BT.JOHN.l BLACKFOOT RANGE — SECTION. 339 



is reached in about four miles from the mouth of the creelc, and it is bro- 

 ken throiigii at tliis point by a narrow jj;orj;e, wliich is vsallcd in by jn-e- 

 cipitous exi)osures of Carboniferous limestone, dippini>- at aufilos of UP 

 to iHP, soutlnvestward. A short distance to the nortliward of the Wol- 

 verine Canon the limestone ridge ceases, the volcanics rising iij* all 

 around the northern end of the range, where the edges of the ui>raised ba- 

 salt are shown in abrupt benches facing the range and sh)ping oft' toward 

 the plain in a series of broad, gentle terraces. The cavernous rocky 

 ridge harbors multitudes of rattlesnakes whose magnanimous alarm was 

 a continual warning to exercise wariness while prosecuting geological 

 studies in their neighborhood. 



The Wolverine opens out into a beautiful little mountain-basin wedged 

 in between the two branches of the range, on the south bounded by 

 rugged, wooded hills, which send down sharp spiu's, and on the north 

 undulating grass-covered slopes interspersed with groves of aspen de- 

 scend from a high ridge on the north in which obscure indications of 

 limestone ledges and hea^-y masses of vesicular trachytic lava are seen. 

 This basin is about 2 miles across. To the northeast an isolated cluster 

 of hills culminates in Blackfort Peak, the whole southwest ilank of which 

 is plated with several hundred feet thickness of limestone and siliceous 

 beds, probably belonging to the uj)per measures of the Carboniferous. 

 The outcropping edges of the several ledges form the crests of so many 

 spurs descending from the summit and in the southwest flank of the 

 mountain, cut by narrow ravines with intervening broad ridges which 

 fall steeply mto the valley over the inclination plane of the beds. On 

 the northeast side the mountain descends even more abruptly, the face 

 being broken by outcropping edges of limestone, into a deep valley 

 which separates it from the low outlying hills in that direction. Hence 

 it is seen that the Blackfoot Peak forms the crest of a monoclinal whose 

 axis Ues in a general northwesterly and southeasterly direction, the 

 strata varying in strike from W. 35° I:^. to IST. 15° E., and dipi)ing west- 

 erly and southwesterly at angles of from 25° to 45°, even becoming more 

 steeply inchned toward the southwest foot of the mountain. The section 

 observed at this locality exhibits the following series of strata, the ac- 

 companying diagram connecting the two great spur-branches of this 

 part of the range along a line E. N. E. and W. S. W. 



Section across the Blaclcfoot Range through BlacJcfoot Peal', Station VI. 



1. Bluish limestone debris in sloi^es of ravine southwest foot of Black- 

 foot Peak. 



2. Intensely hard dark bluish-gray hornstone, standing nearly vertical, 

 and crossing the foot of the mountain in a N. W. and S. E. direction. 

 The ledge sometimes weathers in two parallel combs, perhai)S 10 feet in 

 thickness, and which may be traced some distance, appearing like a dike 

 thrust u]) in the surface of the slope. 



3. Bulf siliceous debris, or quartzitic fragmentary sandstone. 



4. Bluish-gray siliceous limestone, containing small crinoidal columns; 

 a heavy ledge, dipping sonthwestward at an angle of 45°. 



5. Buft' and bluish, fi-agmentary siliceous beds or quartzitic sandstone, 

 forming a heavy bed. 



(J. Bluish-gray, heavy-bedded, spar-seamed, cherty limestone, inter- 

 laminated with buft" siliceous layers, containing obs<;ure traces of fossils, 

 Spirifer^ Uemipronites, Athijris. This set of beds rises up into the sum- 

 mit of Station VI, where they incline at an angle of 35°, 8. 35° W. At 

 a lower level on the northwest spiu", the same beds dip 45°, W. 15° S. 



