230 Annals of the Carnegie Museum. 



not produce any ill effects ; even the fine white sediment I did not 

 find particularly disagreeable. The water of a spring from the top of 

 the Fort Union beds, a little farther to the south on White Butte, was 

 dark with alkali. 



The next day Harry, the son of Mr. Roberts, ^nd I went south- 

 ward from Mr. Roberts' house about two and one half or three miles, 

 and ascended a branch of Sand Creek which comes from the eastward, 

 cutting through the western ridge of White Butte. The rocks along 

 the bottom of the ravine are the gray sandstones, shales, and lignites 

 of the Fort Union beds. These outcrop at several places on the 

 western base of the butte. Though the lower portion of the ravine 

 is in the Lower Tertiary, yet all along, the Later Tertiary beds appear, 

 capping the hills or ridges. On top and part way down the sides the 

 butte has a peculiar broken appearance. Blocks of sandstone are 

 scattered over the surface, making it look as if ice or snow had been 

 concerned in forming its peculiar topography. Perhaps part of this 

 appearance is due to landslides. The slope on the south side of the 

 ravine is thickly covered with brush, small timber, and other vegeta- 

 tion, well up toward the top of the butte. Near the head of the 

 canon, where it enters the ridge from the east, is the contact between 

 the Fort Union and Oligocene formations. A little below the con- 

 tact is a spring, the waters of which are dark, because of the presence 

 of alkali. Apparently the spring issues from a bed of coal. 



Starting from about half a mile to the east of the head of this 

 ravine, and separated from the main ridge of the butte by grassy hills, 

 a range of higher denuded hills (Plate XVII) or small buttes extends 

 two or three miles to the southeastward. Between these hills and the 

 main ridge, is an uneven grassy country, dissected by ravines and 

 gullies, where the branches of Sand Creek unite before passing through 

 the ravines in the western portion of the butte (Plate XXI). The 

 eastern hills consist of four or five sub-pyramidal mounds, with broad 

 white bases extending out in lobes and angles in every direction, and 

 with ridges connecting the higher elevations. There are also some 

 small outliers of the white material. These lower beds are the same 

 as those on the top of the main butte, though in the latter place they 

 have the appearance of reaching a greater elevation. Above the white 

 beds there are slopes or escarpments of a creamy color, and above 

 these are sandy beds weathering into slopes, which are interrupted by 

 abrupt scarps of sandstone. 



