MARVLNE] GP:0L0GY STRATIGRAPHY OF THE EAST SLOPE. 151. 



horizontal axis, the plainer bands of rocks showing as doming over in- 

 great flat curves, with minor flexures here and there, and steepening in 

 dip on either the east or west. Long's Peak, the grandest mass of all, is 

 mostly of coarse granite, but with several lenticular masses of darker 

 schistose rock plainly showinginitsprecipitous glacier-scored sides. Ea&t 

 from Long's generally the country-rock seemed almost wholly of granite, 

 both gray and deep red, coarse, crumbling, and with large tabular feld- 

 spar crystals. But little evidence of structure was noticed, but all that 

 was observed showed eastward-dipping rocks, thus enforcing the gen- 

 eral anticlinal structure of the range. Throughout all this northern 

 portion of the map the dotted outcrop-lines are wholly approximate, 

 and intended simplj- to indicate probable structure. 



At Lilly Mountain a more schistose zone, with red granite beds con- 

 taining garnets, was found, which southward gave way to some reddish 

 granites, but seemed to again show itself somewhat plainer between 

 North and Middle Saint Train's Creeks. East of Lilly Mountain but 

 random and uncertain observations were made, but what was seen ap- 

 pears to conform to the nearest more certain observations. Close to the 

 border of the range, between the Little and Big Thompson Creeks, and 

 best exposed in the high and rather isolated hill thrown up by the eche- 

 lon folding of this region, rocks of well-defined bedding occur, gray 

 schistose gneiss, «&c., changing to hard greenish siliceous rocks, as if 

 impregnated with actinolite, while still farther out, and exposed by fiiults 

 that push aside the covering sedimentary rocks, are clear white quartz- 

 ites. Between the North and South Saint Vrain's a few strikes in the 

 mostly structureless granites would seem to indicate a pretty sharp east- 

 west anticlinal dipping east. Tracing these outer beds farther south- 

 \^'ard, a flattening of tbe formation, south of South Saint Vrain's, spreads 

 the strikes in a peculiar way, opening out or widening the outcrops of 

 the formations. Still, all the dips are eastward, except one small occur- 

 rence of white quartzite. This appeared as a ridge, only about 100 feet 

 long, rising above the soil of a flatfish contoured region, where all other 

 exposures showed the coarse, reddish, crumbling, tabular-crystalled 

 granites, with but occasional evidences of structure, which, however, as 

 just remarked, all indicate a dip in a general easterly direction. The 

 small patch of white quartzite had a well-defined trend of 15° to 25° 

 east of north, and dipped 45° northwest, as if it represented a remnant 

 of an unconformable series resting on the granites. The joints and 

 seams contained radiated actinolite, and some of the quartzite was 

 tinted green, as if containing the same disseminated in the mass. It 

 thus resembled the green siliceous rocks north of the Little Thompson 

 and elsewhere, which certainly pass into and belong to the schist series. 

 In the neighborhood of Jim Creek the observed strikes appear incon- 

 sistent with one another, and are too few to indicate what the structure 

 really is. For a little way above where Jim Creek joins Left Hand, 

 schists or banded gneisses prevail, as well as on down Left Hand to' the 

 sedimentaries, all having a general northeast strike and southeast dip. 

 They are probably the same as those a little north, near South Saint 

 Vrain's, the two apparently swinging around to join one another along 

 the eastern mountain base, the higher hills at the west being of coarse 

 granites. For some miles up Jim Creek the coarse structureless gran- 

 ites prevail, with porphyry dikes penetrating them here and there. 

 Some debris of true syenite was here seen. This irregularly-banded 

 schist-zone seems to form the high ridge between Jim and Left Hand 

 Creeks, running toward Gold Hill and dipping southeast. From Gold 

 Hill southeast a zone of similar schists and banded gneisses shows here 



