

18 THE DEVONIAN AND CARBONIFEROUS. [bull. 80. 



posits. William Smith, as all geologists know, early in the century 

 recognized the importance of fossils in identifying geological deposits, 

 and as early as 1812 a map of England and Wales was prepared by him 

 with the order of the geological deposits marked upon it, and it was 

 known, by William Smith, at least, that the several strata were char- 

 acterized by different organisms. The order of these deposits was 

 known by him, and a table was drawn up in 1799, some improvements 

 were made in his map and in his table in 1815 and 1816, and in 1815 a 

 small treatise was published by Smith, entitled "A Geological Table of 

 British Organized Fossils," which identified the course and continuity 

 of the strata. 



It will thus be seen that in the earliest decade of the century there 

 was one man, at least, who recognized the importance of fossils in de- 

 termining and correlating geological strata. The methods of Smith 

 were applied, however, no lower than the Carboniferous system, and it 

 was not until later that they were adopted as a general principle for the 

 classification and systematization of the whole geologic column. 



Although fossils were recognized as important, they were so poorly 

 understood, and so few individuals studying geology had any accurate 

 knowledge even of their generic characters, that they were of very slight 

 service in correlating strata. 



Mineral characters, therefore, played the principal part in all the 

 classifications, correlations, and even nomenclatures of the geologists of 

 the first quarter of this century. 



Much confusion is found, also, in the attempts to generalize, on ac- 

 count of ignorance of the true means of correlating the strata that 

 cropped out in different regions. The early names used indicate the 

 principles of these classifications, such as u Granular limestones," " Ar- 

 gillite," u Grauwacke," " Old Red sandstone," " Oolite," " Cretaceous," 

 44 Magnesian limestones " ; and a great many others could be enumer- 

 ated. These, it will be seen, are all names indicating the usage of min- 

 eral characters for the distinction of the strata, independent of their 

 locality and independent of their order of sequence or position in a ver- 

 tical scale. 



In order to change this system, it was necessary that a careful study 

 of fossils be made, that their biological relations be clearly understood, 

 and that their characters be geographically and geologically known. 

 Th*\ classification of the geological deposits lor England was fairly well 

 understood for the Mesozoic and higher strata as early as 1822, but the 

 lower strata, the Paleozoic series, as we now understand it, were not 

 well understood prior to the works of Murchison and Sedgwick and 

 their associates. Murchison's 44 Silurian system" was not published 

 till 1839, and the classification of the Paleozoic series, although studied 

 by English and Americans between 1830 and 1840, can not be regarded 

 as having been fully understood by geologists until about the year 1840. 



A glance at the general system of classification in the early text books 



