Williams] EARLY CLASSIFICATIONS OF ROCKS. 19 



will give the best idea of the state of opinion in this first period of geo- 

 logical science. The rocks were classified at the beginning of the cen- 

 tury by the Wernerian school into Primary and Secondary rocks ; the 

 idea contained in this distinction was, for the first, those rocks which 

 were originally deposited from chemical solution and by evaporation 

 from the ocean waters, and the Secondary were those which were pro- 

 duced by water erosion and reshaping of the Primary rocks, and depo- 

 sition of the sediments above them. In the Secondary series fossils 

 were observed, but the Primary series was supposed to have been laid 

 down before the existence of organisms upon the earth. As observa- 

 tions accumulated, the rocks called Primary were found to include some 

 which are now placed in the Paleozoic series. The name Transition 

 came into use as a designation for the rocks, which were known to be 

 stratified and occasionally to contain fossils, occupying a position be- 

 tween the original Primary and Secondary formations. The Germans 

 applied the name "Grauwacke" to this Transition series, and we find 

 in Eaton's classification, as presented in his " Index to the Geology of 

 the Northern States," his " Erie Canal rocks," and his other papers, the 

 use of the term " Grauwacke w in a sense which is different from that 

 originally applied, but one necessitated by the discovery of the same 

 kind of rocks at undoubtedly different horizons. The "Grauwacke" 

 of Eaton was spoken of as " First," " Second," and "Third Grauwacke," 

 etc., and we find him identifying the great mass of the rocks of western 

 New York as belonging to the " Third Grauwacke," which he placed in 

 the Secondary class. This " Third Grauwacke " is placed above the 

 Carboniferous, and also above the " Saliferous rocks," a name which he 

 used to represent the English Saliferous group, but which he identified 

 with the Onondaga Salt group or Salina of the New York system. This 

 was placed above the Conglomerates in the order of sequence because 

 the " Millstone Grit," which they were supposed to represent in the 

 English series, was below the New Red sandstone. 



The imperfection in the methods of correlation of this time is well 

 illustrated by Eaton's identification of the "Old Red sandstone" in 

 New York. 



In "Erie Canal rocks," 1824, "Old Red sandstone" is placed at the 

 top of the "Transition class." It included the " Red sandstone of the 

 Connecticut River," and the "Red sandstone of the Catskill Moun- 

 tains," and in 1820 he reported the "Old Red sandstone" as outcrop- 

 ping in the Niagara gorge. 



This example shows that the color and composition were the basis of 

 correlation, and that the belief that the order or sequence of formations 

 must be the same in New York as in Great Britain led to the erroneous 

 classification. 



This confusion is due not so much to poor observation, which Eaton 

 can not be charged with, as to erroneous theories which were common 

 to geologists in his time. The recognition of the position of the Car- 



