Cherty Lime-rock^ or Corniferous Lime-rock. 61 



Owing to some oversight in my last communication, the name 

 of the Paracels was printed in the observations on the methods 

 for avoiding the heart of this storm, instead of the rocks or shoals 

 called the Pratas, which were intended. 



New York, February 19th, 1839. 



Art. TV.— Cherty Lime-rock, or Corniferous Lime-rock, proposed 

 as the line of reference, for State Geologists of New York and 

 Pennsylvania ; by Amos Eaton, Senior Professor of Rensse- 

 laer Institute, and Professor of Civil Engineering. 



Troy, N. Y., February 9th, 1839. 



TO PROFESSOR SILLIMAN. 



I WAS one of your earliest correspondents on Geology ; conse- 

 quently it is to be presumed, that I have introduced more errors 

 to the public, through your Journal, than any other individual. 

 In truth I consider your 35 volumes as a fair exhibition of the 

 birth, boyhood, and green manhood of geological science in Amer- 

 ica. 



This article is intended chiefly for an auxiliary in aid of those 

 who wish to discuss the adverse views of my friends, Conrad and 

 Rogers, which were referred to in your last number, while pur- 

 suing their investigations into the true order of superposition, 

 among the rocks of New York and Pennsylvania. As my age 

 and infirmities may soon drive me into the state of " untried be- 

 ing," I will give a concise account of some facts familiar to me, 

 which might cost those gentlemen and other geologists much la- 

 bour and travel. 



They being state officers of high responsibility, I shall not ask 

 them to receive my suggestions as of any other authority, than as 

 they may guide their footsteps to localities, which may be useful 

 in their inquiries. 



The lime-rock which I have called corniferous, extends from 

 Lake Erie easterly and southerly, throughout most of the district 

 in question. Its characters are so unequivocal, that it is recog- 

 nized at sight, throughout its whole line, of about five hundred 

 miles. It is a gray rock, often inclining to dark brown. Its color 

 gave the name to the village of Black Rock, at the outlet of Lake 



