the Geology of the North Coast of the St. Lawrence. 95 



That several similar elevations of the land or depressions of the sea would be necessary to 

 account for all the appearances on the Mingan islands, may be inferred from the following. 



We ascended several times cliffs at the water's edge, and on their summits, thirty feet above 

 high tide level, we found beaches of limestone pebbles, more or less rounded and water-worn, 

 which were continually falling down as the cliffs gave way beneath them, by the undermining of 

 the waves or of the elements. In rear of the first beach I counted five or six others, each higher 

 than the preceding, and all more or less covered with vegetation, and the higher ones with trees. 

 The highest was sixty or seventy feet above the sea. Appearances exactly similar have been 

 observed on Lake Huron, and described in a paper published in the Transactions of the Literary 

 and Historical Society of Quebec*. 



Most of the flower-pots and other columns were from fifteen to thirty feet, but some exceeded 

 forty feet in height above the plateau of rock on which they stood. They were frequently ar- 

 ranged in lines upon a terrace of limestone, precisely as they are forming at present, at the water's 

 edge, out of cliffs which are washed by the waves. 



In those columns which have been successively worn or scooped out by the waves at different 

 levels, it is not unworthy of remark, that the part so worn generally corresponds, in perpendicular 

 height, to the rise of the tides at present ; thus leading to the inference, that although the level of 

 the land or sea must have changed to produce the appearances described, yet that that change has 

 not been sufficient to materially modify the circumstances, upon which the heiglit of the tidal wave, 

 in an estuary, depends. 



A faithful record of the powerful effect of natural agents, in the present day, will best enable 

 us to judge of the past. It is, on this account, that I mention an instance of the partial destruction 

 of these rocks, during an absence of ten months from the Mingan islands. In the autumn of 

 1831, we noticed several remarkable flower-pot columns on the east side of Mingan island, some 

 near the water, others considerably above its level. We were familiar with their shape and 

 appearance, having looked at them frequently through our telescopes, and used them as 

 stations in the trigonometrical survey. Lieutenant Collins had also examined them closely. 

 On our return, in June, 1832, we found the heads of several of these flower-pot columns broken 

 off by an agent, traces of which still remained. An immense bank of ice and snow was on the 

 island, in rear of the broken columns, and was not totally dissolved on the 17th of July, when 

 we last saw it. This had doubtlessly been forced up during heavy easterly gales, and the 

 pressure of the ice had broken off the heads of the flower-pot columns. 



This change of level appears to me of so much interest, that I must add a few more remarks 

 respecting it, before I proceed with my description of the Mingan islands. 



In almost every part of the estuary of the St. Lawrence, we observed other appearances which 

 we could also account for only by supposing either that the level of the sea, in the estuary and 

 gulf, has fallen, or that the land has been elevated. In many bays and entrances of valleys near 

 tlie sea, are sandy terraces at different levels, corresponding on opposite sides, and so shaped that 

 it was impossible to resist the idea, they had once formed the margin of the ocean. I have 

 mentioned (2. p. 89), that the rivers have cut sections through the soft strata of clay, sand, and 

 gravel, and that the detritus which they bring down, is princiiJally derived from these formations. 

 I have also alluded to the resemblance between these more ancient strata and those of undoubted 

 alluvial origin, which have been formed and are still forming at the mouths of those rivers. 



Vol. i. p. 6.— 1829. 



