SECOND ANNUAL REPORT—STRATIGRAPHIC GEOLOGY. 
141 
probably means that the deposition of the upper part of the gravels 
took place when the land was rising rapidly enough to rejuvenate 
the streams and thus permit them to carry materials from some dis¬ 
tance inland, beyond the belt of rocks which supplied the phosphatic 
pebbles. 
f’ l 
PLIOCENE? 
LAFAYETTE FORMATION. 
The Lafayette formation occupies a "large area in the Coastal Plain 
and has been discussed by a number of authors. The most compre¬ 
hensive report dealing with this formation is that of .McGee 1 , published 
in the Twelfth Annual Report of the United States Geological Survey. 
The name is derived from Lafayette 2 County, Mississippi, where the 
formation is well developed. The name Lafayette formation is synony¬ 
mous with “Orange sand” and “Appomattox formation.” However, 
it is probable that each of these names may, at times, have been used to 
include beds of various geological ages, and hence the exact signifi¬ 
cance of the terms have varied with localities, and even in a single 
locality various writers may have used the names with a different 
significance. 
The Lafayette formation, as the term is used in this discussion, is 
the equivalent of the Lafayette of Smith , 3 and it is doubtless the equiv¬ 
alent of the upper part of the Altamaha grit of Veatch . 4 
Stratigraphic Position:—The Lafayette formation rests unconform- 
ably upon the Alum Bluff and older formations. The amount of time 
represented by the unconformity at the base of this formation is diffi¬ 
cult to determine. The surface upon which the Lafayette was depos¬ 
ited appears to have been comparatively even; but this may either 
mean that it had not been extensively eroded after’ the deposition of 
the older formations; or that it had been worn down to a nearly uni¬ 
form altitude. The Lafayette formation is unconformably overlain 
by the white sand of Pleistocene age, and in this case the extensive 
erosion which occurred between the deposition of the two formations 
indicates the lapse of considerable time during which there were 
marked changes in the altitude and surface configuration of the land. 
1 McGee, W. J., U. S. Geol. Bur:, 12th Ann. Rept., 1890-91, pt. 1, pp. 347-521, 
1892. 
2 Hilgard, E. W., Orange Sand, Lagrange and Appomattox, Am. Geol., vol. 
vii, 1891, pp. 129-131. 
3 Smith, Eugene Allen. The Underground Water Resources of Alabama, 
Geol. Surv. of Alabama, 1907, pp. 24-25. 
4 Veatch, Otto. Altamaha formation of the Coastal Plain of Georgia, 
Science, N. S., vol. xxvii, No. 680, 1908, pp. 71-74. 
