50 FLORIDA GEOLOGICAL SURVEY TENTH ANNUAL REPORT. 
FORMATION NAME. 
The differentiation of the superficial formations has proven 
one of the most difficult problems in coastal plains geology. That 
this is true is evident from the number of formation names that 
have been proposed and abandoned or subsequently restricted, as 
well as by the voluminous discussion that this subject has given rise 
to. The Lafayette formation was formerly believed to be very 
extensively developed in the coastal plains. In recent years, how- 
ever, it has been maintained by a number of geologists that super- 
ficial materials from several different formations have been included 
under this term. In 1884 Loughridge described materials in Georgia 
to which Dali in 1892 applied the term Altamaha Grit. These ma- 
terials were more fully described under the term Altamaha for- 
mation by Veatch in 1908* and by Stephenson and Veatch in 
1911.4 At this time Stephenson and Veatch recognized that the 
materials referred to this formation, extending over about 21,000 
square miles of Georgia from the Savannah river to the Florida 
State line, possibly contained parts of various formations. Subse- 
quently, these writers expressed the conclusion that the. greater 
part of the materials referred to the Altamaha grits belonged to 
the Alum Bluff formation or to other Cretaceous and Tertiary 
formations . % In 1916 Matson and Berry described the Citronelle 
formation, the tpye locality of which is in Alabama. § This for- 
mation which is of Pliocene age, is regarded as extending into the 
western part of Florida. Matson has suggested that possibly the 
red sands in the section at Alum Bluff represent this formation. 
The red and mottled sands and sandy clays of this area are in 
places similar to those that have been referred to the Lafayette for- 
mation, elsewhere it resembles that which formerly was placed in 
the Altamaha formation of Georgia. If Altamaha is retained as 
a formation name, restricted if necessary to the deposits consisting 
chiefly of red sands and clays lying above the Miocene, it is very pos- 
* Science, n. s. Vol. 27, Jan., 1908, pp. 71-74. 
tGeol. Surv. Ga. Rpt. 26, pp. 400-423, 1911. 
tU. S. G. S. Water Supply Paper, 341, p. 94, 1915. 
§The Pliocene Citronelle formation of the Gulf Coastal Plain ; U. S. Geol. 
Survey, Prof. Paper 98, pp. 167-192, 12 pis., 3 fig., September 11, 1916. Ab- 
stract, Washington Acad. Sci., Journ., Vol. 6, No. 19, p. 663, November 19, 1916. 
