SEQUEL TO SYSTEMATIC GEOLOGY. 535 



6e found in India, we require to be assured that these formations are, 

 in some way, the equivalents of their synonyms in countries better 

 explored. Till this is done, the results of observation in such places 

 would be better conveyed by a nomenclature implying only those facts 

 of resemblance, difference, and order, which have been ascertained in 

 the country so described. We know that serious errors were incurred 

 bv the attempts made to identify the Tertiary strata of other countries 

 with those first studied in the Paris basin. Fancied points of resem- 

 blance, Mr. Lyell observes, were magnified into undue importance, and 

 essential differences in mineral character and organic contents were 

 slurred over. 



[2nd Ed.] [The extension of geological surveys, the construction of 

 geological maps, and the determination of the geological equivalents 

 which replace each other in various countries, have been carried on in 

 continuation of the labors mentioned above, with enlarged activity, 

 range, and means. It is estimated that one-third of the land of each 



o ' 



hemisphere has been geologically explored ; and that thus Descriptive 

 Geology has now been prosecuted so far, that it is not likely that even 

 the extension of it to the whole globe would give any material novelty 

 of aspect to Theoretical Geology. The recent literature of the subject 

 is so voluminous that it is impossible for me to give any account of it 

 here ; very imperfectly acquainted, as I am, even with the English 

 portion, and still more, with what has been produced in other 

 countries. 



While I admire the energetic and enlightened labors by which the 

 philosophers of France, Belgium, Germany, Italy, Russia, and America, 

 have promoted scientific geology, I may be allowed to rejoice to see in 

 the very phraseology of the subject, the evidence that English geolo- 

 gists have not failed to contribute their share to the latest advances in 

 the science. The following order of strata proceeding upwards is now, 

 I think, recognized throughout Europe. The Silurian ; the Devonian 

 (Old Red Sandstone ;) the Carboniferous ; the Permian, (Lower part 

 of the new Red Sandstone series ;) the Trias, (Upper three members 

 of the New Red Sandstone series ;) the Lias ; the Oolite, (in which 

 are reckoned by M. D'Orbigny the Etages Bathonien, Oxonien, Kim- 

 meridgien, and Portlandien ;) the Neocomien, (Lower Green Sand,) 

 the Chalk ; and above these, Tertiary and Supra-Tertiary beds. Of 

 these, the Silurian, described by Sir R. Murchison from its types in 

 South Wales, has been traced by European Geologists through the 

 Ardennes, Servia, Turkey, the shores of the Gulf of Finland, the valley 



