50 
FLORIDA GEOLOGICAL SURVEY—THIRD ANNUAL REPORT. 
had a part. The land surface when first elevated above sea was 
evidently much more nearly level than at present. Upon being- 
lifted above sea level irregularities in topography rapidly develop. 
A first step in the process of erosion is the development of 
stream channels and valleys, largely through mechanical erosion. In 
addition to mechanical erosion, crusion by solution due to under¬ 
ground water is likewise in process especially in sections underlaid 
by limestones. 
As illustrating the efficiency of underground water as an erod¬ 
ing agent, the writer in a previous report computed the rate of 
erosion by solution in the sections of the state underlaid by lime¬ 
stones.* The estimate of the rate of solution given below is taken 
from that report. 
Solution is the most apparent, and geologically the most im¬ 
portant result of underground water circulation. Rain water, while 
passing through the air, takes into solution a small amount of 
CO2 gas. To this is added organic and mineral acids taken up 
while passing through the soil. Increased pressure, as the water 
descends into the earth, enables the water to hold in solution greater 
quantities of gases, acids and salts, all of which greatly increase the 
dissolving power of the water. 
That underground water is efficient as a solvent is evident from 
the analyses of well and spring waters. Rain water entering the 
earth with almost no solids in solution, returns to the surface 
through springs and wells with a load of mineral solids in solution 
determined by the length of time it has be^n in the ground, the 
distance traveled, and the character of the rocks and minerals with 
which it comes in contact. 
The mineral matter thus taken into solution is carried along 
with water, and, while some of it is re-deposited, a large amount is 
removed annually. 
An estimate of: the total mineral solids thus removed is difficult. 
A conception of the largeness of the amount removed is obtained 
from a consideration of some of the individual springs. 
The water of Silver Springs contains, as shown by analysis, 274 
parts solids per million parts water. Otherwise expressed, each 
million pounds of water is carrying with it 274 pounds of solids in 
solution. Silver Spring is estimated to flow a little more than 
three million pounds of water per minute (368,913 gallons). The 
interior of Florida is thus being carried into the ocean through Sil¬ 
ver Springs at the rate of more than 340 pounds per minute, or 
about six hundred tons per day. 
*Fla. Geol. Survey Bulletin No. 1, pp. 46, 47, 48, 1908 
