J. I) Dana — SSDGWICX am» MUROHISON. L79 



tin- evidence, American as well as European, naturally grav- 

 itated in the Murchisoni&n direction, while applauding the 

 work of Sedgwick. 



In 1853, Mr. Salter showed, by a study of the fossils/ that 

 the Bala W(\> from Bala in Merioneth, the original Bala, were 

 included within the period of the Caradoo. Sedgwick sub- 

 sequently (in the preface to the Catalogue of the Wood wardian 

 Museum by J. W, Salter), divided his Upper Cambrian into 

 (1) The L<>ir,r Bala,tO include the Llandeilo flags (Upper 

 Llandeilo of the Geological Survey, the Arenig being the 

 Lower); (2) the Middle Bala, corresponding to the Caradoc 

 sandstone, the Bala rocks, and the Coniston limestone (Geo- 

 logical Survey) ; and the Upper Bala or the Caradoc-shales, 

 Hirnant limestone and the Lower Llandovery."f 



In 1854, the Cambrian system not having secured the place 

 claimed for it, Sedgwick brought the subject again before the 

 Geological Society. Besides urging his former arguments, he 

 condemned Murchisons work so far as to imply that none of 

 his sections '"give a true notion of the geological place of the 

 groups of Caer Caradoc and Llandeilo " ; and to speak of the 

 Llandeilo beds, in a note, as "a remarkable fossiliferous group 

 (about the age of the Bala limestone) of which the geological 

 place was entirely mistaken in the published sections of the 

 Silurian System." There were errors in the sections, and that 

 with regard to the May Hill group was a prominent one ; but 

 this was sweeping depreciation without new argument ; and, in 

 consequence of it, part of the paper was refused publication 

 by the Geological Society. 



The paper appeared in the Philosophical Magazine for 1854.;); 

 It contains no bitter word, or personal remark against Mur- 

 chison. Sedgwick was profoundly disappointed on finding, 

 when closing up his long labors, that the Cambrian system had 

 no place in the geology of the day. He did not see this to be 

 the logical consequence of the facts so far as then understood. 

 It was to him the disparagement and rejection of his faithful 

 work ; and this deeply moved him, even to estrangement from 

 the author of the successful Silurian system. 



Conclusion. 



The ground about which there was reasonably a disputed 

 claim was that of the Bala of Sedgwick's region and the 

 Llandeilo and Caradoc of Mnrchison's. Respecting this com- 

 mon field, long priority in the describing and defining of the 



* Q. J. Geol. Soc , i. 62. 



f Cited from Etheridge, in Phillips' Geology, ii, 77, 1885. 



\ Fourth series, volume viii, pages 301. 359, 481. 



