i 1 



CANADA. 



333 



Logan in the Eoport of Progress for 184G-47 described the series on 

 the north shore of Lake Superior in ascending order, as follows {l. c, 



pp. 8-17) : 



" 1. Granite and syenite. 



*'2. Gneiss. 



" 3. Chloritic and partially talcose and conglomerate slates. 



"4. BluiHb slates or shales, interstiatified with trap. 



*' 5. Sandstones, limestones, indurated marls, and conglomerates, interstrati- 



fied with trap. 



" The rock at tlie base of the series is a granite, frequently passing into a 

 syenite by the addition of horublenih', but the hornblende does not appear to 



be often present wholly without the mica The granite appears to pass 



gradually into a gneiss, which seems to participate as often of a syenitic as a 



granitic quality The gneiss is succeeded by slates of a general exteiior 



dark green colour, often dark-gray in fresh fractures, which at the base apj)ear 

 occasionally to be intcrstratified with beds of a feldspathic quality, of the red- 

 dish color belonging to the subjacent granite and gneiss Some of the 



beds have the quality of a greenstone, others that of a mica slate, and a few 

 present the character of quartz rock. Rising in the series, these become inter- 

 stratified with beds of a slaty character, holding a sulFicient number of pebbles 

 of various kinds to constitute conglomerates. The pebbles seem to be of 



various qualities, but apparently all derived from hypogene rocks The 



formations which succeed, rest unconformably upon those already mentioned. 

 The base of the lower one [No. 4], wdiere seen in Thunder Bay in contact with 

 the subjacent green slates, presents conglomerate beds probably of no great 

 thickness, composed of quartz pebldes chieHy, with a few of red jas})er, and 

 some of slate in a green arenaceous matrix, consisting of the same materials in 

 a finer condition." 



f'l 



Eoposing on the bluish slates (No. 4) are "sandstones, limestones, 

 indurated marls and conglomerates intcrstratified with trap," and 

 crowned by an enormous amount of volcanic overflow. No evidence 

 ia adduced to show that these two '* volcanic formations " are uncon- 

 formable with each other, but sufhciont proof is cited to show that they 

 are nnconformable with the granite, gneiss, and chlorite slate. The 

 volcanic formations are, however, regarded as being older than the 

 Potsdam sandstone. (Z. c, p. 34.) 



Logan further remarks : 



i;^ ;h 



ill 



J': 



. ■ 



" The chloritic shites at the summit of the older rocks on which the volcanic 

 formations rest unconformably, bear a strong resemblance to those met with in 

 the upper part of Lake Temiscamang on the Ottawa, and it appears probable 

 they will be found identicah" (I. c, p. 34.) 



