Douglass : A Geological Reconnaissance. 



283 



I 



while the upper portion is lower Oligocene. The eastern portion of 

 the butte is a much dissected ridge or line of buttes, which begins near 

 the middle of the eastern portion of the western ridge and trends to 

 the southeastward, leaving a basin between the two portions. The 

 eastern part is composed of lower, middle, and upper White River 

 beds. 



The following section is from the eastern slope of the eastern portion 

 of the butte. I did not find the contact here between the Fort Union 

 and the White River, but began measurement at one of the lowest 

 Oligocene exposures. This section reaches upward only to the basal 

 portion of the Upper White River beds. 



Section of White River Beds at White Butte, North Dakota. 



(From above downward.) 



9. Gray sand probably with a mixture of volcanic ash. 6 ft. 



8. Clay or other fine material 3 ft. 



7. Cream-colored fine sandy clay i ft. 



6. Nodular Oreodon beds, clay, gray to light cream- 

 colored on surface, darker cream-colored in- 

 side. Nodules brownish, cellular, sometimes 

 containing bones, especially in lower portion. 

 Beds sparingly fossiliferous from top to bottom. 

 Jctops, Ischyromys, PalcBolagus, Mtrycoidodon 

 culbertsoni, Leptoimryx evansi, Mesohippus, 

 Hyracodoii, Aceratheriuni, etc 35 ft. 



5. A band of rock which weathers gray on the sur- 

 face, becoming more nearly cream-colored 

 toward the top at the base of the Oreodon beds. 

 Some thin layers are very compact. Bones 

 black. Merycoidodon, e\.c '^S ^^■ 



4^. A mixture of hard and soft rock (silicious clay) 



weathering into tough, compact masses. 

 4^. Rock tough with one seam containing nodules of 



barite. 

 4«. Rock white or gray at bottom, with imperfectly 



horizontal fractures or division planes 25-30 ft. 



3. Yellowish sand with fine and coarse grains mixed 

 with clay and having a slightly saline (?) taste. 

 White on weathered surfaces. When the color- 

 Lower While ing matter and the fine clay are washed out it 

 River. leaves a very clean sand, composed principally 

 of clear quartz grains, which have been imper- 

 fectly rounded by the action of wind or water.. 80 ft. 

 2. Thinly and horizontally laminated clay, fine grit, 

 and gray sandstone. The lighter laminae are 



Middle White 

 River. 



