INTRODUCTORY REMARKS. 



149 



placed the total thickness of the strata above water at Alum bluff, at low 

 stages of the river, at 63 feet, others at 125 feet. The earlier observers 

 regarded the clay above the Chesapeake marl as lignitic, which led to 

 its correlation with other lio^nitic beds to which attention has been 



Figure I.— Map of Portions of southicestern Georgia and central western Florida. 



directed. Mr Foerste, however, pointed out that the principal source 

 of the j^hytogene remains of this locality is in the Alum bluff sands. 

 The pecteniferous marl of Rock bluff had been referred to the nevrer or 

 Chesapeake Miocene, and its most prominent fossil wrongly identified. 



