212 
FLORIDA statl geological survey. 
Stratigraphic Position:—The relations of the Miami oolite to the 
other limestones described in this paper are not definitely established. 
The extent of the oolite north, west, and southwest is obscured by 
sand or swamp deposits. The rock is perhaps younger than the Palm 
Beach limestone and is younger than the lower part of the Key Largo 
limestone. It lies almost flat. 
While the Miami oolite is so overlain by unconsolidated deposits 
that its field relations can not be determined with exactness, well re¬ 
cords and samples from a few wells show what is below it at several 
places. At Miami samples from the wells of the water company show 
that the oolite loses its typical appearance a few feet below sea level 
and rests on an irregularly cemented aggregate of shell fragments and 
quartz sand. At Dania the oolite rests on “blue mud,” at Port Lauder¬ 
dale on “sand.” 
Lithologic Characteristics:—Typically the rock is a soft white 
oolitic limestone, containing streaks or thin irregular layers of calcite 
separating less crystalline streaks. The rock breaks with an irregular 
fracture, dresses nicely, hardens on exposure and makes good road 
metal and building stone. 
Hand specimens show that the oolite carries a varying proportion 
of quartz sand. The grains are mostly small and angular to sub- 
angular in outline; occasionally there is a large, rounded grain. On 
the average the grains are considerably smaller than the ovules, which 
have a mean longest diameter of pj to L* mm - 
The proportion of quartz sand is greatest to the north. Along the 
drainage canal west of Port Lauderdale there are found in the oolite 
streaks of sand so loosely cemented that perfectly preserved shells of 
Chione cancellated can be picked out with the fingers, while at Long 
Siding quartz grains in the oolite are relatively rare. Besides being 
more plentiful to the north, the sand grains seem to form a larger 
proportion of the rock near Biscayne Bay than farther west, as on 
Long Key. 
Examination with the microscope shows that the ovules have a well 
marked concentric structure; the nucleus of some ovules is a rounded 
aggregate of minute calcite crystals, of others a rounded aggregate 
less-evidently crystalline; sometimes the nucleus is a shell fragment 
and frequently it is a grain of quartz. The concentric layers vary in 
number from one to four or five, and in appearance from dear and 
rather coarsely crystalline to opaque, the layers are darker or lighter 
from varying amounts of organic matter and amorphous material. 
Thickness:—A well at Port Lauderdale, according to the driller, 
went through twelve feet of oolitic limestone, one at Dania forty feet 
of oolite, and the wells of the Miami Water Company found about 
