236 Annals of the Carnegie Museum. 



been broken, and on the northwest side are the masses themselves, 

 standing lower than the cliffs on the opposite side. The depression 

 is thickly covered with grass, shrubs, small trees, and other vegetation. 

 On account of the scarcity of timber here, the heaviest of it has been 

 taken away. The trees are principally elm and ash. Outside the 

 terrace is a belt where the nodular (Oreodon) and upper beds have 

 literally " slidden all over" the lower beds, and the blocks and large 

 and small masses of the former lie at nearly all angles on the latter. 

 At first the strata have the appearance of having been greatly dis- 

 turbed by orogenic movements. The dislocated masses are thickest 

 near the bluffs, but remains of the pink nodular strata are found at a 

 considerable distance out on the flat. In one place there is a butte, 

 which lies at a considerable distance from the bluffs, and at a lower 

 level than the corresponding beds in the bluffs. It is seventy feet or 

 more in height, composed of strata of the Oreodon beds and overlying 

 shales, which are horizontal in position. This may be in its original 

 position, as it is difficult to see how it could have moved to this place 

 and still retained its normal horizontal position on the lower beds. As 

 one goes farther from the bluffs all traces of the middle beds grad- 

 ually cease and only the lower beds appear. The latter form a flat, 

 which in some places is cut by gullies, while other portions are 

 interrupted by peculiar mounds with rounded tops and abrupt sides. 

 Sometimes in the fading light these suggest huge mammoth-like 

 creatures feeding on the distant plain. There are some indications 

 that the Oreodon beds are not exactly comformable with the Titano- 

 therium beds, but that the former sometimes occupy slight depressions 

 in the latter ; but this was not determined with certainty. In one or 

 two places the strata appear to have a true dip. In an exposure on the 

 north side of the Little Bad-lands the lower nodular layers of the 

 Oreodon beds incline toward the east. 



The Lower White River (^Titaiwtheriin)i) Beds. — The lowest ex- 

 posure of the Titanotherium beds are gray sand and clay. A little 

 higher they are more sandy and often have a peculiar cross-bedded 

 appearance, caused by the fact that the coarser material is arranged 

 obliquely. This condition, which suggests delta-deposits, appears in 

 the sides of the hog-backs or dome-shaped mounds with nearly per- 

 pendicular sides, which stand on the bare flat areas. In the lower 

 part of these beds are dark iron-stained concretions, many stream- 

 worn quartzyte and granite pebbles, and occasional fragments of bones. 



