190 Professor Sepewick on the 
difficulty of conceiving any powers in nature capable of producing 
such an effect. But all the phenomena of Geology shew, that the 
great disturbing forces by which the crust of the globe has been 
modified, acted in former times with incomparably more energy 
than they do at present. Volcanic forces are now employed in lifting 
a column of melted lava to the lips of a crater. The same kind 
of forces acting with more energy, and through a wider region, 
may, in the early history of the globe, have been employed in 
lifting islands, and even continents, from the bottom of the ocean. 
During an operation like this, the elastic forces acting from below, 
may often have driven masses of fluid lava among the superin- 
cumbent strata; and, im every case, the lava would naturally be 
propelled through those portions which were most easily pene- 
trated. In such a state of things, a great lateral mjection would 
not only be a possible, but a probable circumstance. For if the 
lava acting on the superincumbent strata, were in a fluid state, 
the lateral pressure must, at every point, have been exactly equal 
to the vertical pressure. The expansive forces may not, at any 
point, have been able to drive a column of lava through all the 
solid unbroken beds; but the lateral forces may have driven a por- 
tion of the fluid between the partings of two horizontal beds, 
and when a penetration of this kind was once effected, the lava 
would act like a wedge at a mechanical advantage, and rush in 
a horizontal stream to a distance proportioned to the elastic forces 
which were in action. 
To break through a mass of solid strata, might require a force 
almost infinite, but te produce a lateral injection between two 
horizontal beds, would only require the lava to be fluid, and 
the expansive force to be greater than a given pressure. It is, 
I think, perfectly clear, that lateral injections must generally take 
place when voleanic forces act upon unbroken stratified rocks. 
If, in such a case, the pressure upwards becomes greater than 
