ARCHEAN SURFACE UNCHANGED SINCE THE NIl'IGON. 167 



beds of the Nipigon resting in situ in the hollows between the Laurentian 

 hummocks, both at the bottoms of the hollows and on the steep slopes. 

 These patches are usually not more than a few chains in diameter ; and their 

 relation to the Laurentian affords incontestable proof that the surface of 

 the latter has undergone uo material change since they were deposited upon 

 it. At Rossport the Animikie rocks come in again between the Archean 

 and the Nipigon, and here also may be seen, near the railway station, in a 

 hollow between the Laurentian hillocks, an outlying patch of the basal beds 

 of these rocks. 



Along the shore of the lake between Rossport and Black river, north of 

 the Slate islands, there are occasional patches of the Nipigon amygdaloidal 

 traps which have escaped removal by erosive agencies, and these all repose 

 upon a hummocky Archean surface. In none of these instances is there 

 any evidence of a perceptible reduction of the mean level of the glaciated 

 surface of the Archean below that upon which the Nipigon or Animikie 

 rocks rest. A noteworthy fact also is, that with one exception none of the 

 Archean rocks, where they pass immediately beneath the Animikie or Nipi- 

 gon, show the slightest evidence of decay. On the contrary, they are 

 remarkably fresh and free from even the incipient decomposition of weather- 

 ing. The exception is the case of the schists in the rock cut east of Pearl 

 river mentioned above. All the Laurentian gneisses and granites are per- 

 fectly fresh in their macroscopic aspects. Another interesting point, which 

 will be alluded to again, is the transgression northward of the newer Nipigon 

 rocks beyond the edge of the older Animikie. 



The Phenomena in Eastern Canada. 



On instituting a comparative inquiry into the conditions which obtain 

 along the escarped line of the abutment of the undisturbed Paleozoic upon 

 the Archean in eastern Canada, it is found that the evidence here confirms 

 the conclusions arrived at on Lake Superior as to the general character of 

 the pre-Paleozoic Archean surface. 



Contacts between the Paleozoic and the Archean. — Laflamme in his " report of 

 geological observations in the Saguenay region"* seems to have arrived at 

 much the same conclusion as the writer. After describing a new area of 

 the Trenton rocks in the vicinity of the Saguenay " which rest directly on the 

 gneiss," and stating that "their thickness is so slight, at least on the border 

 of the formation, that the undulations of the gneiss are brought to light 

 through their edge," he gives an account of various outliers and says by way 

 of summary : " I have pointed out in the course of these remarks the fact 

 that limestones (Trenton) are often found iu nests or outliers amongst the 



*Geol. Survey of Canada, Report Progress for 1882-3-4, Part D. 



