FREE INSTITUTE OF SCIENCE 



I S6l 



TERTIARY FAUNA OF FLORIDA 



deposits of the Chattahoochee, which are their time equivalent" (p. 17), and 

 " The underl3'ing division of the Grand Gulf ... its position is identical 

 with that of the Chattahoochee limestone of Mr. Langdon, and there is no 

 room for any reasonable doubt about their identity in age" (p. 106).* Having 

 cooperated with Dr. Smith by studying his collections of fossils and furnish- 

 ing data as to their identification (as he generously acknowledges in the work 

 cited), the writer can only express his concurrence in the learned Doctor's 

 opinion. 



There has, however, as in so many other cases, been some confusion in the 

 literature in regard to the so-called " Grand Gulf beds," due to too great in- 

 clusiveness of beds lithologically similar but which by their contained fossils 

 are shown to belong to different horizons, some even widely separated. Mr. 

 Langdon f rather amusingly complains that the authorities were at that time 

 "' apparently more interested in making long checklists of fossils and describing 

 new species than in recording the character of the strata from which the fossils 

 were collected." Some, at least, of the authorities have done their best to 

 " record the character of the strata," but it has been far more necessary to 

 obtain a careful and complete census of the fauna in each stratum than to 

 describe any number of beds of marl lithologically. 



With beds composed of similar materials and often from the remanie sub- 

 stance of the bed preceding, it is practically impossible to form any sound 

 judgment of the geological position of any given stratum in that region with- 

 out a knowledge of its fossils. If we were so fortunate as to possess a full 

 knowledge of the extinct faunas of the coastal plain nothing would be easier 

 than to settle its geology once and for all time to come. Pending an approxi- 

 mate knowledge of those faunas we can only struggle along, making our check- 

 lists, describing the new forms, and working towards the desired end. 



The Grand Gulf sandstone was named by Wailes,! and its typical outcrop 

 is at Grand Gulf, Claiborne County, on the banks of the Mississippi about a 

 mile below the mouth of the Big Black River and immediately above the town 

 of Grand Gulf, where it forms a bold promontory against which the current 

 sets in great force, creating a dangerous whirlpool or eddy which gave name to 

 the place. A carefully detailed section and photograph of the Bluff are given 

 by Miss Maury in her thesis on the Oligocene of Europe and the United 



* Geol. of the Coastal Plain of Alabama, 1894. 



t Ibid., p. 375. 



t Agriculture and Geology of Mississippi, p. 216, 1854. 



