222 ECONOMIC GEOLOGY 
The springs are in granite, which would not provide their 
sodium sulphate, sodium carbonate, and sodium chloride, 
while the waters have also traces of lithium, arsenic, anti- 
mony, tin, and rubidium. The water brings up 2,000,000 1b. 
of sodium sulphate and carbonate a year, while the deposit 
of carbonate of lime chokes the channels, and causes explosions 
unless the outlets are re-bored. The springs vary in tempera- 
ture from 164° F. at Sprudelkessel, said to be the hottest 
spring in Europe, to 118° at Schloss Brunnen ; all the springs 
yield the same constituents and in the same proportions. 
The water obviously comes from a deep-seated source below 
the granite. 
The quantity of plutonic water is incalculable; but the 
amount discharged by volcanic eruptions and hot springs is 
enormous, and as geological time is. estimated in thousands 
of millions of years the contributions must represent an 
important addition to the surface waters. The Carlsbad 
springs discharge 2,000,000 gallons a day, which in 1500 
million years, would have raised sea-level about 160 feet. 
The life of any single hot spring is probably short geologically ; 
but as one channel is closed another is opened elsewhere, 
The oceans must have been much increased by the unceasing 
discharge of plutonic water. Part of the flow from hot 
springs is meteoric water. The water of the hot springs and 
geysers of the Yellowstone Park in the Rocky Mountains 
has been claimed as surface water that has been expelled 
after working its way 8000 feet deep. Half the discharge 
from the springs of Iceland and California has also been 
considered to be meteoric. The efforts to explain the heat 
of these waters by chemical and radioactive processes are 
generally dismissed as unsuccessful. An American sympo- 
sium on hot springs (Fourn. Geol. XxXxii, 1924) concluded 
that the heat must be plutonic although-part of the water 
may be meteoric. As the heat is plutonic probably much 
of the water is so also (cf. A. L. Day and E. S. Shepherd, 
Bull. G. Soc. Amer., xxiv, 1913, p. 606). 
DisposaL oF RaiNraLL—Rain-water is removed from the 
land in three ways—run-off to the sea, return to the air by 
evaporation, and percolation underground. 
* Run-oFrF "—The *“ run-off " is determined by measuring 
the discharge of all the rivers. The percentage varies from