L.ILX OLITES IX SOUTI/KASTERX COLORADO 8 I / 



indicate the presence of laccolitcs of some magnitude. The fol- 

 lowing month I returned to the locality in company with Mr. F. H. 

 Newell, and we spent a week in local surveys and studies. A con- 

 tour map of the locality was made, the thicknesses of the sedimen- 

 tar\- formations were measured, and all outcrops were platted. 

 Vi\ combining these data it was found possible to construct an 

 approximate contour map of the deformation of the upper strata, 

 and thus estimate the total volume of the intrusions. 



The following is the sedimentary section as determined by 

 Mr. Newell : 



5. Olive, purple, and pink shales, with beds of fine-grained yellow- 

 sandstone, and one or more bands of concretionary impure lime- 

 stone. The sandstone contains large, beach-rolled, silicified logs. 

 From the upper shaly layers were obtained invertebrate fossils, 

 recognized by Mr. T. W. Stanton as of Dakota age. The top of 

 the formation was not seen, --_.--. 100 ft. 



4. Sandstone, fine-grained, chiefly massive but partly bedded, of 

 variable color. On the east side of the dome all zones of the 

 sandstone are bright red, and this is probably their normal color; 

 but the different layers, as they approach the base of the Neocene 

 sands, become vellow, and in some places white. On the south- 

 western slope of the dome, a shale forty or fift}' feet thick parts 

 the sandstone into two groups, of which the lower retains the 

 characters just described, while the higher has a prevailing dull 

 vellow color, and is in part vitreous, as though modified b}' igne- 

 ous intrusion. A similar distinction was seen at the north, where 

 most of the upper member has the character of quartzite, and the 

 vellow color is replaced by gray, ------ 380 ft. 



3. Brick-red shales, arenaceous at top and passing by gradual tran- 

 sition into Xo. 4. Soft and easilv eroded, except in the immedi- 

 ate vicinity of igneous masses, - - - - - - - 150 ft. 



2. White limestone, - - - - - - - - 5 to 10 ft. 



I. Yellow, red, and orange, thin-bedded shales and sandstones. The 

 shales probably exceed the sandstones in thickness, but being 

 largely arenaceous, thev assume the character of sandstones in 

 the vicinitv of igneous intrusions. The bottom of the series was 

 not seen, - - - - - - - - - - -100 ft. 



Total, ---------- 740 ft. 



