92 FLORIDA GEOLOGICAL SURVEY ELEVENTH ANNUAL REPORT. 
4. Sloping and covered with sand and pebble 25 ft. 
3. Limestone ledge, fossils mostly as casts 3 ft. 
2. Yellow and blue clays, leaf impressions 2 ft. 
1. Marl with many fossils mostly preserved as casts, silicified oysters 
abundant near the top 6 ft. 
Numbers 1 to 3 of this section represent the Alum Bluff forma- 
tion. From the. leaf impressions Mr. E. W. Berry identified the 
species Fagara apalachicolensis and Sabalites apalachicolensis , both 
of which had previously been obtained from 1 the Alum Bluff forma- 
tion at Alum Bluff. (Letter of March 21, 1916). The inverte- 
brate fossils obtained at this locality are being utilized by Dr. 
Gardner in her study of the faunas of the Alum Bluff formation. 
At Red Head Still on the east bank of the Choctawhatchee River 
25 miles from the Gulf, is an exposure of oyster shell marl and 
clay, about five feet being seen above low water. The fossils from 
this locality include chiefly a very large oyster which Miss Gardner 
has identified as Ostrea hait ensis, a species common in the West 
Indies and in the Alum Bluff formation.* This exposure is a few 
miles above the post office Ebro, but below the entrance of Holmes 
Creek. 
STRUCTURE. 
The position of the belt of outcrops of the Alum Bluff forma- 
tion indicates that the strike of the formation in this area is from 
slightly north of west to south of east. The dip to the south or 
slightly west of south although moderate is in excess of the gradient 
of the streams. On the Choctawhatchee River, as has been stated, 
the shell marl phase of the formation remains above water level to 
within a few miles of tidewater. It is probable that on Choctaw- 
hatchee Bay this formation will be found scarcely above tide- 
water. On the Apalachicola River the formation, as previously 
noted probably lies above water level as far south as Estiffanulga 
which is slightly south of east of its last observed exposure on the 
Choctawhatchee River. On the Chipola River the formation is 
known to pass below water level a few miles below Clarksville, 
the Choctawhatchee formation being at water level at Darling 
Slide and at Abes Spring. Since these two formations are tin- 
conformable it is difficult to determine whether the sections of the 
* Letter of January 25, 1916. 
