14 GEOLOGICAL BIOLOGY. 



These were the formations which made up the geological 

 series as then recognized. Volcanic rocks were looked upon 

 as local formations, and of small account in general classifica- 

 tion. But they came to be more deeply studied by Werner, 

 and his notion that trap was of aqueous origin led to much 

 controversy, and gave chief prominence to his views (the 

 Neptunian theory) and to that classification of rocks which will 

 be next considered. The rocks of igneous origin, although 

 sometimes interstratified with sedimentary rocks, do not enter 

 into the present geological time-scale, and for the present 

 purpose further consideration of their classification is unneces- 

 sary. There has always been a remnant of rocks at the base 

 of the scale, the consideration of which may be discarded 

 here, because it is chronologically known only as below those 

 rocks of which distinct evidence of their relative age is appar- 

 ent. The name Primitive has been changed to Primary, and 

 finally to Archaean, a name which was proposed by Dana,* 

 and is likely to be permanently retained for some of the basal 

 part of the series. 



This first comprehensive classification of rocks may be 

 called the Lehmann classification. It was based upon a 

 structural analysis of the rocks in the order of their actual 

 positions. The nomenclature is applied on the theory of 

 relative order of formation. 



Richard Kirwan and Geology at the Close of the Last Century. 

 Richard Kirwan f claimed to be the first author to publish a 

 general treatise on Geology in the English language. Al- 

 though the book is written in a decidedly controversial spirit, 

 the author appears to have had a thorough acquaintance with 

 the various treatises in French, German, Latin, and English, 

 in which were expressed contemporaneous opinions regarding 

 geological science. He was a Fellow of the Royal Societies 

 of London and Edinburgh, member of the Royal Irish Acad- 

 emy, and of Academies in Stockholm, Upsala, Berlin, Man- 

 chester, and Philadelphia, and Inspector General of his 

 majesty's mines in the kingdom of Ireland. It is probable, 



* Amer. Jour. Sci., vm. 213, 1874. 

 f "Geological Essays," London, 1799. 



