abstracts: geology 663 



The section on geologic history describes the interesting succession of 

 events that resulted in the formation of the alluvial lowlands compos- 

 ing the greater part of the area treated. The chapter of the chemistry 

 of the waters contains in addition to the discussion of the character 

 of the Arkansas ground waters, much general information on the min- 

 eral constituents of water, the character of water suitable for boiler 

 use, irrigation, and domestic use, and methods of purifying water. 



L. W. S. 



GEOLOGY. — The Pliocene Citronelle formation of the Gulf coastal plain 

 and its flora. George Charlton Matson and Edward Wilber 

 Berry. U. S. Geological Survey Professional Paper 98-L. Pp. 

 167-208, with 16 plates and 3 figures. 1916. 

 This report describes the character and areal distribution of the 

 Pliocene deposits, chiefly non-marine, occurring near the seaward mar- 

 gin of the Gulf coastal plain from Florida to eastern Texas. These 

 are called the Citronelle formation, which is made to include portions 

 of the deposits formerly classified as "drift," "Orange sand," "Lafay- 

 ette," and "Grand Gulf." The fossil plants, by means of which the 

 age determinations are made, are represented by 18 species. Three of 

 these are Pleistocene and Recent forms and 15 are extinct, the latter 

 embracing 2 West Indian and one non- American type. The plants 

 are, without exception, coastal forms and they indicate climatic condi- 

 tions very similar to those prevailing at the present time along the Gulf 

 coast, and a physiography of barrier beaches and coastal lagoons, with 

 gum swamps and cypress ponds near the coast. It is concluded that 

 this flora flourished in the latter half of the Pliocene. E. W. B. 



GEOLOGY. — The Lower Eocene floras of southeastern North America. 

 Edward Wilber Berry. U. S. Geological Survey Professional 

 Paper 91. Pp. 481, with 117 plates and 16 figures. 1916. 



This report describes a small flora of early Eocene age from Texas, 

 tentatively referred to the Midway formation, and gives an exhaustive 

 discussion of the large flora of the Wilcox Group. The character, 

 succession, areal distribution, and stratigraphic relations of the Wilcox 

 deposits are described, and it is shown that the Wilcox is separated by 

 a hitherto unrecognized time interval from the underlying basal 

 Eocene, or Midway, and from the overlying middle Eocene, or Clai- 

 borne. 



The Wilcox flora, which comprises over 300 species, is fully described 

 and figured, and its composition, distribution, relations, and environ- 



* * • 



\ 





t» 



