INTRODUCTION 



BRIKF VIEW OF. THE TERTIARY FORMATIONS OF THE 

 UNITED STATES. 



SVN. Supercretaceous group; DvlaBcche. Superior order, Conybeare and 

 Phillips. Terrains ize'miens tfial'asiques, A/. Brongnidrt. 



' Each of these great classes is again, divided into a number of 

 subordinate deposits, denominated formations, of which the 

 Tertiary appears to possess three, called, in Europe, the Upper 

 Marine, London Clay and Plastic Clay formations. The last 

 two of these names are very exceptionable, the one being local 

 and the other far from descriptive. . It is therefore proposed in 

 the following work to speak of the three formations according 

 to the order of their succession, and, at the suggestion of a 

 friend, to call them the Upper Tertiary or Upper Marine, the 

 Middle Teitiary and the Lower Tertiary. The relative posi- 

 tion of these different formations will be best conveyed by the 

 the following diagram ; merely premising that we are fully aware 

 of the objections which have been urged against these divisions, 

 and that we adopt them in the absence o.a better nomencla- 

 ture, as possessing a very convenient,' and, we believe, a natural 

 adaptation to the strata. 



Cha ractcrhtic foila. 



Localitie*. 



[23] 



