36 FLORIDA GEOLOGICAL SURVEY-SEVENTH ANNUAL REPORT. 
Height above river 
(stage of Mar. 5, 1909). 
While the dividing line between the Chattahoochee limestone and 
the Alum Bluff formation is not well marked, it is probable that 
in this section about 90 feet of the Alum Bluff formation is exposed 
including Nos. 2 to 10 of the section. 
Section at Alum Bluff, Liberty County. 
The following section was made'at Alum Bluff a short distance north of the 
middle of the bluff at a point where a recent landslide (reported to have oc¬ 
curred in 1905 or 1906) has left the bluff bare of vegetation. The measurements 
of this section were made by hand level. 
Thickness 
of stratum. 
8. Pale yellow incoherent sand- 30 
7. Reddish and purple sands and sandy 
clays partly covered toward the base 70 
6. Covered- 6 
5. Dark colored sandy non-fossiliferous 
clays, in places tasting of alum- 17 
4. Dark or gray marls, highly fossiliferous 14 
Unconformity. 
3. Laminated and cross bedded sands and 
clays, and blue sands; in places 
absent - 3 
Apparent unconformity. 
2. Light gray calcareous sands or sand^ 
stone - 16 
1. Sands, slightly indurated and weathering 
yellow upon exposure--- 10 
The light gray sandstone (No. 2) of this section is apparently the same as 
No. 4 of the Rock Bluff section, the stratum having been recognized at several 
intermediate localities along the river bluff between the two localities and on 
tributaries entering the river. Samples from this stratum gave the following 
analyses. No. 1 is from Rock Bluff (No. 4 of the section). No. 2 is from Alum 
Bluff (No. 2 of the section). No. 3 from an exposure on a tributary to Sweet 
Water Creek Sec. 5, T. 1 N., R. 7 W. All samples were collected by the writer. 
Analyses made for the State Survey in the office of the State Chemist, B. H. 
Bridges, Analyst. 
feet 
136 
to 
166 
feet. 
feet 
66 
to 
136 
feet. 
feet 
60 
to 
66 
feet. 
feet 
43 
to 
60 
feet. 
feet 
29 
to 
43 
feet. 
feet 
26 
to 
29 
feet. 
feet 
10 
to 
26 
feet. 
feet 
0 
to 
10 
feet. 
No. 1. 
No. 2. 
No. 3. 
Silica (Si 0 2 ) -- 
- 48.44 
53-02 
34-03 
Calcium carbonate (CaCCh) 1 — 
- 38.57 
38.57 
35-35 
Magnesium carbonate (MgCCX) 1 
1.68 
1.84 
26.00 
Iron and Alumina (Fe 2 0 3 and AL 
2O3) 
_ 2.88 
3.96 
3.20 
Phosphoric acid (P 2 0 5 ) - - 
Trace 
0.22 
Trace 
Sulphate (SCh) - 
- Trace 
Trace 
Trace 
Moisture (100 degrees F.) - 
,-- 1.37 
1.60 
1.32 
Calculated from the oxides. 
0.80. No. 2, Calcium oxide, 21.60; 
No. 1, Calcium oxide, 21.60; magnesium oxide, 
magnesium oxide, 0.88. No. 3, Calcium oxide, 
19.80; magnesium oxide, 12.39. 
