SINCLAIR— THE " TURTLE^OREODON LAYER." 459 



gether or in part, by channels of varying depth filled with coarse 

 greenish micaceous sandstone, which I take to be the equivalent of 

 the Metamynodon channel sandstone, as they occupy a position sirni- 

 lar to the latter. The nodules do not pass through the sandstones 

 or lie above them, but stop suddenly at the edges of the channels 

 and reappear beyond them, which can only be interpreted as erosion 

 subsequent to the deposition of the nodular zone ; but there are other 

 channels clearly contemporary with the " turtle-oreodon layer " and 

 wholly inclosed within it as observed to the east of Chamberlain 

 Pass, about 4.5 miles east of Scenic in the basin of Cain Creek, 

 where the lower levels of the " turtle-oreodon layer " may be diversi- 

 fied by zones of pale green lime-cemented concretions or hard green- 

 ish sandy clays cut by vertical joints into spherically weathering 

 blocks and separated horizontally by beds of soft clay. Further- 

 more, a well-defined green sandstone channel was here noted in the 

 upper part of the " red layer " itself. 



In Jackson County, in the vicinity of Cedar Pass near Interior, 

 along the south side of " The Wall," the contact of the " turtle- 

 oreodon layer" with the Titanotherium beds is somewhat doubtful 

 owing to the presence in both of greenish nodular zones which look 

 very much alike and to the local absence of fossils characteristic of 

 the Titanotherium beds. My measurements started somewhat arbi- 

 trarily at the top of a rather persistent bed of reddish clay above 

 which an Oreodon beds fauna occurs throughout a zone of reddish 

 and greenish banded clays 43 feet, more or less, thick with frequent 

 bands of nodules, greenish in color in the lower part and, at the top, 

 rusty and cellular, inclosing fossils and similar in every respect to 

 those described from the Big Badlands. At the Cedar Pass locality 

 the " turtle-oreodon layer " is followed by 58 feet, more or less, of 

 clay from which nodules are conspicuously absent, faintly color- 

 banded (red and green) and practically free from coarse material 

 except an occasional thin lens of sandstone. It will be noted that 

 this sequence of beds is somewhat dififerent from that found 40 

 miles or more farther west, but this is not an infrequent occurrence 

 in Tertiary continental formations. The remarkable thing is the 

 presence of the " turtle-oreodon layer " or " red layer " over such a 



