WITH THOSE OF NEW YORK. 281 



appeared entirely, or left only a line of calcareous matter, marked 

 by the presence of Producti. Still higher in this rock are some 

 quan'ies, where a mass of limestone eleven feet thick is wrought 

 for building stone. The lower part of this mass is a compact 

 oolite, while the upper is rather coarsely crystalline with frag- 

 ments of fossils. Below this, and separated by a course of sand- 

 stone of several feet in thickness, is another thick bed of lime- 

 stone, and the whole is succeeded above by sandstone like that 

 below. The height of these quarries above the black shale is 

 fom- hundred and fifty-four feet; and the thickness of shales and 

 sandstones between this point and the main limestone above, is 

 fifty or sixty feet more.* 



These rocks are marked in the section by the name of sub-car- 

 boniferous, and although the fossils, and the character of the 

 intercalated beds of limestone, indicate the commencement of 

 the same era as the carboniferous limestone, yet it requires that 

 a limit should be fixed between what is to be strictly referred to 

 the Carboniferous period, and older deposites. The gray sand- 

 stone here spoken of contained in numerous localities a large 

 species of Productus, resembling P. hemispherica, a carbonifer- 

 ous fossil, while there seemed to be a gradual transition from 

 rocks of the Chemung group to those above, indicating no cessa- 

 tion of deposition, and scarcely a change in lithological char- 

 acter, except the occurrence of thin beds of limestone.! . 



Pursuing my investigations down the Ohio from this place, I 

 found the group which is designated sub-carboniferous, suc- 

 ceeded by a thick and persistent mass of limestone, presenting 



* The thickness given was furnished me from the smreys of road engineers, in a 

 Letter from Dr. Clapp, of Sept. 2nd, 1S42. 



1 1 find, on reference to the Report of Dr. Owen on the Geology of Indiana, that he 

 has denominated the rocks here described, as well as the succeeding limestone, " Sub- 

 carboniferous." This fact was overlooked till the section was in the hands of the engra- 

 ver and the paper entirely written. The limestone following is denominated in its differ- 

 ent parts by Dr. Owen and Dr. Troost, as Oolitic, Pentremital, and Archimedes lime- 

 stone. After taking all possible means to obtain a copy of Dr. Owen's Report upon the 

 Lead region, I have been unsuccessful, and this must be my apology for appearing igno- 

 rant of what has been done in that region, except of the general fact of the identification 

 of the Lead-bearmg rock with the Cliff limestone of Ohio and Indiana. 



19 



