RECAPITULATION OF PALEOZOIC FORMATIONS. 143 



South of the Arkansas border — that is, over almost the whole of the Sangre de 

 Cristo region — the Sawatch, together with the other earh' Paleozoics, is lacking, per- 

 haps through nondeposition, but more probably, I believe, through erosion prior to 

 the deposition of the Arkansas sandstone which rests for the most part upon the 

 granitic foundations of the range. However, on the west side of the Sangre de 

 Cristo Range, in the vicinity of Culebra Peak, in an area mapped by Endlich as 

 Arkansas sandstone, the Van Diests have recorded the occurrence of beds which 

 probably represent both the Sawatch quartzite and the Yule limestone. 



The identification in this case, though based only upon lithologic character and 

 geologic position, is fairly conclusive, and this isolated occurrence makes it not 

 improbable that similar disconnected areas of older Paleozoics maj^ be discovered in 

 this and other regions where they now seem to be wanting. 



In the Uinta Mountain region the section is so different from that of central 

 Colorado that a comparison of the lithologic sequence without further means of 

 paleontologic correlation is hazardous. The great formation which Powell desig- 

 nates the Red Creek quartzite must belong to the series now called Algonkian. This 

 is immediately overlain b}- the Uinta sandstone. If the recognition of this forma- 

 tion by geologists of the King survey as the equivalent of the Weber quartzite of 

 the Wasatch Mountains be correct, since the latter is of Pennsylvanian age, the Cam- 

 brian would appear to be absent in the Uinta Mountains. Yet, as the Uinta sand- 

 stone is so much thicker than the Weber formation, it is possible that its base may 

 comprise an undifferentiated series belonging to the Sawatch quartzite, and even that 

 other pre-Cai'boniferous horizons may be represented there by siliceous equivalents. 

 On the whole, however, it seems to me probable that the Uinta sandstone comprises 

 Carboniferous strata above, with probably a considerable thicknesss of Cambrian 

 beds in its lower part. Unfortunatelj^, about the exposures north of Eagle River, 

 whose conduct might afford a clue to their relation with the Uinta section, very little 

 is known. 



Along the Front Range the Paleozoic are largely concealed by the Red Beds, 

 though I have no doubt that they are present somewhere to the east, under the 

 plains. The Camlirian outcrops but scantily along the Front Range, and it is no 

 longer the white quartzite which formed such a distinctive feature of the Sawatch, 

 but is composed largely of reddish sandstones, resembling rather the upper beds of 

 the Sawatch and the Cambrian of the Black Hills. In the Pikes Peak quadrangle 

 Cross describes it as follows: 



"No Cambrian formation is represented upon the map, although it is probable 

 that a small thickness of quartzite and of cherty limestone below the Manitou Silu- 

 rian limestone belongs to that period. In Manitou Park and near Manitou Springs 

 brachiopod shells, Lingulejns and Oholella, have been found in quartzites beneath 



