THE MAKING OF THE GEOLOGICAL TIME-SCALE. 19 



nature and relative situation of the minerals in the United 

 States, whilst they are certainly the most extensive of any 

 field yet examined, may perhaps be found the most correct 

 elucidation of the general accuracy of that theory, so far as 

 respects the relative position of the different series of rocks." * 

 The classification there set forth is as follows (in the order 

 from below upwards) : 



Class I. Primitive rocks. 



Class II. Transition rocks including (i) transition lime- 

 stone, (2) transition trap, (3) greywacke, (4) 

 transition flinty slate, (5) transition gypsum. 

 Class III. Floetz or secondary rocks including (i) old red 

 sandstone, (2) 1st floetz limestone, (3) 1st 

 floetz gypsum, (4) 2d variegated sandstone, 

 (5) 2d floetz gypsum, (6) 2d floetz limestone, 

 (7) third floetz sandstone, (8) rock-salt for- 

 mation, (9) chalk formation, (10) floetz-trap 

 formation, (u) independent coal formation, 

 (12) newest floetz-trap formation. 



Class IV. Alluvial rocks including (i) peat, (2) sand and 

 gravel, (3) loam, (4) bog iron ore, (5) nagel 

 fluh, (6) calc tuff, (7) calc sinter. 



Notice that in this classification the "coal formation" is 

 placed near the top of the secondary rocks, the "rock-salt 

 formation " near its middle, and the " old red sandstone " at 

 its base. Later investigations did not confirm Maclure's 

 opinion of the accuracy 01: Werner's system as applied to 

 American rocks. 



Amos Eaton's Classification of the New York Rocks. f Amos 

 Eaton's classification of the New York rocks is an elaboration 

 of the same system . 



Principles involved in the Wernerian System of Classifica- 

 tion. In each of these classifications, except in *a few cases 

 of the retention of distinctions based upon the structural anal- 

 ysis, the whole nomenclature and classification is based upon 

 mineralogical composition of the rocks. In the succeeding 

 progress of the science a great part of the nomenclature has 

 been replaced by other names composed on a different prin- 



* "Observations, etc.," p. 28. 



f As exhibited in his " Geological and Agricultural Survey of the district 

 adjoining the Erie Canal in the State of New York," Albany, 1824. 



