Geological Nomenclature. 145 



Art. XXI. — Geological Nomenclature, Classes of Rocks, 

 SfCj by Prof. Amos Eaton. 



In tlje first part of the Erie Canal survey, I attempted a 

 Geological Nomenclature, so far as the rocks described in 

 that survey required one. The facts upon which it was 

 founded, were all collected more than four years ago. Since 

 it was published, I have reviewed the whole line several 

 times, and have traced the strata laterally to a considerable 

 extent. Several gentlemen, who are familiar with such in- 

 vestigations, have devoted much time and attention to the 

 same subject, and have favored me with their results.* 



Before entering upon the subjects which exclusively ap- 

 pertain to the second part, I shall introduce some facts in 

 support of the Geological Nomenclature proposed in the 

 preceding synopsis. I published a tabular view in the 2d 

 No. of the 13th vol. of the American Journal of Science, 

 with a view to elicit criticisms. Fortunately I succeeded 

 beyond my expectations, Prof. Parker Cleaveland favored 

 me with one hundred and three very judicious queries. Dr. 

 Steele of Saratoga presented facts and a suit of specimens, 

 which totally changed my former views of the oolitic forma- 

 tion. Through the politeness of several others, my views 

 were corrected on numerous points. 



But the characters and order of superposition, are so 

 manifest in this district, that an attentive observer, of but 

 ordinary pretensions, could scarcely fall into very great mis- 

 takes, especially in the secondary formation. 



I take for my starting points, the Highlands on the Hud- 

 son River, a traverse across Rensselaer County, from the 

 west line of Massachusetts to the Hudson, and the Genessee 

 Falls. 



The Highlands being cut down to their base, in a trans- 

 verse direction by the Hudson, we cannot conceive of a bet- 

 ter exhibition of primitive rocks. The central part is here 

 occupied by slaty granite (gneiss) embracing alternating 



* Mr. G. W. Clinton and Dr. I. Eights, have furnished very important 

 facts. Profs. Beck, Henry, Rafinesque, Patten, and Benedict, have communi- 

 cated whatever fell in their way from time to time. More than twenty other 

 scientific gentlemen have occasionally contributed useful materials. I should 

 add, that on account of a temporary indisposition, Mr. Clinton assisted in col- 

 lating localities, and in preparing materials for this nomenclature. 

 Vol. XIV.— No. 1. 19 



