ARCHAEAN GROUP. 261 



(b) A set of hornblendic and. pyroxenic schists, diorites and diabases and 

 serpentinous rocks, whose actual relation to the other rocks are not well de- 

 fined, but which seem to be nearest to the basal gneisses. In this division 

 are included the fibrolitic and garnetiferous schists of Burnet County, as 

 well as the steatite, actinolite, labradorite, and other basic mineral belts. But 

 it must not be inferred that our study has yet been detailed enough to verify 

 their continuity across all the unexposed intervals, (Long Mountain Series.) 



(c) A comprehensive and apparently distinct collection of mica, hydromica, 

 chlorite and talcose schists and their congeners, highly siliceous for the most 

 part, with intercalated bands of quartzite and felsitic schists. (Bodeville 

 Series.) 



It is worthy of especial note that this provisional ternary grouping of the 

 Texas Burnetan strata corresponds very closely to Mr. Lawson's classification 

 of the Lake of the Woods Archaean rocks, although the writer did not know 

 this fact when the foregoing arrangement was adopted. (See page 29, C. C, 

 of the volume quoted.) It may be that the structural features can be worked 

 out in the field in 1890. A careful perusal of Mr. Lawson's report, however, 

 shows that we have almost as good evidence as he has adduced for making 

 this separation positive. But the occurrence of a basic group of rocks be- 

 tween two acidic sets is not a reliable criterion of unconformity or of epochal 

 changes in our district, at least without a better knowledge of the strati- 

 graphy of the system than we have yet acquired. Even the rough provisional 

 classification here suggested may convey more of a definite lithologic conclu- 

 sion than the facts will justify; for it is certain that the general impression 

 obtained from a review of the rocks is that the basic members are of subor- 

 dinate importance. But for the purpose of carrying into the field a convenient 

 skeleton for directing future studies, I propose to make a tentative separation 

 of the Burnetan System into series corresponding to the three sets given 

 above. The local names, Lone Grove, Long Mountain, and Bodeville, will, 

 therefore, be used for the present as titles for these suppositional epochs of 

 the Burnetan Period. 



Some of the gneisses weather into fantastic forms, and the occurrence of 



tation is from page 12 of the valuable report of A. 0. Lawson, on the Geology of the Lake 

 of the Woods Region, published as Report CO, in vol. I, 1885, of the Annual Report of the 

 Geological and Natural History Survey of Canada. Many of the features of that district are 

 strikingly like the details of the Texas Archaean, and I have been inclined, independently, 

 to adopt a view not unlike what is quoted above. But Mr. Lawson has obtained evidence 

 for his tract which is much more conclusive than mine, and I do not feel justified in giving 

 to my present views the appearance of greater weight than is due to mere personal opinion. 

 If this theory should be found tenable, a part of what is here included in the Burnetan sys- 

 tem must then be relegated to an epochal rank equivalent to Mr. Lawson's Keewatin series, 

 of uncertain affinities. 



