrow passage for nearly the 

 whole body of the river, it may well be imagined that when the 

 packing here begins the inundation rapidly increases. The confined 

 nature of this part of the channel affords a more ready resistance to 

 the progress of the ice, while the violence of the current brings such 

 an abundant supply, and packs it with so much force, that the river, 

 dammed up by the barrier, which in many places reaches to the 

 bottom, attains in the harbour a height usually twenty, and some- 

 times twenty-six feet above its summer level ; and it is not uncom- 

 mon between this point and the foot of the current within the 

 distance of a mile, to see a difference in elevation of several feet, 

 which undergoes many rapid changes, the waters ebbing or flowing 

 according to the amount of impediment they meet with in their 

 progress from submerged ice. 



It is at this period that the grandest movements of the ice occur. 

 From the effect of packing and piling and the accumulation of the 

 snows of the season, the saturation of these with water, and the 

 freezing of the whole into a solid body, it attains the thickness of 

 ten to twenty feet, and even more ; and after it has become fixed as 

 far as the eye can reach, a sudden rise in the water, occasioned no 

 doubt in the manner mentioned, lifting up a wide expanse of the 

 whole covering of the river so high as to free and start it from the 

 many points of rest and resistance offered by the bottom, where it 

 had been packed deep enough to touch it, the vast mass is set in 

 motion by the whole hydraulic power of this gigantic stream. Pro- 

 ceeding onward with a truly terrific majesty, it piles up over every 

 obstacle it encounters; and when forced into a narrow part of the 

 channel, the lateral pressure it there exerts drives the bordage up the 



