HATPEN.] GEOLOGY WHITE EIVER GROUP. 25 



from a distance, exactly the appearance of the ruins of an ancient city. 

 The difBcnlty the traveler meets with in finding his way through this 

 interminable labyrinth caused the Indians to call it, in their own 

 language, the Bad Grounds ; hence the French name, Mauvaises terres, 

 applied by the Canadian voyageurs in the employ of the fur-companies. 



" The vertebrate remains found in these beds belong to 'the genera 

 Oreodon, Agriocliarus, Poebrotheriiim, Le^jtomei-yx, Leptanclienia^ Pro- 

 tomeryx, 3Ierycodos, Titanotherium, Lepto cheer us, Hyracodon, Entelo- 

 don, Palceochcerus, Ekinoceros, Steiieojiber, Macliairodos, Anchitherium, 

 Hyopotamus, Hycenodon, Ischyromys, Paloeolagus, Eumys, Testudo, etc., 

 etc. The affinities of these fossils, as has been shown by Professor 

 Leidy, clearly establish the Miocene age of this formation. 



" Comparatively few invertebrate remains have yet been found in the 

 "White River group. They consist of one species of Helix, one or two of 

 Limncea, a small Physa, two or three small species of P/owor&is, etc. No 

 fossil leaves nor beds of lignite have been met with in it, and all the 

 animal remains, as may be seen from the foregoing list, are terrestrial 

 and fresh- water types. The Loup River beds consist mainly of incoher- 

 ent materials, and were evidently deposited after the upper surface of the 

 White River group had been worn into ravines and other depressions. 

 It occupies much of the surface of the country in the region of the Loup 

 Fork and Platte River, and extends far south of the latter stream. 



"The vertebrate remains from it described by Professor Leidy belong 

 to the genera Megalomeryx, Procamelus, Cervus, Bhinoceros, Mastodon, 

 Elej}has, Hipparion, Merychippus, PJquus, Castor, Felis, Canis, Testudo, 

 etc., many ot which are very closely allied to recent species, A few shells 

 of the genera Helix, Physa, etc., apparently identical with living spe- 

 cies, have also been found in these beds. All the species of vertebrate 

 and other remains yet found in them are distinct from those occurring 

 in I he White River group and beds below, and they have not yet afforded 

 any brackish or marine types of any kind. 



"When we take into consideration the position of this formation above 

 the well-marked Miocene White River group, and the relation of its 

 organic remains to Pliocene and recent species, there is little room for 

 doubting the correctness of its reference to the horizon of the Pliocene 

 of Europe. 



" The extracts which I have given are sufiicient to show the opinions of 

 a most excellent paleontologist in regard to the age of this group as 

 interpreted from the invertebrate fossils." 



Let us for a moment glance at the testimony of American vegetable 

 paleontologists. W^ithout quoting again, I will simply refer the reader 

 to the interesting report of Dr. J. S. Newberry on the Cretaceous and 

 Tertiary plants collected by me during the expedition to the Yellowstone 

 and Missouri Rivers, during the years 1859 and 1860, a portion of which 

 was reprinted in the Annual Report of Wyoming, 1870, commencing at 

 page 94. It will be seen that Dr. Newberry regarded these fossil plants 

 as not only of Tertiary age, but Middle Tertiary, or Miocene. In an in- 

 teresting memoir published in the Annals of the Lyceuui of Natural 

 History, in 1807, Dr. Newberry remarks : 



" By far the largest representation of our Tertiary flora is, however, 

 contained in collections made by Dr. Hayden on the Upper Missouri, of 

 which the greater number of species are described in the present mem- 

 oir. These plants are from the lignites proved by the associated fossils 

 to be of the Miocene age. They v/ere collected at various points on the 

 Missouri River, at Port Clarke, at Red Spring, thirteen miles above, at 

 Fort Berthold, at Crow Hills, one hundred miles below Fort Union, at 



