

CHAPTER I. 



THE HISTORY AND DEVELOPMENT OF OPINIONS REGARDING 

 THE CLASSIFICATION OF ROCKS IN THE UNITED STATES FROM 

 THE TIME OF WILLIAM MACLURE TO THE COMPLETION OF 

 THE GEOLOGICAL SURVEY OF THE STATE OF NEW YORK, 

 1809-1843. 



An article appeared in the Trans. Am. Phil. Soc., in the year 1809, 1 

 which is among the earliest careful expositions of the systematic 

 arrangement of the rocks of North America, if not the very earliest. 2 



The classification adopted by Maclure is the Wernerian, and he de- 

 feuds the usage of this system by the following arguments 3 : "First, 

 because it is the most perfect and extensive in its general outlines ; 

 and secondly, the 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 to be the most correct elucidation 

 of the general exactitude of that theory as respects the relative position 

 of the different series of rocks." 



The following is the nomenclature adopted : l 



Class 1. Primitive rocks. — (1) Granite, (2) Gneiss, {6) Mica slate, (4) Clay slate, (5) 

 Primitive limestone, (6) Primitive trap, (7) Serpentine, (8) Porphyry (9) Syenite, 

 (10) Topaz rock, (11) Quartz rock, (12) Primitive flinty slate, (13) Primitive gypsum, 

 (14) White stone. 



Class 2. Transition rocks. — (1) Transition limestone, (2) Transition trap, (3) Grey- 

 vracke, (4) Transition flinty slate, (5) Transition gypsum. 



Class 3. Floetzor Secondary rocks. — (1) Old Red sandstone or first saudstone forma- 

 tion, (2) First or oldest Floetz limestone, (3) First or oldest Floetz Gypsum, (4) 

 Second or Variegated sandstone, (5) Second Floetz gypsum, (6) Second Floetz 

 limestone, (7) Third Floetz sandstone, (8) Rock Salt formation, (9) Chalk formation, 

 (10) Floetz Trap formation, (11) Independent Coal formation, (12) Newest Floetz 

 Trap formation. 



Class 4. Alluvial rocks. — (1) Peat, (2) Sand and gravel, (3) Loam, (4) Bog iron ore, 

 (5) Nagel fluh, (6) Calc tuff, (7) Calc sinter. 



It is singular to notice how persistently this original error of placing 

 the " Coal formation " high up in the " Secondary " was perpetuated by 

 later geologists. So, too, the position of the u Kock Salt formation," 

 which was in the Mesozoicin England, was erroneously regarded, when 



1 Vol. 6, pp. 411-428. 



2 The article is entitled "Observations on the geology of the United States, explanatory of a 

 geological map, by William Maclure, read January 20,1809." For students of early maps, it is well 

 to remember this map of Maclure's in the Tranasctiona. 



3 0p.cit.,pp.411,412. 



♦Ibid., p. 412. 

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