STANTON, UPPER CRETACEOUS STRATIGRAPHY 67 



more than 300 feet above the Eagle sandstone and hence should 

 be in the equivalent of the Claggett formation. Or, to locate 

 it more accurately, according to Mr. Stebinger it is immediately- 

 above the horizon of a thin coal which he has traced down the 

 creek from the ''Alhson mine" a few miles northwest. 



Now the marine fossils found at this place belong to the fauna 

 which occurs in the sandstones of the Claggett formation at 

 its type locality and include among the more abundant and con- 

 spicuous forms Tancredia americana, Cardium speciosum, Mactra 

 formosa, etc. This is the fauna which in the past Meek, White, 

 Stanton, and others have called a typical Fox Hills fauna because 

 these conspicuous and abundant forms — the dominant species as 

 Prof. H. S. Williams calls them — ^do recur in the Fox Hills sand- 

 stone at the top of the Cretaceous colunni. 



This recurrent fauna when it reaches the Fox Hills is, of course, 

 not absolutely identical with the sandstone fauna of the Claggett, 

 but there are enough conspicuous, identical species to make iden- 

 tification of the horizon uncertain unless the collections are com- 

 plete or the stratigraphic details fully known. Recurrent faunas 

 are often troublesome and embarrassing to the stratigraphic 

 paleontologist and still more so to the stratigrapher who is not 

 a paleontologist. It is even difficult to prove that the fauna is 

 recurrent at a higher horizon when the two localities are as far 

 separated as central Montana and the middle of South Dakota, 

 as they are in the case of the type localities of the Claggett and 

 the Fox Hills, although the stratigraphic position of the Claggett 

 was determined in 1903 independently of the evidence of that 

 particular fauna and in contradiction of the interpretation that 

 had been placed on it. There are also many localities now known 

 where the stratigraphic position of the fauna in question, at one 

 or the other of the two horizons, is well determined. For these 

 reasons the argument set forth in a recent article by A. C. Peale^" 

 that the upper sandstones of the Claggett are identical with the 

 Fox Hills is altogether fallacious in so far as it is based on litho- 

 logic and faunal resemblances. Nevertheless it was gratifying 

 to find this Claggett-Fox Hills fauna in the normal position of 



2» Jour, of Geology, 20: 530-549, 640-652, 738-757, 1912. 



