Ve cS ee oe ee ae es ee Pee” “*% oo / oT a a eee 
SY ¥ 
236 DYNAMICAL GEOLOGY. 
the most remarkable gas springs in the world. It is a deep, bosky 
hollow, from one small space on the bottom of which carbon dioxide — 

“4 
an 
a . 
issues so copiously as to form the lower stratum of the atmosphere. — 
Tigers, deer, and wild-boar, enticed by the shelter of the spot, descend 
and are speedily suffocated. Many of their skeletons, together with 2 
those of man himself, have been observed. 
As a distinct class of gas-springs we may group and describe here ~ 
the emanations of volatile hydrocarbons, which, when they take fire, 
are known as Fire-wells. These are not of volcanic origin, but arise 
from changes within the solid rocks underneath. They occur in | 
many of the districts where mud-volcanoes appear, as in northern 
Italy, on the Caspian, in Mesopotamia, in southern Kurdistan, and 
in many parts of the United States. It has been observed that they 
frequently rise in regions where beds of rock-salt lie underneath, and 
as that rock has been ascertained often to contain compressed 
gaseous hydrocarbons, the solution of the rock by subterranean 
water, and the consequent liberation of the gas, has been offered as 
an explanation of these fire-wells. 
In the oil regions of Pennsylvania certain sandy strata occur at 
various geological horizons whence large quantities of petroleum and | 
gas are obtained. In making the borings for oil-wells, reservoirs of 
gas as well as subterranean courses or springs of water are met with. 
When the supply of oil is limited but that of gas is large, a contest — 
for possession of the bore-hole sometimes takes place between the 
gas and water. When the machinery is removed and the boring 
is abandoned, the contest is allowed to proceed unimpeded and 
results in the intermittent discharge of columns of water and gas — 
to heights of 130 feet or more. At night, when the gas has been — 
lighted, the spectacle of one of these “ fire-geysers” is inconceivably : 
grand." 
Geysers.—In some regions where volcanic action still continues, 
and in others where it has long been dormant, there occur eruptive 
fountains of hot water and steam, to which the general name of 
Geysers (7.e. gushers) is given, from the examples in Iceland, which 
were the first to be seen and described. The Great and Little 
Geysers, the Strokkr, and other minor springs of hot water in 
Iceland, have long been celebrated. More recently another series 
has been discovered in New Zealand. But probably the most 
remarkable and numerous assemblage is that which within the last 
decade has been brought to light in the north-west part of the 
territory of Wyoming, and which has been included within the 
“ Yellowstone National Park ”—a region set apart by the Congress of 
the United States to be for ever exempt from settlement, and to be 
retained for the instruction of the people. In this singular region 
* Ashburner, Proc. Amer. Phil. Soc., xvii. (1877), p. 127. Stowell’s Petroleum Re- 
porter, loth Sept. 1879. Second Geol. Survey of Pennsylvania. Reports by J. Carll, 
1877, 1880. On the naphtha districts of the Caspian Sea, Abich, Jahrb. Geol. Reichs. 
xxix. (1879), p. 169 ; see also for phenomena in Gallicia the same work, xv. pp. 199, 351; 
xvii. p. 291; xviii. p. 311. 
