GEOLOGY. 



lity, has been nearly adopted in modern 

 times, by Gensanne, in his "History of Lan- 

 guedoc;" who imagines the existence of a 

 central fire, by the influence of which nu- 

 merous mineral principles are raised, in a 

 state of vapour, through the different clefts 

 of the earth, until they arrive near to its 

 surface, where they enter into various 

 combinations; the result of th*; is the 

 production of the numerous mineral sub- 

 stances which the earth contains. 



Besides these, who consider an inherent 

 or central fire as necessary to the forma- 

 tion and continuation of this globe, there 

 are others, who refer the particular modi- 

 fication of the form of its surface to the 

 operation of subterraneous fires, acting 

 partially by the incalescence of pyrites 

 and volcanic eruptions, with accompany- 

 ing earthquakes ; amongst those who have 

 adopted this opinion, may be mentioned 

 Steno, Lazare, Moro, and Ray. 



To produce the vast effects necessary to 

 give form to a planet, or to modify its sur- 

 face anew, must of course require the 

 most powerful physical agents. In the va- 

 rious systems, therefore, which human in- 

 genuity has devised, with the hope of 

 pointing out the natural means which have 

 been employed in these prodigious ope- 

 rations, the powerful agency of fire or of 

 water has been generally referred to; 

 and hence geologists have been rather 

 whimsically named, according to the par- 

 ticular agency which they have supported 

 in their discussions, Plutonists, and Nep- 

 tunists. The systems already here no- 

 ticed, it is obvious, are those in which fire 

 has been adopted as almost the sole agent ; 

 in those which next will engage our at- 

 tention, recourse has been had to the 

 combined powers of both agents. 



Dr. Bur net, whose system manifests a 

 considerable portion both of ingenuity 

 and judgment, supposes the earth to have 

 originally been a fluid mass, the compo- 

 nent parts of which became arranged ac- 

 cording to their gravity ; hence the hea- 

 viest matters were deposited at the cen- 

 tre, and above these were disposed, in 

 concentric layers, the substances which 

 were less and less heavy, and on the sur- 

 face was the earth, covered all round by 

 the water, which was itself invested by an 

 unctuous matter, around which existed the 

 circumambient air. By the subsequent in- 

 termixture of the oily matter and earth, and 

 other arrangements of its several compo- 

 nent parts, the crust of earth acquired a 

 smooth form, and obtained those qualities 

 which were necessary for the existence of 

 organized beings. At this period, the axis of 

 the globe was supposed to be parallel with 



that of its orbit, the days and the nights to 

 be equal in length, and a uniform season 

 to have existed, resembling a perpetual 

 spring ; but on the crust of the earth dry- 

 ing, from the ardency of the heat, it be- 

 came violently rent asunder, falling into, 

 and giving openings for the vast abyss of 

 waters beneath : hence the axis of the 

 globe became inclined, occasioning those 

 changes of the seasons, and of the length 

 of the days and nights which now exist ; 

 and thus also were produced the beds of 

 the ocean, with the vallies and the nume- 

 rous mountainous elevations 



Mr. Whiston conjectured, that the earth 

 was originally a comet, which, at the pe- 

 riod mentioned in the Mosaic account as 

 that of the creation of the world, had its 

 orbit rendered nearly circular, and such 

 an arrangement formed of its component 

 parts, as made it fit for the existence of the 

 vegetable and animal creation : having ex- 

 isted in this state its allotted time, he sup- 

 poses a comet to have passed so near to 

 the earth, as to have involved it in the va- 

 pours forming its tail, and which, being 

 condensed, fell in torrents, and produced 

 the deluge described by Moses ; the ac- 

 tion of the comet on the earth itself hav- 

 ing been sufficient to produce, at the 

 same time, those irregularities of its sur- 

 face, which form chains of mountains and 

 the vast beds of the ocean. 



Mr. Pallas, having assumed the forma- 

 tion of the sea and the primitive rocks, 

 supposed that, with the sand produced by 

 their constant disintegration, the sea must 

 have deposited such inflammable and fer- 

 ruginous matters, as, being disposed in. 

 beds on the granite, would form the fuel 

 of volcanoes ; these, raising and bursting 

 the solid beds under which they had ex- 

 isted, and which they must have altered 

 by fusion or calcination, would raise up 

 the mountains of schist and of lime-sione. 

 The shores of the sea bt ing gradually 

 augmented, the sea being diminished and 

 driven back, whilst its bed was ruised in 

 different parts by the power of volcanoes, 

 the formation of the mountains containing 

 petrifactions would take place. Lastly, 

 he supposed, after the earth had been well 

 stocked with vegetables and animals, that 

 by some enormous eruptions at the bot- 

 tom of the sea, its waters may have been 

 made to inundate the whole horizontal 

 surface of the earth, and even those moun- 

 tains which have not exceeded one hun- 

 dred toises in height. 



The system of Dr. Button resembles, 

 in many points, that which has been just 

 noticed; but its several pans are better 

 connected, and it certainly possesses, al* 



