200 EARTHQUAKES. 
‘“By the earthquake of 1839 the island of Lemus was 
suddenly elevated eight feet.’? And, during the earth- 
quakes of Concepcion, in 1835, the coast was lifted sev- 
eral feet above the sea-level. While, by the Owen’s 
valley earthquake, in 1872, a fault was produced. forty 
miles long and from five to twenty-five feet in height. 
Wherever rock-fractures and displacements have 
taken place, there can be no doubt but they have re- 
sulted from the action of seismic forces. 
Humboldt saw in ‘‘the reaction of the fiery interior 
of the earth upon its rigid crust’’ a cause sufficient to 
explain seismic and volcanic phenomena. Some have 
suggested that this ‘‘reaction’’ consists in the sudden 
outbursts of steam beneath the earth’s crust, and its 
escape through cracks and fissures. 
Whether steam accumulates by ‘‘ separating out from 
the cooling interior of our globe” or resuits from the 
‘“ percolation of water from the surface of the earth down 
to voleanic foci,’ there can be no doubt but its expansive 
force is capable of causing a sudden explosion, and 
thereby be averitable cause of seismic phenomena.  Fis- 
sures beneath the ocean—where the most destructive 
earthquakes have arisen—may ‘‘ admit water to volcanic 
foci ;’ the intense heat to which it is submitted will, for 
a time, hold a portion of the water in a spheroidal state, 
during which time tremors may be felt, and then when, 
from the spheroidal state the water is converted into 
steam, its expansive force causes explosions which are 
felt as earthquakes. 
Again it is said that the evisceration which takes place 
on such an immense scale during volcanic action—when 
lava is ejected in such quantity that in some individual 
cases it has exceeded the magnitude of Mount Blane ;. 
or ona smaller scale by the mining excavations in our 
coal fields, and mineral mines, and from the outpouring 
of petroleum oil, and gas, whereby subterranean hollows 
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