8T.J0HX.] SECTION IN CARIBOU RANGE. 397 



110. Eed earth. 



111. Eruptive rock, similar to No. 103 ; forms a heavy ledge, dipping 

 at a steep angle soutliwestward. 



112. Bluish, sixir-seamed limestone, exposed space 20 feet, but much 

 broken np, obliterating the planes of bedding; contains obscure remains 

 of a very small robust or gibbose form of Gasteropod, resembling a form 

 occurring elsewhere in horizons provisionally referred to the Laramie 

 formation; but, at the same time,it is difficult to distinguish it from very 

 similar forms, both in appearance and condition, prevalent in Jiu-assic 

 strata in the same region. 



113. Gray sandstones and red shales, exposed in space perhaps 200 

 yards across. 



111. Eruptive or intrusive porphyritic ledge, like 111, but much broken 

 up ; exposure 25 yards across. 

 115. Gray and drab, partially metamorphosed shales, space 60 yards. 

 IIG. Soft gray sandstone, GO feet exposed; dip 30°, S. 45° TV'. 



117. Eed shales, 20 yards across. 



118. Eruptive ledge, like 111, much broken np. 



119. Gray sandstone and chocolate-colored shales, with porphyritic 

 trachj-te debris in the surface, and bluish-gTay arenaceous indurated or 

 metamorphosed shales above, space 100 to 150 yards ; dip 45° south west- 

 Trard. 



120. Eruptive ledge, like 118. 



121. Bluish, fine-grained, ripple-marked, indurated arenaceous shales, 

 interbedded with brown chocolate-colored shales, all more or less indu- 

 rated or metamorphosed, exposed 30 feet, space 100 yards. 



122. Eruptive ledge, like 118, 15 feet exposed. 



123. Metamorphosed variegated shales, 30 feet exjposed. 



124. Eruptive intruded ledge, like 122. 



125. Bluish, chocolate-colored, laminated slaty shales, much changed 

 by contact with intrusive volcanic material ; dip 45° to 50°, S. 45° AY. 



126. Eruptive ledge, like 124, space 30 yards. 



127. Slaty shales and fine-grained bluish gray sandstone, space 30 

 yards ; dip 35°, S. 45° ^Y. 



128. Eruptive ledge, like 126, space 15 yards. 



129. Brittle drab slates or metamorphosed shales, including below 

 two thin sheets of iutrusive volcanic material like 128, space about 200 

 yards. 



130. Dark brownish gray sandstone and conglomerate. 



131. Several ledges of eruptive intrusive matter, hke 128. exposed high 

 np on spur, the crest of which for several hundred yards is strewn with 

 debris of similar rock, with obscure exposures of highly metamorphosed 

 drab and blue-green mottled slaty shales. In the summit of the outly- 

 ing dome by which the spur attaches to the saddle southeast of the 

 main summit, there appears a ledge of dark bluish hornblendic trachyte, 

 much broken up, so that its character may not be readily determined — 

 whether a dike or intrusive mass — and so with other exposiu-es of these 

 volcanic materials. 



On the northwest side of Station XXVIII the mountain is broken 

 down precipitously into a little amphitheatre, half environed by clift's 

 and talus slopes, in which a section showing a vertical thickness of 

 several hundred feet of sedimentary and intrusive ledges may be advan- 

 tageously studied. Although the direct connection could not be traced, 

 it is presumed that the volcanic intrusive ledges wliicli appear in the 

 amphitheatre walls are the same as the blindly-exposed ledges last re- 

 ferred to in the uj)per crest of the spur next southeast, the strike of the 



