EAMSAT DBIFT-PERIOD OF CANADA. 205 



run S. from 5° to 10° E. on a smoothed surface of Calciferous Sand- 

 rock ; and at Niagara, on the limestone, S. 30° W., with minor stri- 

 ations crossing each other at various angles. Near Avon, at Conesus 

 Outlet, in the Genesee Yalley, on the Comiferous Limestone, the chief 

 striae run S. 10° W., crossed by many minor scratches, having a general 

 southern course. These crossings might be expected, if the striae 

 were produced by floating ice subject to minor variations of the 

 currents, and to the influence of winds. The rock is overlaid by 

 clay containing scratched subangular stones. At Genesee, under 

 6 feet of drift-clay full of scratched stones, the striae run S. 5° W. ; 

 and near Portage, on the top of the gorge, 350 feet deep, the striae 

 run a little west of south. 



The rocks of the St. Lawrence, where it flows from Lake Ontario, 

 deserve more special notice. Above its junction with the Ottawa, 

 the banks of the St. Lawrence are low and shelving, and the rocks are 

 in general obscured by drift ; but between Brockville and Lake On- 

 tario, where the river widens and winds amid the intricacies of the 

 Thousand Isles, while the larger islands are partially covered with drift, 

 and well wooded, the lower islets are often only scantily clothed with 

 grass and a few stunted trees and shrubs. Some of them are formed 

 of Laurentian gneiss, and others of Potsdam sandstone. The Pots- 

 dam sandstone above the river-bank at Brockville has been ground 

 smooth, and in waving Hnes passes under the river. The islands 

 formed of Laurentian gneiss or Potsdam sandstone present the 

 same largely mammillated surfaces, rising from the midst of the 

 river, which between Brockville and the lake gradually increases to 

 9 or 10 miles in width. All of them are moutonnees, somewhat like 

 the islands of Loch Lomond ; and the surfaces of the little islets often 

 slip under the water quite smooth and unbroken. 



This is one of those cases in which it might be contended that the 

 glaciation of these rocks may be due to the floating ice of the river 

 when it breaks up in spring. But though it may produce slight 

 effects, there are several conclusive reasons why the greater features 

 should not be referred to this cause. The old glaciation has passed 

 up the country quite beyond the reach of the present river, while the 

 tops of most of the islands rise far above the extreme height of the 

 water ; and again, some of the islands with well-rounded glaciated 

 surfaces present vertical cliflfe to the river, sometimes 20 feet in 

 height, where the rocks have spKt away at the joints ; and on these 

 cliffe I observed no sign of that glaciation which we should expect 

 to find if the river-ice exercised any important influence. Further, 

 it was observed by Sir Wm. Logan, that if the smoothing were pro- 

 duced by river-ice, many of the trees of the islets would be shaved 

 off by the yearly ice, — whereas, when untouched by man, they grow 

 to the water's edge. At the only place I landed (a wooding- 

 station), the rock had been too long exposed to the weather to 

 retain its striations; but as we passed the islands, I could see 

 indications of striae ; and it is to be wished that some one would 

 settle the point by determining their exact bearings, the chief direc- 



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