STRATIGRAPHIC POSITION OF LANCE FORMATION 371 



[5423]. South of Moreau River about 7 miles above Thunder Butte P.O., 

 S. Dakota. 

 Sec. 35, T14N, R19E. Lower 4 feet of Lance formation. 



Thuya interrupta Newb. 



Sequoia nordenskioldi Heer 



Sequoia acuminata ? Lesq. 



Populus cuneata Newb. 



Viburnum marginatum ? Lesq. 



Leguminosites ? n. sp. 



Cyperacites sp. 



Monocotyledon — new 



It needs but a glance at the above lists to show how preponder- 

 ating is the Fort Union facies. 



CONVERSE COUNTY, WYOMING 



Although Converse County, Wyoming, is the type locality for 

 the Lance formation, and has been visited again and again by 

 geologists and paleontologists, it is still a perennial source of dis- 

 cussion and difference of opinion. From the first, difficulty has 

 been experienced in drawing the line between the highest marine 

 formation — the Fox Hills — and the overlying dinosaur-bearing 

 beds. The Fox Hills was estimated by Hatcher to have a thickness 

 of 500 feet, and consists of an alternating series of sandstones and 

 shales, with massive sandstones at the top which contain numer- 

 ous large concretions and a rich marine fauna of characteristic 

 Fox Hills species. The upper line was drawn somewhat arbitrarily 

 at a six-inch band of hard sandstone which was thought to separate 

 the fossil-bearing Fox Hills sandstone below from similar but sup- 

 posedly non-fossiliferous sandstones above. When Dr. Stanton 

 and I visited this region in 1896 we failed to secure evidence for 

 changing the top line of the Fox Hills as established by Hatcher, 

 though we did find four species of brackish-water invertebrates 

 in clays above a forty-foot bed of massive sandstone over 400 feet 

 above the highest fossiliferous Fox Hills horizon in that particular 

 section. 



So the question rested until 1909, when Messrs. M. R. Camp- 

 bell, T. W. Stanton, and R. W. Stone spent nearly a week in the 

 region. Their principal contribution to the knowledge of the 



