432 HISTORY OF GEOLOGY AND PALAEONTOLOGY. 



Deshayes, Lyell, and Bronn had thus verified the import- 

 ance of comparative study in defining a successive series of 

 palaeontological horizons within each larger group of rock- 

 strata. The security of the method, and its community of 

 interest with zoological studies, lent a new fascination to 

 the stratigraphical aspects of geology. The subject promised 

 a good field of research, and attracted some of the most acute 

 intellects of Europe into its service. The part of the geologi- 

 cal record which still remained very obscure was the so-called 

 "Transitional" series below the Carboniferous rocks embracing 

 the thick greywacke formation with interbedded shales, slates, 

 conglomerates, and limestone. This group still retained its 

 Wernerian appellation in literature, although many authors 

 had comprised under it some of the "Primitive" rocks in 

 Werner's system (ante, p. 58). Continental authors had con- 

 tributed memoirs on the Harz mountains, on Gothland, the 

 Rhine and Belgian areas of "Transitional" rocks, and had 

 erected stratigraphical sub-divisions of a local value formed 

 chiefly on petrographical characteristics ; but no complete 

 sub-division of the immense complex of strata between the 

 crystalline schists and the coal measures had been attempted. 



This was the gigantic task which two British geologists, 

 Adam Sedgwick 1 and Roderick Murchison, 2 set themselves 



1 Adam Sedgwick, born on the 22nd March 1785. at Dent in Yorkshire, 

 the son of a clergyman, studied theology and mathematics in Cambridge ; 

 in 1809 became an assistant demonstrator at Trinity College, and in 1818 

 Professor of Geology at the University of Cambridge. In 1822 he began 

 his researches in Cumberland ; in 1826 made his first journey with Roderick 

 Murchison to Scotland, and worked for ten years along with Murchison, 

 until the difference of opinion about the Cambrian formation embittered 

 their friendship. Sedgwick was a born teacher ; his lectures, full of en- 

 thusiasm and relieved by a ready sense of humour, stimulated many of the 

 younger men to devote themselves to geology ; he was also the founder of 

 a rich geological museum in Cambridge, whose scientific value was highly 

 eulogised when the Wollaston and Copley medals were conferred on him. 

 Sedgwick died on the 27th January 1873, in Cambridge. 



2 Roderick Impey Murchison, born on the 1 9th February 1792, at 

 Tarradale in the Scottish Highlands, was trained at Great Marlow for 

 a military career, and was an officer in the Spanish campaign of 1807. 

 He married in 1815 the accomplished daughter of General Hugonin, who 

 encouraged him to follow out his bent for science. After short preparatory 

 studies, Murchison began his literary activity with several memoirs on the 

 geology of Sussex, the north of Scotland, and Arran ; he travelled in 1828 

 with Lyell in France and Upper Italy, and together with Sedgwick 

 made detailed geological studies in the Austrian and Bavarian Alps. In 

 1831 he began his famous investigations of the Palaeozoic deposits in Wales 



