146 CAKBONIFEROUS FORMATIONS AND KAUNAS OK COLORADO. 



Quobi'c yi'oup. C'lDss also \isited Manitou Parle in connection witli the work of the 

 Leachillf inonogTaph. lie I'ouiul about 50 feet of i'C(l(lisli-))rown sandstone resting 

 upon tlu> Aroliean and siu-cceded by aliout 200 feet of calcaroous sandstones and 

 shales of variegated colors, red prevailing, which pass up into white or drab 

 limestones, sometimes containing chert secretions and alternating with shaly beds. 

 The lower beds furnished a Llngalepls related to L. pinniformis^ while from 60 to 

 77 feet above, an Ordovician fauna was obtained. The limestone is without doubt 

 the Manitou limestone, and the Cambrian is correlated, by Emmons, with the Lower 

 quartzite (Sawatch quartzite) of the Leadville area. In the Pikes Peak quadrangle 

 the Cambrian is reported as present, but in measures too thin to be given separate 

 representation upon the map. It consists of quartzite and cherty limestone. 



In Walcott's Canyon section no paleontologic evidence has been found to indicate 

 the presence of Cambrian, and there hardly seems room for it below the earliest 

 Ordovician strata. It appears, therefore, best to regard the Cambrian as absent at 

 this point. Walcott's section rests immediately upon the Algonkian, and Cross's 

 remark regarding the Harding sandstone, which I have quoted above, was apparently 

 made with I'eference to a case similar to this. 



No Silurian, under which term the Ha^^den geologists included also Cambrian, is 

 represented in the Hayden atlas along the mountain front south of the Canyon 

 outcrop, and at some points it is almost certainly wanting, as in Lee's section in 

 the Sangre de Cristo Range west of Trinidad, near the southern border of the 

 State. Indeed it is probably wanting over much of the range except its northern 

 portion, but E. C. and P. H. Van Diest have shown it and the Yule limestone to 

 exist on the west side of the Sangre de Cristo Range near Culebra Peak, as I have 

 already mentioned. The evidence is purely lithologic and stratigraphic, but the 

 occurrence seems to be authentic. The formation here is a white quartzite with a 

 basal conglomerate closeh' similar to. the typical Sawatch quartzite. 



In the San Juan region the Cambrian is probably represented by the 200 feet 

 of yellow, white, red, and brown quartzites occurring below the Ouray limestone. 

 These were tentativeh' placed as the lower member of the Devonian by Cross and 

 Spencer, but their Cambrian age is suggested by their lithology and stratigraphic 

 position when compared with other Colorado sections, and by the fact that Mr. Cross 

 has found among some talus very probabl}^ belonging to this formation, a block of 

 quartzite covered with linguloid shells which can apparentlv be referred to the genus 

 LinguleUa. 



In the valleys of Grand and Dolores rivers and many of their tributaries the 

 Cambrian appears to be unrepresented, the Carboniferous in some cases and in others 

 sediments of later age resting immediately upon the Archeau. 



Two of the most marked peculiai'ities of this formation are its diminution in 



