414 THE CAMBRIAN. [bull. 81. 



In his extended aud valuable essays upon tbe history of the names 

 Cambrian and Silurian in geology and theTacouic question in geology, 

 and numerous other minor papers, Dr. T. S. Hunt 1 clearly sets forth 

 the description of the various strata referred to the Cambrian and 

 Silurian in America and Europe, and shows by testimony of different 

 writers the relations the various formations sustain to each other, both 

 stratigraphically aud in their geographic distribution. Nearly all, if 

 not all, the original correlations made by him are based upon lithologic 

 data, as he believes in a uniform development and sequence of litho- 

 logic forms from earlier Archean time to the deposition of the fossilif- 

 erous sedimentary rocks. The correlations within the latter are largely 

 made upon their strati graphic, lithologic, and paleontologic characters 

 as mentioned by authors. 



CORRELATIONS WITH EUROPEAN FORMATIONS. 



Numerous correlations were made between the strata of the forma- 

 tions of America and those of Europe by Messrs. Conrad, Owen, Rogers, 

 Troost, Jackson, and others; but it was not until the investigation of 

 M. Edward de Veineuil, in 1847, that correlations were made by one 

 who had personally investigated the formations and fossils, both in 

 Europe and America. 2 



De Verneuil. — He began his comparisons with the view that super- 

 position was the foundation of paleontology; that the only compari- 

 sons that could be made between continents separated by a sea was 

 by a study, in each of them, of a series of beds confined between two 

 zones at well determined points; that their fossils must be compared, 

 and the identical species picked out to see if the species are distributed 

 according to the same laws. He concluded that, if it happens in the 

 two countries that a certain number of s\ stems, characterized by the 

 same fossils, are superimposed in the same order, whatever may be 

 otherwise their thickness and the number of physical groups of which 

 they are composed, it is philosophical to consider these systems as 

 parallel and synchronous. Comparisons were made between the strata 

 in the two countries that occur beneath the coal-bearing or Carbonifer- 

 ous rocks. He noted that the Potsdam sandstone with Lingulais prob- 

 ably analogous to the sandstone with Obolus, of Russia, and the lower 

 sandstones of Scandinavia. u These are in the two continents the 

 most ancient pre-Carboniferous rocks." 



The siliceous limestones, those of Black River and of Trenton, are the equivalents" 

 of a great part of the Lower Silurian stage of Europe, and they occupy the same posi- 



1 History of tbe names Cambrian and Silurian in Geology. Canadian Nat., new ser., vol. 6, 1872, pp. 

 281-312,417-448. The Taconic Question in Geology. Mineral Physiology and Physiography. A sec- 

 ond series of Chemical and Geological Essays. 1886, pp. 517-686. 



a Note sur le parall61isme des roches des depots paleozoiqufis de l'Amerique Scptontrionale avec 

 ceux de l'Europe, suivie ri'un tableau des especes fossiles communes aux deux continents, avec l'indi- 

 cation des etagea ou elles se rencontrent, et terminer par nn examen critique de cbacune de ces espeer.s. 

 Soc. geol. France, Bull., 2 e s6r.,vol. 4, pp. 646-709, 1847. Translated and condensed by Prof. James Hall. 

 Aip. Jour. Sci., 2d ser., vol. 5, 1848, pp. 176-183, 359-370 j vol. 7, 1849, pp. 45-51, 218-231, 





