424: X. H. DARTON — STRATIGRAPHY OF THE BLACK HILLS, ETC 



ticall} r all of the formation, but it thins out to the southward, and is 

 absent for some distance along the foot of Greenhorn mountain. At the 

 south end of this mountain appears a similar series of rocks which Mr 

 R. C. Hills named the Badito formation. Tt comprises an upper mem- 

 ber about 100 feet thick, generally massive or thick bedded, but some- 

 times shaly on the weathered surface and corresponding to a part of the 

 Fountain formation. The lower half consists of about the same thick- 

 ness of very coarse conglomerates of brownish red color. This series 

 appears again in the Culebra range, where it expands to a great thick- 

 ness and includes limestones which appear near La Veta pass and extend 

 southward into New Mexico. This area was described in considerable 

 detail by Endlich, of the Hayden survey, who mapped the lower por- 

 tion of the series as " Lower Carboniferous," and several thousand feet 

 of overlying Mesozoic and Eocene beds as Upper Carboniferous. In 

 1902 Mr Willis T. Lee* collected fossils in this district, mostly from the 

 lower beds of the series not far above the granite. They were identified 

 by Dr Stuart Weller and found to be Upper Carboniferous. Forty-six 

 species were represented. The rocks consist of a variable alternation of 

 coarse gray to red sandstones, shale, and limestones. 



A small collection of Upper Carboniferous fossils was also obtained 

 from the western slope of La Veta pass, 5 miles above Placer, in a suc- 

 cession consisting of sandstones, limestones, shales, and conglomerates 

 similar to those above described. 



It was found by Mr Lee that the Millsap and underlying limestones 

 are not present in the Culebra range, although possibly there ma)' be 

 small outliers of them in portions of the range which he did not visit. 

 The strata overlying the section given above consist of several thousand 

 feet of red and gray sandstones, mostly coarse, extending to the base of 

 the Morrison formation and representing the Fountain series. 



SUNDANCE FORMATION 



The Sundance formation extends only a few miles into Colorado from 

 the northward, finally ending by thinning out. Doctor Hayden f found 

 fossils, u Ostrea and fragments of Pentacrinus asteristicus, on Box Elder 

 creek, in yellow sandstones and clays," with scattered layers or nodules 

 of limestone. He suggested that the limestone sometimes found at the 

 base of the Morrison formation may be a representative of the marine 

 Jurassic, a suggestion based on its similarity in character and relations 

 to a limestone on the Laramie plains, which contains Apiocrinites. As 

 similar limestones exist in typical Morrison beds northward, where the 



* Carboniferous of the Sangre de Cristo Range. Jour. Geol., vol. 10, 1902. pp. 393-396. 

 fF. V. Hayden : Third Ann. Rept. U. S. Geol. and Geog. Survey Terr, (for 1869), p. 119. 



