INSTITUTE OF SCIENCE, PHILADELPHIA. 2O9 



immediately reach the Floridian peninsula ; but, whatever their migrations, it 

 is certain that during the Middle Pliocene they made their appearance in that 

 region. Their bones, sandwiched between fossiliferous rocks of Pliocene age, 

 establish this fact beyond controversy. 



The invertebrates appear — in Florida, at least — to have flourished peace- 

 fully, and the extinction of some of the most conspicuous forms of the fauna 

 appears to have been brought about by a movement in elevation which raised 

 their favorite shallows above the sea — an elevation not necessarily of many 

 feet in altitude. At all events, a majority of those species which live prefer- 

 ably in moderate depths of water, as opposed to littoral forms, still persists in 

 similar situations, unmodified to any notable extent. 



The orogenic independence and singular tranquillity of the area which 

 originally formed the island of Florida, contrast strongly with the disturbances 

 in elevation or depression of which both continental and Antillean geology 

 give evidence. It would seem almost as if Florida had rested on the axis of 

 the disturbances, and the tilting northward and southward been minimized at 

 that point. 



For the beds exhibited in South Carolina along the Waccamaw, above 

 the Cretaceous marl, as sectionized by Tuomey and Johnson, the name of 

 Waccamaiu beds may be adopted. For those which are found along the 

 estuary of the Neuse River the local Indian name of Croatan beds may be 

 used. Both, as will subsequently appear, may be referred to the Floridian 

 group or epoch. The relations of our later Tertiaries may be broadly sum- 

 marized as follows : 



Later Eocene. 



Vicksburg group (Jackson, Vicksburg and Salt Hill formations). 



Ocala group (Nummulitic beds of Florida). 



MIOCENE. 

 Chipola Epoch. 

 Chattahoochee group (Hawthorne and Ocheesee beds). 

 Tampa group (Shiloh marl, Tampa and Chipola beds). 



Chesapeake Epoch. 

 Chesapeake group (Maryland, Virginia, etc.). 



Grand Gulf group (Grand Gulf beds, Altamaha Grit, etc. — Epoch of ele- 

 vation begun and in progress). 



PLIOCENE. 

 Floridian Epoch. 

 Lafayette group (Lagrange beds. Orange sand, etc. ; culmination of 

 elevation). 



Floridian group (Caloosahatchie, De Soto and Waccamaw beds, etc.). 



