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EXTRACTS FROM THE JOURNALS, &c. 
AGRICULTURAL GEOLOGY. . 
BY J. HALL. 
Niagara Group — Geodiferous ime Rock and Calciferous 
Slate, of Eaton. Lockport Limestone, and Rochester Shale, of 
the Annual Reports of the Fourth District. 
This group consists of two distinct members, a shale and lime- 
stone, which, possessing many features in common, are recogniz- 
ed as the products of one period; during which, however, there 
was an important change in the lithological products, and a less 
one in the organic forms. The shale continues a very uniform de- 
posit throughout the whole extent of the district, while the lime- 
stone, from a thin, dark-colored concretionary mass, becomes an 
extensive and conspicuous rock, constantly increasing in thickness 
in a westerly direction, even far beyond the limits of the State. 
The Cataract of Niagara is produced by the passage of the riv- 
er over this lime stone and shale; and from being a well known 
and extremely interesting point, as well as exhibiting the great- 
est natural development of these rocks within the limits of the 
State, this name is adopted for its designation. 
The members of this group are : 1. Argillaceous, or (in ma- 
ny localities) argillo-calcareous shale. 2. Limestone, presenting 
several different varieties. 
Niagara Shale. 
The lower part of the Niagara group exhibits a great develop- 
ment of dark, bluish shale, which on exposure gradually changes 
to grey or ashen color, and forms a bluish or greyish marly clay. 
In this state, it is undistinguishable from the ordinary clays; and 
its outcropping edges, where long weathered, are often consider- 
ed as claybeds. This character is well exhibited at Lockport, on 
the northern slope of the terrace where the canal and railroad have 
been excavated; and also at numerous localities in Wayne and 
Monroe counties. The depth of tint in the clay differs according 
to degree of exposure, the outer portions becoming of the usual 
yellowish-brown color of the ordinary soils. 
