218 | ANNUAL REPORT SMITHSONIAN INSTITUTION, 1946 
casing are known, it is impossible to determine the composition of the 
water from individual aquifers. 
In spite of these difficulties, enough information is available in some 
regions to indicate definitely that certain formations yield water with 
a high fluorine content, and a number of these formations can be 
shown to have been deposited during periods of volcanic activity. 
INSTANCES OF FLUORINE-RICH AQUIFERS 
In the Gulf Coastal Plain, for example, deposits of pyroclastic ma- 
terial indicate that explosive volcanic activity was widespread and 
recurrent throughout Cretaceous and Tertiary time.® Sufficient in- 
formation is not available to prove that all water-bearing formations 
deposited during these periods of volcanism have a high fluorine 
content, but some of them definitely do. For example, basal Upper 
Cretaceous rocks—the Woodbine sandstone and its equivalents—con- 
tain volcanic materials over a wide area in Texas, Oklahoma, Arkan- 
sas, and Louisiana. In northeastern Texas the Woodbine, which in 
places is lignitic, typically yields water containing more than 1.0 
p. p. m. of fluorine, the recorded range being 0.7 to 6.0 p. p. m.” 
In Alabama and Mississippi the Eutaw formation, a little younger, 
contains volcanic-ash deposits, phosphatic material, and lignite, and 
in Alabama it is the chief source of the fluorine in the water supplies.” 
In Sarasota County, Florida, the Hawthorn formation, Miocene in 
age, contains volcanic material and phosphates and furnishes water 
high in fluorine (1.0-3.4 p. p. m.).” In Louisiana, also, toxic amounts 
of fluorine occur in water from a Miocene sandstone containing tuf- 
faceous material.** For one of the formations in this region yielding 
water notably high in fluorine, no relationship with volcanic activity 
has yet. been found. This is the Trinity formation, of Lower Cre- 
taceous age, an important aquifer in northeastern Texas. The basal 
part of it is lignitic and may therefore contain pyrite. 
In the central and northern Great Plains also, Cretaceous and Ter- 
tiary rocks contain much volcanic material, and lignite and associated 
19or a summary of the literature on this subject see Ross, C. S., Miser, H. D., and 
Stephenson, L. W., Water-laid volcanic rocks of early Upper Cretaceous age in southwestern 
Arkansas, southeastern Oklahoma, and northeastern Texas, U. S. Geol. Surv. Prof. Pap. 
154-F, 1929. 
20 Sundstrom, R. W., Hastings, W. W., and Broadhurst, W. L., Public water supplies in 
eastern Texas, 2 vols., Texas Board of Water Engineers, 1945. 
21 Carlston, C. W., Fluoride in the ground water of the Cretaceous area of Alabama, Geol. 
Surv. Alabama Bull. 52, 1942. 
2 Bay, H. X., The bleaching clays of Florida, in Clay investigations in the southern 
States, 1934-35, by W. B. Lang, P. B. King, et al., U. S. Geol. Surv. Bull. 901, pp. 302-317, 
1940; Stringfield, V. T., Ground water resources of Sarasota County, Fla., 23d—24th Ann. 
Rep. Florida State Geol. Surv., 1930-32, Tallahassee, pp. 121-194, 1933; unpublished 
water analyses of the U. S. Geological Survey. 
23 Maher, J. C., Fluoride in the ground water of Avoyelles and Rapides Parishes, Louisiana, 
Louisiana Geol. Surv. Geol. Pamph. No. 1, 1939. 
