Ca VIII.] NEPTUNIAN" THEORY. 91 



planet had become the habitation of animals and plants. This bold 

 generalization, although anticipated in some measure by Steno, a century 

 before, in Italy, formed at the time an important step in the progress of 

 geology, and sketched out correctly some of the leading divisions into 

 which rocks may be separated. About half a century later, Werner, so 

 justly celebrated for his improved methods of discriminating the minera- 

 logical characters of rocks, attempted to improve Lehman's classification, 

 and with this view intercalated a class, called by him " the transition 

 formations,"" between the primitive and secondary. Between these last 

 he had discovered, in northern Germany, a series of strata, which in their 

 mineral peculiarities were of an intermediate character, partaking in 

 some degree of the crystalline nature of micaceous schist and clay-slate, 

 and yet exhibiting here and there signs of a mechanical origin and or- 

 ganic remains. For this group, therefore, forming a passage between 

 Lehman's primitive and secondary rocks, the name of ubergang or transi- 

 tion was proposed. They consisted principally of clay-slate and an ar- 

 gillaceous sandstone, called grauwacke, and partly of calcareous beds. 

 It happened in the district which Werner first investigated, that both the 

 primitive and transition strata were highly inclined, while the beds of 

 the newer fossiliferous rocks, the secondary of Lehman, were horizontal. 

 To these latter therefore, he gave the name of Jlotz, or " a level floor ;" 

 and every deposit more modern than the chalk, which was classed as the 

 uppermost of the flotz series, was designated " the overflowed land," an 

 expression which may be regarded as equivalent to alluvium, although 

 under this appellation were confounded all the strata afterwards called 

 tertiary, of which Werner had scarcely any knowledge. As the followers 

 of Werner soon discovered that the inclined position of the " transition 

 Deds," and the horizontally of the flotz, or newer fossiliferous strata, were 

 mere local accidents, they soon abandoned the term flotz ; and the four 

 divisions of the Wernerian school were then named primitive, transition, 

 secondary, and alluvial. 



As to the trappean rocks, although their igneous origin had been al- 

 ready demonstrated by Arduino, Fortis, Faujas, and others, and especially 

 by Desmarest, they were all regarded by Werner as aqueous, and as mere 

 subordinate members of the secondary series.* 



The theory of Werner's was called the " Neptunian," and for many 

 years enjoyed much popularity. It assumed that the globe had been at 

 first invested by a universal chaotic ocean, holding the materials of all 

 rocks in solution. From the waters of this ocean, granite, gneiss, and 

 other crystalline formations, were first precipitated ; and afterwards, when 

 the waters were purged of these ingredients, and more nearly resembled 

 those of our actual seas, the transition strata were deposited. These were 

 of a mixed character, not purely chemical, because the waves and currents 

 had already begun to wear down solid land, and to give rise to pebbles, 

 sand, and mud ; nor entirely without fossils, because a few of the first 

 marine animals had begun to exist. After this period, the secondary for- 

 * See Principles of Geology, vol. i. chap. iv. 



