1 1 6 The Cambrian and 



where my friend has determined the true relations of the Llandeilo 

 flag to the beds above it and below it, so as to define its place in 

 a general section of Wales, whether real or ideal. I offer no 

 criticism " on two or three mistakes ;" I affirm that the whole 

 conception of the relations of the Llandeilo flag to my Upper 

 Cambrian group was erroneous ; and that all the lower parts of 

 my friend's general and ideal sections — the very foundations of 

 his Silurian nomenclature — were wrong in principle. 



3. In the same paragrapli my friend adds, " that the inferiority 

 of position (viz. of the Upper Cambrian or Upper Bala group to 

 the Llandeilo flag) has proved to be a fundamental misconception." 

 True ; but with whom rests the blame of this fundamental mis- 

 conception ? Any man of common sense reading this paragraph, 

 must conclude that the mistake was mine. But wliat is the fact ? 

 I made no mistake whatsoever when I affirmed that what I for- 

 merly called my Upper Cambrian system overlaid the Bala lime- 

 stone. That the same groups of Upper Cambrian strata under- 

 laid the Llandeilo flag, was the " fundamental misconception" of 

 my friend ; and he must bear the blame of it. The mistake I 

 made was the adoption, during fourteen years, of this fundamental 

 error on the sole authority of my friend. 



4. At the end of the same paragraph he adds as follows : " In 

 the hands of the Government geological surveyors, the Cambria of 

 Sedgwick, which was undefined and unknown through any publi- 

 cation of its fossils, has proved to be identical in age with the 

 original published Siluria of Murchison." Any plain, unsophis- 

 ticated reader must conclude, I think, from such words as these, 

 that in the interpretation of the Cambrian sections I had made 

 some great radical mistake, and that the sections of my opponent 

 were immaculate. Now t the very reverse of this is the case. The 

 Government surveyors have discovered no great fundamental mis- 

 take in my Welsh sections, while they have completely upset the 

 scheme on which the two Lower Silurian stages were constructed 

 by my friend. To say that the great Cambrian groups are 

 " identical in age with the original published Silurian rocks of 

 Murchison," is so extravagantly inaccurate, that it is no easy 

 matter to describe its inaccuracy in respectful language. My 

 friend might just as well affirm that all the vast series of rocks 

 west of the Berwyns are identical in age with the Bala limestone ! 

 But we may ask, how have the Government surveyors brought 

 the Llandeilo flag of the Silurian system into comparison with the 

 great groups of Cambria ? By a process of development, both 

 upwards and downwards, by adding three or four thousand feet of 

 strata (which had been completely misinterpreted by my friend 

 and antagonist) above the Llandeilo flag, so as to connect it with 

 •the Caradoc sandstone, and then by adding, in a descending sec- 



