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MINERALOGY. 395 



to raise up the surrounding superposed strata, force its 

 way by a partial explosion, and now the vast quantity of 

 liquid matter overflowing and oscillating from side to 

 side, could emboss it with those igneous masses, which, 

 on cooling, became rocks. The following may also be 

 imagined : A body revolving swiftly on an axis, becomes 

 hotter and hotter, according to the rapidity with which 

 it is turned ; but let the velocity be checked suddenly a 

 cooling process at once begins. This was also the case 

 with our earth in the earliest antediluvian period ; the 

 incandescence or liquifaction gradually cooled down, and 

 continuing after the upheaval, which caused the primary 

 rock formation, the great ice period ensued, and is sup- 

 posed to have continued for many centuries, the remains 

 of which are still occasionally met with. 



It may be imagined that at the time of the ice period 

 the greater portion of the earth's surface was covered 

 with ice. Gradually, however, the imprisoned waters 

 melted, and accomplished great and remarkable changes 

 on the face of the earth. In the large masses of water 

 which now covered the surface of the earth, many whirl- 

 pools and torrents of fearful power were produced, which, 

 tearing away and removing all parts fractured by the 

 upheaval, forced their passage through all obstructions, 

 and formed the valleys, ridges, and other configurations, 

 of which there is palpable evidence at the present day. 

 For instance, on the opposite slopes of great ravines, 

 which those fiercely running waters have excavated in their 

 headlong course, the same course of stratification is ob- 

 served to exist unaltered, except where some volcanic 

 eruption has come in the way, and disturbed the general 

 law. In the low-lying regions of the earth, where the 

 depression of the surface is greatest, as Middle Asia, the 



