GENERAL SECTION ON THE CHATTAHOOCHEE. 603 



Feet. 

 41 — White calcareous sand, containin.^ a few obscure casts and an Osh-cea. The 



sand sometimes becomes irregularly indurated, and is the source of num- 

 bers of small lime springs ; forms the lowest part of the bluff at Fort 

 Gaines, Georgia, and in its uppermost 10 feet contains pockets of white 

 sand, enclosed by black clay, the clay resting in " potholes " in the lime- 

 stone; estimated at 200 



42 — Glauconitic sand filled with Gryphcea thhsce, Gabb ; Venericai^dia plani- 



cosia, and Crassatella tumidula 8-12 



43 — Gray, calcareous sandy clay, containing bowlders of clay and a few de- 

 composed shells of Gryphcza thirsm 15 



44 — White and lignitic cross-bedded sands, and sandy gray clay containing one 



or two ledges of " pseudo-buhrstone " 50 



45 — Dark-gray argillaceous sand, with few fossils and fragments of water-worn 

 clay balls. The lower part becomes more fossiliferous, containing Oste- 

 odes caulifera, Venericardia pianicosta^ and Gryphcea thirsce, etc 6 



46 — Greenish-gray, fine-grained calcareous sand; very firm, and holding de- 

 composed shells, mainly bivalves 6 



47 — Coarse glauconitic sand filled with very large shells of Ostrcea compressi- 

 rostra, Venericardia planicosta, and a small pecten resembling the species 

 occurring at Yellow bluff, on the Alabama 3 



48 — Cross-bedded yellow sands, the bedding planes being marked by streaks of 



gray clay 10 



49 — Yellow and gray sandy clays, containing occasional beds of Ostrcea compres- 

 sirostra and Gryphcea thirsce. The indurated ledges (seldom over two feet 

 thick) which sometimes occur are of the nature of " pseudo-buhrstone " 

 and are filled with bivalves, the only exception noted being Tarritella 

 rnortoni (large). This member disappears below the surface at the mouth 

 of the first large creek flowing from the Georgia side below Fort Gaines_ 75 



50 — Light yellow and gray sandy clays, containing in the sandier portion bowl- 

 ders much like those seen at Bell's landing; no fossils seen. These are 

 undoubtedly the Lower Peach Tree clays and sands. They become more 

 sandy on ascending 170 



51 — Light greenish-yellow sand filled with bits of decomposed shells and large 

 specimens of Ostrcea compressirostra and Venerecardia planicosta. (Inter- 

 val of 50 yards.) 3 



52 — Gray sand filled with decomposed fossils. An irregular indurated ledge 

 (non-fossiliferous) occurs in this stratum. This is probably Bashi, 

 though the only fossil that could be determined with any degree of accu- 

 racy is the small oyster so common at the typical locality 18 



53 — Blue, slightly sandy clay 6 



54 — Light yellow, silicious (sandy) limestone filled with casts and containing 



pockets filled with shells of Ostrcea compressirostra 18 



55 — Gray lignitic sandy clay (Hatchetigbee) 10 



56 — Coarse white sand, containing Ostrcea divaricata and a few other friable 

 shells in the upper part. (The first flexures since leaving Eufaula 



occur in this stratum.) 12 



57 — Plain buhrstone, rather sandy , 40 



68 — Light yellowish-green sand containing numbers of small shells of Ostrcea 



selloefortnis 45 



LXXXVIII— Bull. Geol. Soc. Am., Vol. 2, 1890. 



