94 A. WIXCHELL — A LAST WORD WITH THE HURONIAN. 



same region. In the basin of Kamanistiquia river, which empties into 

 Thunder bay, he finds granite, syenite, gneiss, micaceous and chloritic schists. 

 These are overlain by blackish, argillaceous slates, with associated trap — 

 Logan's nos. 4 and 5. Of the lower series, he says : 



" Where they make their appearance at the lower end of the portage the character 

 of the rock is a red, or, in some instances, a whitish, massive syenite, which passes 

 gradually into a gray, gneissoid syenite, dipping at a high angle north-northwest. 

 Resting conformably on the gneiss, theie occurs a series of dark greenish-blue, or 

 greenish-black, altered slates, the one rock passing almost imperceptibly into the 

 other. * * * Towards the bottom, near the junction with the syenitic portion, 

 the slates are of a dark bluish and occasionally of a brownish color. They appear to 

 be highly altered." 



Of the upper, unconformable series of black argillaceous shales he writes: 



" The base of this formation * * * was observed on the Kamanistiquia river, 

 near the Grand falls. Its immediate junction with the rock on which it reposes was 

 concealed from view." 



Points established. — The points established by these extracts from the re- 

 ports of Logan and Murray for 1846-'47 are the following: 



1. The existence of two slate conglomerates with associated strata. 



2. The existence of an unconformity between them. 



3. The dark or black color of the upper series of slates and slate conglom- 

 erates. 



4. The greenish or bluish color of the lower series. 



5. The graduation of the lower series downward into gneissic rocks. 



6. The resemblance of the upper series to strata observed north of Lake 

 Huron. 



Logan'' s Identification of Huron and Superior Rocks. — Some account of Mr. 

 Murray's report on the region north and northeast of Lake Huron has 

 already been given. Director Logan himself subsequently published^ com- 

 ments, comparisons and inferences based on Murray's report, from which the 

 following extracts are taken : 



'* The series of rocks occupying this country form the connecting link between 

 Lakes Huron and Superior to the vicinity of Shebawenahning, a distance of 120 miles, 

 with a breadth in some places of 10 and in others exceeding 20 miles, [and] it appears 

 to me must be taken as belonging to one formation. On the west it seems to repose 

 on the granite which was represented in my report on Lake Superior as running to 

 the east of Gros Cap, north of Sault Ste. Marie. On the east the same supporting 

 granite was observed by Mr. Murray north of La Cloche, between three and four 

 miles in a straight line up the Riviere au Sable, * •* * and again about an equal 

 distance up another and parallel tributary, * * * in both cases about ten miles 

 from the coast. * * "^ In respect to the geological age of the formation, the evi- 

 dence afforded by the facts collected last year by Mr. Murray * ■5«- -s^- is clear, sat- 



* Report on the North Shore of Lake Huron, December 29, 1848. 



