208 FLORIDA GEOLOGICAL SURVEY-SEVENTH ANNUAL REPORT. 
If this is a shell marl, or shells are found in the soil mass, the term 
“shell hammock” is used.* 
In the classification and separation of the soils found in this sur¬ 
vey a number of factors were considered, such as the physical prop¬ 
erties, the source of material and its mode of origin, the topographic 
features and position as to drainage, the characteristic vegetation, 
and the agricultural value. For convenience in classification and 
correlation soils of like properties, derivation, and position as to 
drainage are grouped in soil series. The series are divided into 
types, which differ in the texture of the component particles. Ex¬ 
clusive of Swamp, 17 types of soil were mapped in the Ocala area. 
These fall into six series. 
The surface soils of the area are, with two exceptions, sandy. 
The members of three series consist of sand throughout the soil 
profile to a depth of 36 inches or more. The other three series in¬ 
clude types having clay at or near the surface. The textural range 
of the sandy material is from medium to fine. Such textural varia¬ 
tions are localized. In the western half of the area the texture of 
all the soils is fine, while to the east they are of coarser or medium 
grades. 
The Ocala area, as previously mentioned in this report, is in¬ 
cluded in the limestone region of the State, limestone underlying the 
entire area at varying depths. The limestone is of varying compo¬ 
sition, and consists of consolidated marine sediments belonging to 
the Oligocene of the Tertiary period. 
There are two divisions of the Oligocene—the Vicksburg lime¬ 
stone and on top of this the Apalachicola group of formations, which 
include impure limestones, clays, and sands or sandstones. In this 
area the Apalachicola rocks have practically all been weathered to 
the soil. The Vicksburg is a white, soft, porous limestone, with 
included beds of marl and chert. The soil of the “high hammock” 
land has been affected more or less by material derived from cherty 
beds of limestone. In the low-lying areas flinty outcrops occur. 
Evidently the limestone has had no effect on the deep superficial 
beds of sand. In the western part of the area phosphatic rocks have 
been formed, and these underlie the sand at depths so great that they 
too do not have influence 011 the overlying surface soils. 
*For more complete details of the classification of soils as given in the 
above paragraphs see the Florida State Geological Report, particularly the 3d 
and 4th annual reports. 
