186 GEOLOGY. 



and much higher in the profounder depths ; and farther, 

 that the half-molten crust of the earth, stretched out over 

 a molten abyss, was so thin that it could not support, 

 save for a short time, after some convulsion, even a small 

 island above the sea level. What, in such circumstances, 

 would be the aspect of the scene, optically exhibited 

 from some point in space elevated a few hundred yards 

 over the sea ? It would be simply a blank, in which the 

 intensest glow of fire would fail to be seen at a few yards' 

 distance. An inconsiderable escape of steam from the 

 safety-valve of a railway engine forms so thick a screen 

 that, as it lingers for a moment, in the passing, opposite 

 the carriage windows, the passengers fail to discern 

 through it the landscape beyond. A continuous stra- 

 tum of steam, then, that attained to the height of even 

 our present atmosphere, would wrap up the earth in a 

 darkness gross and palpable as that of Egypt of old a 

 darkness through which even a single ray of light would 

 fail to penetrate. And beneath this thick canopy the 

 unseen deep would literally " boil as a pot" wildly tem- 

 pested below; while from time to time, more deeply 

 seated, would upheave suddenly to the surface vast 

 tracts of semi-molten rock, soon again to disappear, and 

 from which waves of bulk enormous would roll outward, 

 to meet in wild conflict with the giant waves of other 

 convulsions, or to return to hiss and sputter against the 

 intensely-heated and fast-foundering mass, whose violent 

 upheaval had first elevated and sent them abroad." At 

 length, however, the earth's forming crust would cool 

 down, so that the steam atmosphere would become less 

 thick, and after a time the rays of the sun would strug- 

 gle through, forming at first a faint twilight, but gradu- 

 ally strengthening as the age advanced. At its close, 

 " day and night the one still dim and gray, the other 

 wrapped in a pall of thickest darkness would succeed 

 each other as now, as the earth revolved on its axis, and 

 the unseen luminary rose high over the cloud in the east, 



