and the Palaeozoic System of England, 493 



Author of the '^ System " ever made during his long, well-fought 

 battles in the geological field. As a matter of fact also, it was 

 known that many thousand feet below the level, where in his own 

 sections he had placed his base line, the same old Cambrian types 

 existed in abundance. Hence, from the very first, the Silurian 

 nomenclature was over-ambitious. The so-called Silurian groups 

 (upper and lower) never made a " System •'' and the only way to 

 obtain a true sectional and palseontological " System '^ out of 

 them, is to contract their base to the May Hill sandstone, and 

 then the " System ^^ (if it must be so called) may remain secure. 



All the previous details were recently submitted to the Geolo- 

 gical Section of the British Association during its meeting at 

 Liverpool ; but they were preceded by an illustrated synopsis of 

 the successive groups which form the great Cambrian series. 

 This synopsis and its sectional illustration are here omitted, be- 

 cause they would convey little more than an expansion of what 

 has been already published in the November Number of the Phi- 

 losophical Magazine [supra^ p. 362, &c.). 



The following questions were prominently ofifered for discussion. 



1st. Was the Cambrian series based on the evidence of true 

 sections ; were its subdivisions natural, its names geographically 

 appropriate ? Did the sections exhibited make an approach to a 

 good physical analysis of the great Cambrian series ? 



2nd. Was the evidence for the existence of a May Hill group 

 (as entirely distinct from the Caradoc sandstone, and forming 

 the physical and palseontological base of the Wenlock shale, and 

 the so-called Upper Silurian rocks) well established ? 



3rd. Were there indications of great mechanical movements 

 anterior to, or during, the period of the May Hill sandstone ? 

 Were they made probable, sometimes by the existence of conglo- 

 merates, sometimes by a discordancy of position, sometimes by an 

 obvious interruption to the continuity of the deposits ? Or in other 

 words, was not the Silurian series frequently unconformable to 

 the Cambrian ? 



4th. Was there not an immediate and great palseontological 

 change between the fossils of the May Hill sandstone and those 

 of the groups (whatever they might be) on which it rested ? 



To all these questions I have, directly or indirectly, given 'an 

 affirmative reply in this or my previous paper. 



But what were the replies given to them by the gentlemen of 

 the Government Survey, and by some other distinguished geolo- 

 gists who were present ? Every one who spoke had already been 

 in some form or other committed to what I am now certain is an 

 erroneous, and therefore cannot be a tenable nomenclature ; and 



