174 OARBONIPEEOUS FORMATIONS AND FAUNAS oK COLOKADO. 



or I'cnuuui, !uul Triiissu'. There are one Devonian, one Carboniferous, I wo I'ermian, 

 and one Triassie .section, which it will be desirable to consider. Tiie Devonian, Car- 

 boniferous, and one of the Permian sections form, with the Silurian, a single con- 

 tinuous series. The other Permian section is probably continuou.s with the Triasssic 

 and with one of the Jurassic .sections, and was made at a different locality from the 

 lif-si. Instead of being equivalent, I think Peale's two Permian sections are much 

 nu)r(> likely to be nearly consecutive, the .second being above the first, but over- 

 lajipiii^-. il may be, to some extent. I have quoted Peale's .sections in full in another 

 place, and discussed their relations. 



Above the beds which Peale refers to the Silurian occur black, flinty limestones 

 with pieces of pyrite and fragments of Spirifer or Spiriferina. This is succeeded 

 by a space probably filled mainly by limestones, the entire thickness being esti- 

 mated at from 1,000 to 1,500 feet. The black, fiint}^ limestone is without much 

 doubt the Leadville limestone, but probably not the entire thickness can be assigned 

 to that formation, which is onlj' 350 feet thick at A.spen and 200 feet thick in the 

 Tenmile district. After an interruption of 15 feet of trachj'tic rock, the .section 

 proceeds in an upward direction, with a space of 408 feet filled mainh' with shale 

 and sandstone, and having a limestone at the base, from which some fossils were 

 obtained that seemed to indicate Pennsylvanian time. Aviculopecten, Pleurop>harus, 

 and an Avimda or Bakexmllia are cited. The middle or upper portion of this series 

 of pooily exposed beds probably belongs with the Maroon formation. The limestone 

 at the base, together with those below, would then represent the Leadville and 

 AYeber formations, so that the dividing line between the Leadville and the Weber 

 and between the Weber and the Maroon formations can not be ascertained. At all 

 events, the calcareous beds of the Leadville and the Weber at this locality must 

 aggregate about 1,500 feet, more or less. This is more like the Aspen section, where 

 these two formations amount to 1,350 feet, than the Tenmile district, where they 

 only measure 500 feet. In Tilden's section at lied (^lifl' also they have a combined 

 thickness of 1,560 feet. The remainder of the Carboniferous section above the por- 

 tion supposed to represent the Leadville and Weber limestones amounts to about 

 2,400 feet. The Permian section, which is continuous with it, is 1,276 feet 

 thick. Together the two series comprise 3,676 feet, of about the same character 

 of rock, and can safel}' be taken as part of the Maroon formation. The ''Car- 

 boniferous'' beds consist of greenish, brownish, white, gray, red, reddish-brown, 

 and pink sandstones, which are sometimes conglomeratic and more or less 

 intermingled with shaly beds. The Permian consists of gra3' sandstones and 

 white conglomerate, with about 10 feet of lilue limestone. The other Permian 

 section consists of a lower portion 700 feet thick, which probably belongs in 

 the Maroon conglomerate, and an upper portion 500 to 800 feet thick, which I think 



