362 CAMBRIAN AND SILURIAN IX EUROPE. [XV. 



(the Upper Cambrian of Sedgwick). These rocks, with the 

 Llandcilo at their base, were, in fact, identical with the Bala 

 group studied by the latter in North Wales, and are now 

 clearly traced through all the intermediate distance. This is 

 admitted by Murchison, who says : " The first rectification of 

 this erroneous view was made in 1842 by Professor Ramsay, 

 who observed, that instead of being succeeded by lower rocks 

 to the north and west, the Llandeilo flags folded over in those 

 directions, and passed under superior strata, charged with 

 fossils which Mr. Salter recognized as well-known types of the 

 Caradoc or Bala beds." (Siluria, 4th ed., p. 57, foot-note.) 



The true order of succession in South Wales was, in fact : 

 1. Llandeilo ; 2. Cambrian (= Caradoc or Bala) ; 3. Wenlock 

 and Ludlow ; 4. Old Red sandstone ; the Caradoc or Bala beds 

 being repeated on the two sides of the anticlinal, but in great 

 part concealed on the southeast side by the overlapping May 

 Hill or Upper Llandovery rocks. These latter, as has been 

 shown, form the true base of the upper series which, in the 

 Silurian sections, was represented by the Wenlock and Ludlow. 

 Murchison had, by a strange oversight, completely inverted 

 the order of his lower series, and turned the inferior members 

 upside down. In fact, the Llandeilo flags, instead of being, as 

 he had maintained, superior to the Cambrian (Caradoc or Bala) 

 beds, were really inferior to them, and were only made Silurian 

 by a great mistake. The Caradoc, under different names, was 

 thus made to do duty at two horizons in the Silurian system, 

 both below and above the Llandeilo flags. Nor was this all, 

 for by another error, as we have seen, the Caradoc in the latter 

 position was made to include the Pentamerus beds of the un- 

 confonnably overlying series. Thus it clearly appears that 

 with the exception of the relations of the Wenlock and Lud- 

 low beds to each other and to the overlying Old Red sand- 

 stone, which were correctly determined, the Silurian system of 

 Murchison was altogether incorrect, ami was moreover based 

 upon a series of stratigraphical mistakes which are scarcely 

 paralleled in the history of geological investigation. 



It was thus that the Lower Silurian was imposed on the 



