244 GEOLOGY. 



haps the Ashley River marl) formerly regarded as late Eocene 

 are now classed as Oligocene. The Ashley River marls of North and 

 South Carolina contain nodular phosphate of lime, locally in such quan- 

 tities as to be eommerically valuable. 1 The Chattahoochee and Chipola 

 beds of Florida are regarded as late Oligocene, 2 and their fossils indicate 

 a climate warmer than that of the Miocene (Upper Miocene of the older 

 classification). Oligocene has been suspected on the Atlantic coast as 

 far north as New Jersey. 3 



The principal formations of the Gulf region which have been corre- 

 lated with the Oligocene of Europe are the Vicksburg (below) and 

 Grand Gulf formations 4 of Alabama, Mississippi, and Louisiana, and 

 the Fayette 5 formation of Texas. The Vicksburg formation (Lower 

 Oligocene) is chiefly limestone, and is closely associated with the Eocene 

 (Jackson) limestone of the same region (p. 199). The Grand Gulf and 

 Fayette formations are made up of sediments which seem to have been 

 brought to the Gulf by the drainage of the present Mississippi basin, 

 and by that of the lesser basins bordering it on either hand. The land- 

 ward parts of these formations are non-marine, while the seaward parts 

 may be marine. The presence of gypsum in the Grand Gulf series 

 gives some suggestions of local conditions, and perhaps of climate. In 

 contrast with most other clastic formations of similar age along the 

 Atlantic seaboard, the Grand Gulf series contains firm sandstone, some 

 of which is even quart zitic. 6 



The Oligocene, especially the early Oligocene, is represented some- 

 what generously about the Caribbean Sea, where its association with 

 the Eocene is generally close, 7 and its separation from the Miocene dis- 

 tinct. This is in keeping with the phenomena of the Gulf States. Lime- 

 stone is the dominant type of rock in the Antillean region. 



1 Penrose Bull., 46, U. S. Geol. Surv. 



2 Dall, op. cit. 



3 Dall, Md. Geol. Surv., Miocene, p. cxli. 



4 Smith, Geol. Surv. of Ala., 1894. See also Dall, 18th Ann. Rept. U.S. Geol. 

 Surv., and Maury, A Comparison of the Oligocene of Western Europe and Southern 

 United States, Bull. Am. Pal., No. 15, p. 43. 



5 Penrose, Geol. Surv. of Texas, 1st Ann. Rept. 



6 The classification of the Grand Gulf formation is in dispute. Some of the beds 

 described under this name are probably younger than Oligocene, See Smith and 

 Aldrich, Science, New Series, Vol. 16, p. 836, and Vol. 18, p. 26. 



7 Hill, Geology and Physical Geography of Jamaica, and Geological History of 

 the Isthmus of Panama and portions of Costa Rica. Bull. Mus. Comp. Zool., Vols. 

 XXVIII and XXXIV respectively. 



