ON GEOLOGY. 73 



pores, and other coral zoophytes of wonderful industry and perseverance, of 

 which the South Sea furnishes us with the largest and most astonishing spe- 

 cimens. These islands are for the most part flat and low, and surrounded by 

 enormous belts of coral reefs. Most of the calcareous zoophytes are em- 

 ployed in their construction, but the principal worm is the madrepora lubricata 

 of Linnaeus. 



In so large an abundance, and with so much facility, is calcareous matter 

 elaborated by these, as well as by various other animals, and especially the 

 testaceous worms, that M. Cuvier is inclined to ascribe all the calcareous 

 rocks that enter into the solid crust of the earth to an animal origin.* But 

 this is to suppose the earth of a far higher antiquity, and to have been the 

 subject of more numerous general deluges, and inversions of sea and land, 

 than are called for by the Wernerian system, or appear reconcileable with the 

 Mosaic narrative. M. Cuvier apprehends, indeed, that such catastrophes may 

 have occurred five or six times in succession, at a distance of four, five, or 

 six thousand years from each other ; and that even the chalk formation found 

 in the basin of Paris originated in a revolution of this kind that occurred an- 

 tecedently to that which is usually regarded as the flood of Noah. And, fol- 

 lowing up this idea, he conceives, towards the close of his Introductory 

 Theory of the Earth, that if the science of fossil organic productions could 

 be carried to a much higher degree of perfection, we should be able to obtain 

 far fuller information upon this subject ; " and man, to whom only a short 

 space of time is allotted upon the earth, would have the glory of restoring the 

 history of thousands of ages which preceded the existence of the human race, and 

 of thousands of animals that never were contemporaneous with his species." 



LECTURE VII. 



ON GEOLOGY. 



(The subject continued.) 



IN our last study I attempted a brief sketch of the chief phenomena that 

 occur to the eye of the geologist upon a survey of the solid crust of the earth, 

 as far as he is able to penetrate into it. The conclusion to which such phe- 

 nomena lead us is the following : that the rudimental materials of the globe, 

 to the utmost depths we are able to trace them, existed at its earliest period, 

 in one confused and liquid mass; that they were afterward separated, and ar- 

 ranged by a progressive series of operations, and a uniform system of laws, 

 the more obvious of which appear to be those of gravity and crystallization ; 

 and that they have since been convulsed and dislocated by some dreadful 

 commotion and inundation that have extended to every region, and again 

 thrown a great part of the organic and inorganic creation into a promiscuous 

 jumble. 



Now, the only two causes that can enter into the mind of man as being 

 competent to the fluidity that apppears at first to have existed throughout the 

 whole crust of the earth are FIRE, or a peculiar SOLVENT. But, if a solvent, 

 that solvent must have been WATER : for there is no other liquid in nature 

 in sufficient abundance to act the part of a solvent upon a scale so extensive. 



And hence our inquiries into this subject become in some degree limited, 

 and are chiefly confined to what have been called the PLUTONIC and the NEP- 

 TUNIAN hypotheses ; the origin of the world in its present state from igneous 

 fusion, and from aqueous solution. Both these theories are of very early 



* Some writers have proceeded much further than this, for they have resolved all the solid materials of 

 the earth's crust i loan organic origin. Such was the opinion of Demaillet and Lamarck, who suppose 

 that every thing was originally fluid ; that this universal fluid gave rise to plants and animals; that all 

 clay or argillaceous earth is the produce of the former ; all calcareous earth of the latter ; and that siliceous 

 earth has been the result of the two. Telliamid, p. 169. Philosophie Zoologique, passim 



