210 



THE GEOLOGICAL HISTORY OF PLANTS. 



Miocene. They are also undoubtedly continuous with 

 the Fort Union group of the United States geologists on 

 the other side of the international boundary, and they 

 contain similar fossil plants. They are divisible into two 

 groups — a lower, mostly argillaceous, and to which the 

 name of " Bad Lands beds " may be given, from the " bad 

 lands " of Wood Mountain, where they are well exposed, 

 and an upper, partly arenaceous member, which may be 

 named the Souris Eiver or Porcupine Creek division. 

 In the lower division are found reptilian remains of Upper 

 Cretaceous type, with some fish remains more nearly akin 

 to those of the Eocene.* Neither division has as yet 

 afforded mammalian remains. 



The western area is of still larger dimensions, and ex- 

 tends along the eastern base of the Kocky Mountains from 

 the United States boundary to about the 55th parallel of 

 latitude, and stretches eastward to the 111th meridian. 

 In this area, and more especially in its southern part, the 

 officers of the Geological Survey of Canada have recog- 

 nised three divisions, as follows : (1) The Lower Laramie 

 or St. Mary River series, corresponding in its character 

 and fossils to the Lower or Bad Lands division of the 

 other area. (2) A middle division, the Willow Creek 

 beds, consisting of clays, mostly reddish, and not recog- 

 nised in the other area. (3) The Upper Laramie or 

 Porcupine Hills division, corresponding in fossils, and to 

 some extent in mineral character, to the Souris River 

 beds of the eastern area. 



The fossil plants collected by Dr. G. M. Dawson in 

 the eastern area were noticed by the author in an appen- 

 dix to Dr. Dawson's report on the 49th parallel, in 1875, 

 and a collection subsequently made by Dr. Selwyn was 

 described in the " Report of the Geological Survey of 

 Canada" for 1879-80. Those of the western area, and 



* Cope, in Dr. G. M. Dawson's " Report on the 49th Parallel." 



