1853] WINTER PHENOMENA 



Winter Phenomena in the St, Lawrence. • 



The island of Montreal stands at the confluence of the rivers Ottawa 

 and St. Lawrence, and is the largest of several islands splitting up 

 these mighty streams, which cannot, be said tu be thoroughly mingled 

 until they have descended some miles below the whole cluster. The 

 rivers first conse iu contact in a considerable sheet of waier called 

 Lake St. Louis, which separates the upper part of the Island of Mon- 

 treal from the southern main. But though the streams here touch, 

 they do not mingle. The waters of the St. Lawrence, which are 

 beautifully clear and transparent, keep along the southern shore, while 

 those of the Ottawa, of a darker aspect, thou_h by no means turbid, 

 wash the banks of the island ; and the contrast of colour they present 

 strongly marks their line of coulact for many miles. 



Lake St. Louis is at the widest part about sis miles broad with a 

 length of twelve miles. It gradually narrows towards the lower end, 

 and the river as it issues from ir, becoming compressed into the space 

 of half a mile, rushes with great violence down the rapids of Lachine, 

 and although the stream is known to be upwards of eight feet deep, it 

 is thrown into huge surges of nearly as many feet high as it par-Sirs 

 over its rocky bottom, which at this spot is composed of layers of 

 trap extending into floors that lie in successive steps. 



At the termination of this cascade tl e river expands to a breadth of 

 four miles, and flows gentlj on, until it again becomes cramped up by 

 islands and shallows opposite the city of Montreal. From Windmill 

 Point and Point St. Charles above the town, several ledges of rock, 

 composed of trap lying in floors, Which iu seasons of low water are 

 not much below the surface, shoot out into the stream about 1000 

 yards : and similar layers pointing to these come oat from Longueuil 

 on the opposite shore. In the narrow channel between them, the 

 water, rushing with much force, .produces the Sault Normand, and 

 eooped up, a little lower down by the island of St. Helen and several 

 projectirg"patches of trap, it forms St. Mary's current. 



The interval between St. Helen and the south shore is greater than 

 t hat between it and Montreal ; but the former is so floored and crossed 

 by hard trap rocks that the St. Lawrence has as yet produced but 

 little effect in wearing them down, while in the latter it has cut out a 

 channel between thirty and forty feet deep, through which the chief 

 part of its waters rush with a velocity equal to six miles per hour. It 

 is computed that by this channel alone upwards of a million of tons 

 flow past the town every minute. 



Between this point and Lake St. Peter, about fifty miles down, the 

 river has an average breadth of two miles, and proceeding in its courso 

 with a moderate current, accelerated or retarded a little, according to 

 the presence or absence of shoals — it enters the lake by a multitude of 

 channels cut through its delta, and forming a group of low flat alluvial 

 islands. 



The frosts commence about the end of November, and a margin of 

 ice of pome strength soon forms along the shores of die river and 

 around every island and projecting rock in it : and wherever there is 

 still water it is immediately cased over. The wind, actiug on this 

 glacial fringe, breaks off portions in various parte, and these proceed- 

 ing down the stream constitute a moving border on the outside of the 

 stationary one which, as the intensity of the cold increases, is con- 

 tinually augmented by the adherence of the ice sheets which have 

 been coasting along it : and as the stationary border thus lobs the 

 moving one this still further outflanks the other, until in some part the 

 margins from the opposite shores nearly meeting, the floating ice be- 

 comes jammed up between them, and a night of severe frost forms a 

 bridge across the river. The first ice bridge below Montreal is usually 

 formed at the entrance of the river into Lake St. Peter, where the 

 many channels into which the stream is split up greatly assist the 

 process. 



As soon as the winter barrier is thrown across, (generally towards 

 Cbiistmas,) it of course rapidly increases by stopping the progress of 

 the downward floating ice, which has by this time assumed a charac- 

 ter of considerable grandeur, nearly the whole surface of the stream 

 being covered with it, and the quantity is so great, that to account 

 for the supply many, unsatisfied with the supposition of a marginal 

 origin, have recourse to the hypothesis that a very large portion is 

 formed on and derived from the bottom of the river where rapid cur- 

 rents exist. 



But whatever its origin, it now moves in solid and extensive fields, 

 and whereier it meets with an obstacle in its course the momentum 

 of the mass breaks up the striking part into huge fragments that pile 

 over one another : or if the obstacle be stationary ice, the fragments 



* Contributed to the Geological Society of London, June loth, 1S42, by 

 "W. E. Logajj, Esq , Provincial Geologist. 



IN THE ST. LAWRENCE. 



75 



are driven under i', and there closely packed. Eeneaih the constant- 

 ly widening ice barrier mentioned, an enormous quantity is thus 

 driven, particularly lien the barrier g- ins any position where the 

 curiect is stronger than usual. The augmented force with which the 

 masses then move, pushes and packs so much below that the space 

 left for the liver to flow iu 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 increases for a con- 

 sideiable way up. 



There is no place on the St. Lawrence where all the pjhenomena 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 ate pi op lied, 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, 1 have seen league after league of ice 

 crushed and broken against the barrier lower down, and there sub- 

 merged and crammed beneath. And when we reflect that an opera- 

 tion similar to this occurs in several parts from Lake St. Peter up- 

 wards, 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 tire channel affurds 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 iu 

 the harbour a height usually twenty, and sometimes twenty-five feet 

 above its summer level ; audit is not uncommon between this point 

 and the foot of the current, within the distance of a mile, to see a dif- 

 ference in elevation of several feet which undergoes marry rapid, 

 changes, tl e waters ebbing or flowing according to the amount of im- 

 pediment 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 i«toa solid body, it attains the thickness of ten to twenty 

 feet and even more : and after it has become fixed as far as the eya 

 can reach, a sudden rise in the water (occasioned, no doubt, in the 

 manner mentioned) liftiug 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 iu motion by the whole hy- 

 draulic power of this gigantic stream. Proceeding 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 pres- 

 sure it there exerts drives the bordage up the banks where it sometimes 

 accumulates to the height of forty or fifty feet. In front of the town 

 of Montreal there has lately been built a magnificent revetment wall 

 of cut limestone to the height of twenty-three feet above the summer 

 level of the river. This wall is now a great protection against the effects 

 of the ice: Broken by it, the ice piles on the street or terrace sur- 

 mounting it, and there stops ; but before the wall was built, tho 

 sloping bank g'.ided the moving mass up to those tf gardens and 

 houses in a very dangerous manner, and many accidents used to oc- 

 cur. It has been known to pile up against the side of a house distant 

 more than 200 feet from the margin of the river, and there break in at 

 the windows of the second floor. I have seen it mount a terrace gar- 

 den twenty feet above the bank, and crossing the garden enter one of 

 the principal streets of the town. A few years before the erection of 

 the reyeiment wall, a friend of mine, tempted by the commercial ad- 

 vantages of the position, ventured to build a large cut stone warehouse. 

 The ground floor was not more than eight feetabove the summar level 

 of the river. At the taking of the ice, the usual rise of the water of 

 c urse inundated the lower story and the whole building becoming 

 surrounded by a frozen sheet, a general expectation was entertained 

 that it would be prostrated by the first movement. But the proprietor 

 had taken a very simple and effectual precaution to prevent this. Just 

 before the rise of the waters he securely laid against the sides of the 

 building at an angle of less than 45 °, a number of stout oak logs a 

 few feet asunder. When the movement came the sheet of ice was 

 broken, and pushed up the wooden inclined plane thus formed, at the 

 top of which, meeting the wall of the building, it was reflected into a 

 vertical position, and falling back in this manner, such an enormous 

 rampart of ice was in a few minutes placed in front of the warehouse 

 as completely shielded it from all pos.-ible danger. In scm? years lie 



