THE RELATIONS OF THE MIOCENE OF 

 MARYLAND TO THAT OF OTHER 

 REGIONS AND TO THE RE- 

 CENT FAUNA 



BY 



WILLIAM HEALEY DALE. 



The Director of the jMaryland Geological Survey having requested me 

 to prepare a chapter reviewing some of the relations of the Miocene in 

 M-aryland to that of other regions and to the recent fauna, and the per- 

 mission of the Director of the U. S. Geological Survey having been 

 kindly given, the following considerations are submitted. In pronounc- 

 ing judgment upon them it should always be borne in mind that the 

 stratigraphical relations of the more southern Miocene adjacent to that 

 of Maryland, especially that of Virginia and the Carolinas, are still very 

 imperfectly known, although the faunas of certain particular outcrops 

 have been quite fully enumerated. 



Before proceeding to the consideration of the local Miocene it will be 

 well to recall the origin and scope of this term and what it stands for in 

 European discussions of Tertiary Geology. 



In the subdivisions of the Tertiary instituted by Lyell and Deshayes 

 those faunas were denominated as Miocene which contain from 17 to 20 

 per cent of species which survive to the recent fauna. This definition, 

 corresponding to the idea of evolution in the characteristic faunas, still 

 lies at the foundation of our ideas of what constitutes a Miocene fauna, 

 though to a greater or less extent modified by differences of opinion as 

 to what constitutes a distinct species, and by a wider knowledge of modi- 

 fications of faunas due to temperature, migration and the various factors 

 which, taken together, form that group of influences which is denomi- 



