Mabch 30, 1906.] 



SCIENCE. 



483 



vestigations were mainly confined. 



Little or nothing was done in continua- 

 tion of these observations until 1887, when 

 Daniel W. Langdon, of the Alabama Geo- 

 logical Survey, discovered on the Chatta- 

 hoochee River a series of marine Tertiary 

 beds of Miocene age directly overlying the 

 Vicksburg limestone, which, before that 

 time, had been considered the uppermost 

 of the marine Tertiary formations of the 

 Gulf coast.^ By this capital discovery in- 

 terest in the later Tertiary formations of 

 this region, especially in Florida, was 

 greatly stimulated, in part because of the 

 great number and beautiful state of pres- 

 ervation of the fossil shells, and the geolo- 

 gists, paleontologists and shell collectors of 

 the U. S. Geological Survey were soon 

 abroad in the land, with the result that 

 other occurrences of Miocene strata were 

 speedily made known, especially east of the 

 Chattahoochee River, at Coe's Mill and 

 other localities down the western side of 

 the peninsula where the exposures are more 

 numerous and continuous. 



West of the Chattahoochee also, on 

 Chipola River not far from Alum BlufE, 

 on Shoal River in Walton County, and 

 even as far westward as Oak Grove on 

 Yellow River in Santa Rosa County a few 

 miles below the Alabama line, beds with 

 Miocene shells in an almost perfect state of 

 preservation were quickly added to the list 

 of desirable collecting grounds. 



North of Oak Grove and on the banks 

 of the Conecuh River near Roberts in 

 Escambia County, Alabama, some poorly 

 preserved but still identifiable shell casts 

 of Miocene forms were found by Mr. L. C. 

 Johnson, of the Alabama Geological Sur- 

 vey, in beds which were very close above 

 the Vicksburg limestone and consequently 

 near the horizon of the lower Chattahoo- 

 chee. The westernmost occurrence of the 



• Report on the Coastal Plain of Alabama, Mont- 

 gomery, Alabama, 1894. 



post-Eocene marine Tertiaries was also dis- 

 covered by Mr. Johnson near Merrill in 

 Greene County, Mississippi, at the conflu- 

 ence of Leaf and Chickasawhay rivers, 

 which make the Pascagoula. Here in the 

 banks of Chickasawhay is a bed made up 

 almost exclusively of the shells of a small 

 gnathodon or rangia, along with some large 

 but very badly preserved oysters (0. Vir- 



Inasmuch as this was in territory 

 mapped by Hilgard as Grand Gulf, and as 

 the strata of the latter formation, contain- 

 ing lignitized and silicified trunks of trees, 

 formed the upper two thirds of the bluff 

 at the place, the gnathodon bed was con- 

 sidered as a part of the Grand Gulf, and 

 the name Pascagoula was given to it. Pro- 

 visionally, at least, the horizon was de- 

 termined to be Miocene and equivalent to 

 the uppermost of the Alum Bluff beds, 

 but the subsequent determination by Mr. 

 Dall of the oyster above mentioned, as 0. 

 Virginica, would make the horizon Plio- 

 cene, since 0. Virginica is not known in 

 strata older than the Pliocene. 



It may be here remarked that this shell- 

 bearing bed is not a part of the Grand 

 Gulf, since in a deep well bored in Mobile, 

 Ala., in 1894-5, it was penetrated at the 

 depth of 700 feet, while the Grand Gulf 

 there is at the surface. 



But the Chattahoochee River section still 

 held the first place, as alone showing clearly 

 and unmistakably the order and succession 

 of most of these beds; for, from Chatta- 

 hoochee Landing down to Alum Bluff, as 

 first demonstrated by Langdon and since 

 verified by numerous geologists, there is 

 a practically unbroken series of marine 

 strata exposed along the banks and bluffs 

 of the river. 



At several points, and especially in the 

 upper part of the Chattahoochee series, 

 there are beds with well-preserved shells 

 which have been studied and described 



