ii4 The Founders of Geology LECT. 



fore, confined to what lie could see there, and so little was 

 then known of the geological structure of the globe as a 

 whole, that he could not add much to his acquaintance 

 with the subject by reading what had been observed by 

 others. With this slender stock of acquirement, he adopted 

 the old idea that the whole globe had once been sur- 

 rounded with an ocean of water, at least as deep as the 

 mountains are high, and he believed that from this ocean 

 there were deposited by chemical precipitation the solid 

 rocks which now form most of the dry land. He taught 

 that these original formations were universal, extending 

 round the whole globe, though not without interruption, 

 and that they followed each other in a certain order. He 

 affirmed that the first-formed rocks were entirely of 

 chemical origin, and he called them Primitive, including 

 in them granite, which was the oldest, gneiss, mica-slate, 

 clay-slate, serpentine, basalt, porphyry, and concluding with 

 syenite as the youngest. Succeeding these came what he 

 afterwards separated as the Transition Eocks, consisting 

 chiefly of chemical productions (grey wacke, grey wacke -slate 

 and limestone), but comprising the earliest mechanical 

 depositions, and indicating the gradual lowering of the level 

 of the universal ocean. Still newer, and occupying, on the 

 whole, lower positions, marking the continued retirement 

 of the waters, were the Floetz Eocks, composed partly of 

 chemical, but chiefly of mechanical sediments, and includ- 

 ing sandstone, limestone, gypsum, rock-salt, coal, basalt, 

 obsidian, porphyry, and other rocks. Latest of all came 

 the Alluvial series, consisting of recent loams, clays, sands, 

 gravels, sinters, and peat. 



This system was not put forward tentatively as a 



