PART 'II. CHAPTER XII. 



155 



Neptunian Theory of the Origin of Granite. 



under such circumstances the name of transition was retained, it 

 is clear that it ought to have been appHed without reference to 

 the age of strata, and simply as expressive of a mineral pecu- 

 liarity. The continued appropriation of the term to formations 

 of a given date, induced geologists to go on believing that the 

 ancient strata so designated bore a less resemblance to the se- 

 condary than is really the case, and to imagine that these last 

 never pass, as they frequently do, into metamorphic rocks. 



The poet Waller, when lamenting over the antiquated style of 

 Chaucer, complains that — 



We write in sand, our language grows, 

 And, like the tide, our work o'erflows ; 



But the reverse is true in geology ; for here it is our work 

 which continually outgrows the language. The tide of observation 

 advances with such speed, that improvements in theory outrun 

 the changes of nomenclature ; and the attempt to inculcate new 

 truths by words invented to express a different or opposite opin- 

 ion, tends constantly, by the force of association, to perpetuate 

 error ; so that dogmas renounced by the reason still retain a 

 strong hold upon the imagination. 



In order to reconcile the old chronological views with the new 

 doctrine of the igneous origin of granite, the following hypothe- 

 sis was substituted for that of the Neptimists. Instead of begin- 

 ning with an aqueous menstruum or chaotic fluid, the materials 

 of the present crust of the earth were supposed to have been at 

 first in a state of igneous fusion, until part of the heat having 

 been diffused into surrounding space, the surface of the fluid con- 

 solidated, and formed a crust of granite. This covering of crys- 

 talline stone, which afterwards grew thicker and thicker as it 

 cooled, was so hot, at first, that no water could exist upon it; but 

 as the refrigeration proceeded, the aqueous vapour in the atmo- 

 sphere was condensed, and, falling in rain, gave rise to the first 

 thermal ocean. So high was the temperature of this boiling sea, 

 that no aquatic beings could inhabit its waters, and its deposits 

 were not only devoid of fossils, but, like those of some hot springs, 

 were highly crystalline. Hence the origin of the primary or 

 crystalline strata. 



Afterwards, when the granitic crust had been partially broken 

 up, land and mountains began to rise above the waters, and rains 

 and torrents ground dov/n rock, so that sediment was spread over 

 the bottom of the seas. Yet the heat still remaining in the solid 

 supporting substances was sufficient to increase the chemical 

 action exerted by the water, although not so intense as to pre- 

 vent the introduction and increase of some living beings. During 



