XV.] CAMBRIAN AND SILURIAN IN EUROPE. 363 



scientific world ; and we may well ask, with Sedgwick, wheth- 

 er geologists " would have accepted the Lower Silurian classifi- 

 cation and nomenclature had they known that the physical or 

 sectional evidence upon which it was based had been, from the 

 first, positively misunderstood." Feeling that his own sections 

 were, as has since been fully established, free from error, Sedg- 

 wick naturally thought his name of Upper Cambrian should 

 prevail for the great Bala group. Hence the long and imbit- 

 tered discussion that followed, in which Murchison, in many 

 respects, occupied a position of vantage as against the Cambridge 

 professor, and finally saw his name of Lower Silurian supplant 

 almost entirely that of Upper Cambrian given by Sedgwick, 

 who had first rightly defined and interpreted the geological 

 relations of the group. 



In a paper read before the Geological Society in June, 1843, 

 (Proc. Geol. Soc., IV. 213- 223) when the perplexity in which 

 the relations of the Upper Cambrian and Lower Silurian rocks 

 were involved had not been cleared up by the discovery of 

 Murchison' s errors in stratigraphy, Sedgwick proposed a com- 

 promise, according to which the strata from the Bala limestone 

 to the base of the Wenlock were to take the name of Cambro- 

 Silurian ; while that of Silurian should be reserved for the 

 Wenlock and Ludlow beds, and for those below the Bala the 

 name of Cambrian should be retained. The Festiniog group 

 (including what were subsequently named the Lingula flags 

 and the Tremadoc slates) would thus be Upper instead of 

 Middle Cambrian, the original Upper Cambrian being hence- 

 forth Cambro-Silurian ; it being understood that, wherever the 

 dividing line might be drawn, all the groups above it should 

 be called Cambro-Silurian, and all those below it Cambrian. 

 This compromise was rejected by Murchison, who in the map 

 accompanying the first edition of his Siluria, in 1854, extended 

 the Lower Silurian color so as to include all but the lowest 

 division of the Cambrian, namely, the Bangor group. "When, 

 however, the relations of Upper Cambrian and Silurian were 

 made known by the discoveries of Sedgwick and the govern- 

 ment surveyors, this compromise was seen to be uncalled for, 



