REPORT OF TEE CEIEF ASTRONOMER 395 



SESSIONAL PAPER No. 25a 



No single section gives the whole thickness of the formation and all of the 

 different sections together do not afford a strict idea of the total thickness nor 

 of the exact strength of each member. Moreover, from the nature of the forma- 

 tion it is highly probable that none of the members originally held a given 

 thickness for many miles across country. A complete columnar section cannot, 

 therefore, as yet be constructed. All that is now possible is to state the general 

 succession of the beds and the minimum thickness of each member in its 

 thickest section, and thus to indicate a minimum thickness for the whole 

 formation where most completely developed. 



The columnar section worked out on this basis may be described as follows : 



Columnar section of Kettle River formation. 



Top, conformable contact with overlying Midway lavas. 

 1,000-ffeet — Fossiliferous, gray, feldspathic sandstones with thin interbeds of shale. 

 900-f- " Coarse conglomerate. 

 200-f- " Coarse arkose-breccia (a local deposit). 



2,100+ " 



Base, unconformable contact with underlying Anarchist series and with pre- 

 Tertiary plutonic intrusives. 



The basal arkose-breecia crops out only in one place, in the form of an 

 elongated area cresting the north wall of Rock creek canyon between the forks 

 and Johnston creek. It is composed of angular to subangular blocks of the 

 diorite and granodiorite on which the breccia lies, so that it is likely that few 

 or none of the blocks have travelled far from their parent Tertiary ledges. 

 The blocks are of variable size, many of them being four feet or more in 

 diameter. Very few are rounded; it is not certain that any at all are water- 

 worn. The cement is simply the disintegrated, highly feldspathic material of 

 the granitic rocks. From its evidently local nature one would not expect the 

 breccia to form the base of the formation generally. In fact, that member is 

 wanting at the lower contacts where the formation rests on the Anarchist 

 quartzites and phyllites; such contacts were discovered at several points to the 

 south of the Kettle river and of Rock creek. 



The conglomerate is well exposed in Rock creek canyon from one to two 

 miles upstream from its mouth, and again, on the summit immediately south 

 of the Riverside hotel. In the former locality it forms part of the roof of the 

 Rock creek chonolith of rhomb-porphyry. At the latter locality the conglom- 

 erate lies, with evident unconformity, on the Anarchist quartzites and green- 

 stones. In neither case nor at any other locality was the top of the conglom- 

 erate recognized; its uppermost beds have been eroded away or faulted out of 

 sight. 



The rock is a well consolidated, gray to brownish mass of rounded pebbles 

 and boulders of all diameters up to three feet. These are almost always well 

 water-worn. In composition they reflect the formations on which the conglom- 

 erate rests; gray quartzite, white and gray limestone, vein quartz, slate, phyllite, 

 greenstone, amphibolite, altered porphyrites, and granodiorite are all more or 



