THE MAKING OF THE GEOLOGICAL TIME-SCALE. 1 5 



therefore, that he presents a fair idea of the opinions which 

 underlay the Lehmann classification. According to Kirwan's 

 book the rocks were originally in a soft or liquid state, the 

 centre of the earth was supposed to be hollow, or the whole 

 earth was a solid exterior crust with immense empty caverns 

 within. The materials of the earth were then in a state of 

 fusion or solution, and by condensation, as time progressed, 

 the solids were crystallized out and deposited from the chaotic 

 fluid. The water contracted its surface and lowered upon it 

 by sinking into the interior cavities. With the deposition of 

 the primitive rocks from the chaotic fluid, the water became 

 purer. Mountains were conceived of as the local points of 

 original crystallization which drew to them, in the process, 

 the minerals from the general fluid. As the waters gradually 

 withdrew by evaporation and sinking into the interior caverns, 

 they became clarified and capable of supporting organic life. 



Kirwan says:* "The level of the ancient ocean being 

 lowered to the height of 8500 or 9000 feet, then, and not 

 before, it began to be peopled with fish." (Under the name 

 fish he included shell-fish and all other petrifactions.) The 

 plains were formed of depositions from the water of argilla- 

 ceous, siliceous, and ferruginous particles, mingled with those 

 derived by erosion from the already protruding mountains. 

 All the rocks above the height mentioned, he observed, quot- 

 ing from testimony of numerous travellers, "are lacking in fos- 

 sils ; even the limestones are crystalline or ' primitive ' lime- 

 stones and marbles." These observations were cited in refuta- 

 tion of Button's " error " in claiming that all limestones were 

 derived from comminuted shells. According to some author- 

 ities, primitive mountains should include rocks of even less 

 height than 8000 feet, and the occasional presence of fossils 

 at a greater elevation was by them accounted for by their 

 transference to that elevation by the deluge. 



Geological Mountains (Gebirge) and Formations. This account 

 of Kirwan's will suggest the way by which the rock formation 

 first came to be called " Gebirge " or mountains. Rocks were 

 supposed to lie as they were originally formed, and thus in 



* " Geological Essays," p. 26. 



