112 CAEBONIFEROUS FORMATIONS AND FAUNAS OF COLORADO. 



Ranyc. Itctwcen Colorado Springs and latitude, ■il'-, the lowest sedimentary rocks 

 found in contact with tiie metaniorphic Archean series are sandstones of the Triassic 

 age." In fact, however, the Hayden maps show Carboniferous rocks at the head of 

 "West Plum Creek, north of Colorado Springs, and there is reason to believe that 

 some of the Paleozoics still exist in the canyon of the South Platte. 



On the east side of the range, according to King, except for Tertiary overlaps, 

 there is a continuous chain of Paleozoic outcrops from the headwaters of Boxelder 

 Creek for 70 miles northward. Here the total Paleozoic series is limited to 850 feet. 

 Of this the lower 150 feet consist of red limestones and a reddish sandstone of varj'- 

 ing fineness. The upper portion consists of gray and blue arenaceous limestone and 

 calcareous sandstone. At the base of the upper division Upper Carboniferous fossils 

 occur. The species cited are Productus com, Productus semireticidatus, and Seminula 

 siildUita. King compares the rocks of this area, both as to lithology and to sequence, 

 with those of the Black Hills, and comes to the conclusion that the lower series here 

 is the same as the Primordial of that area. He believes, indeed, that into the 150 to 

 200 feet of beds below the horizon bearing Coal Measure fossils is condensed a com- 

 plete and conforuiable series of all the sedimentation of Paleozoic time prior to the 

 Upper Carboniferous. He says (p. 129): "Although we have actually found no 

 fossils in this horizon [the lower division], we feel the greatest confidence in asserting 

 that the whole Paleozoic series, from the Primordial to the Triassic, is here com- 

 pressed within the 850 feet." And again (p. 132): ''It maj" be predicted that sooner 

 or later the missing horizons between the Trias and the Cambrian are likely to be in 

 lai'ge part discovered, for in an ocean in which undisturbed deposition took place 

 from the beginning of the Cambrian to the close of the Mesozoic age no great period 

 of time would be likely to elapse without sedimentation, and it is to be predicted 

 that one after another the now missing main horizons will be identified, even if 

 reduced to extreme thinness." And also (page 138): '"Although they are barren of 

 fossils, from the downward sequence of beds, we have no doubt whatever that the 

 red sandstones, conglomerates, and quartzites underlying the Carboniferous lime- 

 stones belong, as we have correlated them, with the Primordial of the Black Hills 

 and Colorado Range. On the east side of Laramie hills the Paleozoic series reaches 

 its greatest compression, namely, 800 feet in thickness. There is absolutelj^ no 

 unconformity from the base to the summit. Therefore in this thin deposit is repre- 

 sented all the time from the Cambrian to the Trias, and yet organic life is only 

 represented by types of the Coal Measure epoch and the Permian." 



This hypothesis hardh' deserves consideration at this daj% but it is possible that 

 the lower beds of the section may be, as claimed by King, pre-Carboniferous. 

 Possibly the apparent nouconformitj- by overlap, cited by King, from the south 

 branch of Crow Creek, hj which the lower part of the section is missing and the 



