BASALT, AND TRAP. 47 
them the earth affords no stable resting i^lace, 
but during the paroxysms of volcanic activity, 
reels to and fro, and vibrates beneath their 
feet ; overthrowing cities, yawning with dreadful 
chasms, converting seas into dry lands, and dry 
lands into seas. (See LyelFs Geology, vol. i. 
Passim.) 
To the inhabitants of such districts we speak 
a language which they fully comprehend, when 
M^e describe the crust of the globe as floating on 
an internal nucleus of molten elements ; they 
have seen these molten elements burst forth in 
liquid streams of lava ; they have felt the earth 
beneath them quivering and rolling, as if upon 
the billows of a subterranean sea ; they have 
seen mountains raised and valleys depressed ^ 
almost in an instant of time ; they can duly 
appreciate, from sensible experience, the force 
of the terms in which geologists describe the 
tremulous throes, and convulsive agitations of the 
earth ; during the passage of its strata from the 
bottom of the seas, in which they received their 
origin, to the plains and mountains in which they 
find their present place of rest. 
We see that the streams of earthy matter, 
which issue in a state of fusion from active 
volcanoes, are spread around their craters in 
sheets of many kinds of lava ; some of these so 
much resemble beds of basalt, and various trap 
rocks, that occur in districts remote from any 
