1847.] MURCHISON ON THE SILURIAN ROCKS OF N. WALES, ETC. 167 



if'^d 



y^' 



wacke," which was meant to represent cer- 

 tain inferior urifossiliferous rocks (like those 

 of the Longmynd range of Shropshire). Now 

 on sending a copy of my new classification to 

 M. Elie de Beaumont, that eminent geolo- 

 gist, wishing to mark strata separated by 

 lines of dislocation by separate names, sug- 

 gested the propriety of further distinguish- 

 ing those last-mentioned unconformable and 

 inferior rocks by the term " Hercynian," as 

 taken from the Hartz mountain in Germany, 

 where, as he then believed, the oldest slaty 

 group would prove to be of higher antiquity 

 than the strata to which I had applied the 

 word " Silurian." Unwilling that the name 

 for these infra- Silurian rocks should be 

 taken from a foreign country, in which no 

 precise palaeozoic horizon had then been 

 lixed, I at once urged Professor Sedgwick 

 to apply to his slaty rocks, which were con- 

 fidently believed to be inferior to my own, 

 some term, on the same geographical prin- 

 ciple by which I had been governed in pro- 

 posing " Silurian/' I even ventured to sug- 

 gest the word " Snowdonian," because I 

 knew that my friend then considered the 

 N.W. portion of the Welsh chain to be made 

 up of the oldest fossiliferous masses ; but 

 preferring a more comprehensive geogra- 

 phical name, he took that of " Cambrian." 

 With this arrangement we both felt certain, 

 that no anomaly could be introduced into 

 the lower palaeozoic classification, as the re- 

 lations and fossil contents of mineral masses 

 which v/ere contiguous, must be eventually 

 cleared up without fear of error or the in- 

 troduction of theoretical views. 



The word " Cambrian " (as far as I know) 

 was first used in print by myself in the year 

 1836, in describing the structure of Pem- 

 brokeshire. But whilst I then spoke gene- 

 rally of such Cambrian rocks, and after- 

 wards at greater length in my large volume, 

 their analysis and examination formed no 

 part of my scope ; that task having been 

 specially undertaken by Professor Sedgwick, 

 at a time when I really believed, that from 

 their great thickness, apparent inferiority 

 and different lithological structure, they 

 would be found to contain a suite of orga- 



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