162 FLORIDA GEOLOGICAL SURVEY—FOURTH; ANNUAL REPORT. 
The production of phosphate rock in Florida during 1911 was 
again in excess of that of any preceding year. The production for 
1910 was approximately 2,029,797 long tons, while the output for 
1911 was 2,494,572 long tons, an increase of nearly a half million 
tons. The increase occurred in both the hard rock and the pebble 
fields, although the percentage of increase was greatest in the pebble 
field. 
The amount of phosphate rock consigned for use in the United 
States showed a further decided increase. The total domestic ship¬ 
ments of phosphate rock during 1910 from Florida was 1,014,473 
tons, while during 1911 the domestic shipments amounted to 
1,290,779 tons, from which it appears that slightly more than one 
half of the phosphate produced in Florida is consigned to points 
within the United States. 
HARD ROCK PHOSPHx\TE. 
The year 1911 witnessed renewed activity in the mining of hard 
rock phosphate in Florida, with the result that the output was ap¬ 
preciably increased over that of the preceding year. The total 
output of hard rock phosphate in Florida for the year 1910 was 
392,088 long tons. The amount mined during 1911 was 474,094 
tons. Although showing this increase, the production in 1911 does 
not equal that of 1909, which was 527,582 long tons, nor that of the 
record year 1908, which was 768,011 long tons. 
The total number of plants operating.in the hard rock section 
at the beginning of 1911 was forty-five. A number of these worked 
out deposits, or for other reasons closed down, while several new 
plants were built. The number of plants operating at the close of 
the year was forty-three. Fourteen companies operated in the hard 
rock section during 1911. 
A notable feature in the development of the hard rock industry 
was the construction of a dam across the Withlacoochee River, as 
a result of which it has been possible to supply electric power to a 
number of the phosphate plants in Citrus and Marion Counties. 
With the aid of electric power and light some of the mines have 
been able to work day and night shifts, thereby materially increas¬ 
ing the output. The practice of removing overburden by hydraulics 
has also been extended during the year in the hard rock section, 
and has further facilitated the production of rock. 
The domestic shipment of hard rock during 1911 was 16,723 
tons, as against 18,745 tons during the preceding year. The amount 
