SEDIMENTARY ROCKS 189 



varying displacement intersecting the beds in different directions. Al- 

 though these beds are so greatly disturbed, metamorphism is not pro- 

 nounced in the different members of the group, and the rocks themselves, 

 although considerably indurated, have nowhere, for instance, a schistose 

 or gneissoid structure, and seldom, if anywhere, possess a slaty cleavage. 

 They are thus very different in this respect from the members of the 

 Yukon group. 



Occasional dikes and small intrusive masses of diabase pierce these 

 rocks in places, and since the dikes rarely extend up into the overlying 

 Paleozoic rocks, the diabase is probably older than the latter. 



These rocks, where exposed to the south along Tindir Creek and be- 

 tween Ettrain and Harrington Creek, resemble very closely those on the 

 Porcupine; to the south, however, greenstones are developed to a much 

 greater extent, and the quartzites instead of being dominantly white to 

 grayish include more greenish, reddish, and dark colored members. As 

 to the north, the Tindir rocks here are characteristically brightly and vari- 

 colored, and the hills on which they outcrop can generally be distinguished 

 for several miles, these bright colored rocks constituting one of the most 

 striking features of the landscape. 



To the north of Harrington Creek the members of the Tindir group 

 distinctly underlie unconformably the Cambrian limestone-dolomite beds 

 of Jones ridge ; and along Porcupine Eiver, also, the Tindir rocks are evi- 

 dently overlain by the limestone-dolomite beds, in which Middle Cambrian 

 fossils were found. Below the horizon from which these Middle Cambrian 

 remains were obtained, there occur in places several hundred feet of litho- 

 logically similar, but unfossiliferous, limestones and dolomites, which in 

 all probability represent the Lower Cambrian, and underlying these beds 

 unconformably occur the Tindir rocks. The members of the Tindir group 

 are thus either of Lower Cambrian or pre-Cambrian age. Considering, 

 however, the great thickness of these rocks, the fact that they differ so 

 greatly lithologically from the overlying beds of Middle and Upper Cam- 

 brian age, and that the Lower Cambrian is probably represented by the 

 lowest beds of the overlying limestone-dolomite formation, from which 

 lowest beds no fossils have as yet been obtained, it would seem to the 

 writer very probable either that the Tindir rocks are entirely of pre- 

 Cambrian age or that this group includes both Lower Cambrian and pre- 

 Cambrian members. 



The Tindir group appears to correspond to the Belt Terrane^' of Brit- 



2T R. A. Daly : Geol. Surv., Canada, Memoir No. 38, 1912, pp. 179-191. 

 S. J. Schofield : Geological reconnaissance in East Kootenay, British Columbia. Sum. 

 Rept. 1912, Geol. Surv., Canada. See section on correlation. 



C. R. Van Hise and C. K. Leith : Pre-Cambrian geology of North America. U. S. 

 Geological Survey, Bull. 360, 1909, pp. 98, 852, 856-857, 858, 860-864, 881. 



