xu INTRODUCTION 



" The bones are invariably found in a stiff and extremely tenacious clay, 

 which occupies depressions on the higher knolls which rise here and there 

 above the general level, and usually near a pond, sink, or other depression, 

 still lower than the patch or strip of clay. Small and delicate bones are 

 rare, and the remains are usually the parts best adapted to resist destruction. 

 They are usually mixed without order, but parts of one skeleton have several 

 times been found in nearly their natural positions with relation to one 

 another.* 



" The geological relations of the deposit in every case examined were the 

 same. The country rock of most of Alachua County lies from two to six feet 

 below the present surface. It is composed of a rather soft limestone, pene- 

 trated in every direction by cavities that represent fossil shells, which have 

 been dissolved away, or, in rare instances, have been replaced by calc-spar or 

 chalcedony. Nodules of the latter, resembling true flint and having the same 

 conchoidal fracture, occur frequently, and often project from the surface where 

 it has been weathered. These rocks represent the Vicksburg beds of Conrad, 

 or the Oligocene of Heilprin, in which, however, two conformable series are 

 recognizable. The true Vicksburg, according to local geologists, is the rock 

 above described, over which is generally found another rock of similar consti- 

 tution, but much softer, with fossils loosely aggregated and entire, and largely 

 consisting of nummulites, orbitoidc^, and other foraminifera. This is locally 

 known as the ' rotten limestone,' but is not the same as the ' rotten lime- 

 stone' of Alabama and Mississippi, which is a much older rock. Heilprin 

 describes this ' Orbitoitic rock' as Vicksburg, but does not discriminate 

 between it and the first mentioned, though the latter has no nummulites in it 

 where I observed, and is lithologically distinguishable. Both appear to be 

 Oligocene. Above it he recognizes no marine deposits, nor have any been 

 described by geologists, as far as I know. Another rock, however, covers the 

 nummulitic rock in many places to a thickness of six or eight feet. This is 

 locally known as the 'phosphatic rock.' It occurs in place at the 'Devil's 

 Mill-hopper,' a remarkable sink about seven mi-les northwest from Gainesville, 

 on the Newnansville road. Lumps and boulders. of it occur on the higher 

 knolls eastward of this, but my opportunities did not admit of any attempt to 

 trace its limits. Information received from Mr. L. C. Johnson, of the Survey, 



*See Wyman, Florida Shell Mounds, p. 81. Some of these bones were mixed with the material 

 used by the Indians in building their mounds. 



