31 



Westward of Boundary brook, a large stream called Gregwa brook, Section of 

 runs across the Indian reservation. In its lower course it in cut down (j^Lva" 1 

 nearly to the level of Indian brook, of which it is a tributary, and so ^rook. 

 does not give continuous exposures. In going up the stream the first 

 ledges met with are the felsite-congloaierates of the Acadian division 

 of the St. John group. The intervening flags and slates, being softer, 

 are not exposed. A fine-grainod slate appears further up stream in 

 which no fossils were found, and beyond this, in the banks and 



channel, gray shales occur. These shales contain Obolus Bretonensis Upper 



1 J and Middle 



and an Acrothele and therefore are assigned to Assise a of the Etcheminian. 



Upper Etcheminian. The valley here is narrowed by abrupt hills, 

 which consist of purplish-gray feldspathic sandstones, rich in iron, 

 as they contain fahlbands of hematite. These sandstones belong to 

 Division 2 of the Etcheminian terrane. 



Above this, on the east branch of this brook, are some exposures of Lower divi- 

 gray rusty-weathering shales, holding the place of Assises c, d and e of same and the 

 the lower division of the Etcheminian terrane. Further up the brook t e ran e c 

 are purplish-red schist and sandstone that hold the place of Assises a 

 and b of this division. They dip N. 30 W. mag. < 70. Here the 

 section passes to the gray amygdaloids and feldspathic rocks of the 

 Coldbrook terrane, over which this branch falls in cascades to the 

 valley below. Above the falls these effusives continue for a short 

 space and show purplish-red felsite rock, porphyritic and amygdaloi- 

 dal. There is no great body of these effusives. On the main or west 

 branch of Gregwa brook a similar succession is found. Here the 

 lowest Etcheminian beds seen correspond to Assises a and b of Divi- 

 sion 1, and consist of dark-red, crumbling calciferous conglomerate; 

 this passes into a dark- red sandstone, and is succeeded by red, and 

 then gray quartzites in massive beds. 



An examination was made of the Etcheminian and St. John terranes Section of 

 at Gillis brook, a branch of Indian brook, to near its source, for com- Giiiis' brook 

 parison with the section of Dugald brook. This section is about two j e f l j p ^' n 

 and a half miles north-east of Dugald brook. There are two branches brook valley. 

 of this brook, of which the western comes down from a granite hill to 

 the north of Gillis house, and the eastern comes from lower land to 

 the eastward, but traverses the same terranes as the western branch. 



Where the western branch comes off the granite hill, a thin body of 

 amygdaloidal ash- rock is all there is to represent the Coldbrook terrane. 

 Resting on this is a narrow ridge of pink quartzites, upon which lie 

 some beds of purplish-red sandstones. South of these there is a space 

 where the measures are concealed, and following this the felsite breccia- 



