Douglass : A Geological Reconnaissance. 281 



Other Eocene Deposits. 



On Sage Creek northeast of Lima are exposures of Tertiary deposits, 

 which, judging by the fragmentary mammalian fossils, appear to be 

 partly of Eocene, partly of Oligocene, and partly of Miocene age. 

 Those supposed to be of Eocene age are somewhat different in appear- 

 ance from any other Tertiary deposits which I have seen. They are 

 composed of sands and clays, and are distinctly stratified and banded. 

 They contain remains of logs, which have been replaced by calcite 

 crystals, calcified twigs, and vertical cylindrical cavities lined with 

 crystals of quartz and calcite. One large geode, composed of encrusted 

 crystals of quartz, crystals of calcite, etc., which has broken in pieces 

 and strewn the rocks below, was found in the small exposures of this 

 formation.'" 



Oligocene Deposits. 



The restricted areas of Oligocene deposits, which overlie the Fort 

 Union beds in western North Dakota, have not, so far as I am aware, 

 been fully described. Professor Cope collected some fossils in the 

 state in 1883. In a letter written from Sulley Springs is the following : 

 "The beds, which are unmistakably of the White River formation, 

 consist of greenish sandstone, and sand-beds, of a combined thickness 

 of about 100 feet. These rest on white calcareous clay, rocks and 

 marls, of a total thickness of 100 feet. These probably also belong to 

 the White River epoch, but contain no fossils. Below this deposit is 

 a third bed of drab clay, which swells and cracks on exposure to 

 weather, which rests on a thick bed of white and gray sand, more or 

 less mixed with gravel. This bed, with the overlying clay, probably 

 belongs to the Laramie period, as the beds lower in the series cer- 

 tainly do."" 



The following is the list of fossils given by Cope : 



Rhineastes sp. nov. 



Aminurus sp. nov. 



Trionyx, 2 species. 



Styletnys. 



Castor. 



Galecynus gregarius. 



Hoplophoneus, 2 species. 



^*For an account of the mammals of these beds see " New Vertebrates from the 

 Montana Tertiary," Annals Carnegie Museum, Vol. II, No. 2, 1903, p. 155. 

 '^'^ Proc. Amer. Philos. Soc, XXI, Oct. 30, 1883, p. 216. 



