316 THE CANADIAN NATURALIST. [Aug. 



may in part be dolomitic like the similar calcareous beds of the 

 Laurentian. 



11 Coldbrook Group.— Characters.— It has been stated that 

 the Coldbrook group consists of two inembers, an upper, soft, red, 

 and of aqueous origin, and a lower, in which the rock is chiefly a 

 hard greenish-grey compact slate. There is but little variation in 

 the characters of these members throughout their entire extent. 



" In the neighbourhood of Saint John the development of the 

 group is of too limited character to serve for illustration. Widen- 

 ing however, to the eastward, it is well exposed along the valley of 

 the Coldbrook, and the following succession has been observed by 

 Mr. Matthew :— 



1. Hard greenish-gray slate, stratification very obscure. 



2. Conglomerate, with bright red slaty paste. 



3. Grey conglomerate. 



4. Coarse reddish grit, and conglomerate with purple sandstone. 

 Apparent thickness of the whole, 5000 feet. 



" In tracing the group to the eastward, along the northern side of 

 the Loch Lomond Lakes, two sections have been made across the 

 lower member of the series, the first extending from "the Thorough- 

 fare" between the first and second lakes, to the Golden Grove 

 settlement, the second from the latter to the third lake, thus re- 

 crossing the same ridge. 



" Along the line of the first section, the rocks of the group differ 

 from their development westward, chiefly in the occurrence of a 

 middle band of sandstone and shale, resting upon a thick succession 

 of porphryitic and amygdaloidal traps, associated with bands of 

 ferruginous and white feldspathic quartzites. Near the lower part 

 of Golden Grove, the base of the Coldbrook group is represented by 

 the occurrence of heavy beds of dark-grey sandstones and coarse 

 quartzose conglomerates, the latter much faulted and injected. 



" The great thickening of the Coldbrook beds in this vicinity is 

 probably, as suggested by Mr. Matthew, the cause of the decided 

 easterly trend noticeable in the upper member of the present group, 

 as well as in the overlying deposits. 



" Along the second section referred to, no facts additional to those 

 now given were observed, with the exception that a portion of the 

 series near Brawly Lake has been exposed by an extensive slide, 

 and now projects in wild and lofty overhanging cliffs above the 

 ruin at its base. 



u It has been stated that rocks apparently forming a portion of 

 the upper member of the group now under consideration, occur 



