NIAGARA GROUP. 
95 
The drawing fig. 1, is from a specimen, and of the natural size. The curving of the lamina; 
is precisely as in the quarry at Niagara Falls, and intermediate between that and those of 
Lockport, where they are much smaller than in this figure. In a few instances at Rochester, 
some thin strata exhibit the appearance represented in figure 2, where the rock, after being 
partially hardened, was broken up, and again cemented. The cementing matter is usually 
crystalline. These appearances are more common in the central portions of the rock, and 
are not seen in the higher strata. 
The lower and middle portions of this limestone, in addition to the regular seams or divi¬ 
sional planes, often present a kind of undulating seam or suture, the projecting portions of one 
layer closing into corresponding depressions in the other. These, from being scarcely visible, 
become of considerable magnitude, and the projecting portions on either side an inch or more, 
and even five or six inches in length. These have been compared by Mr. Vanuxem* to the 
sutures of the skull, which they often resemble. When separated, the surfaces present a 
parallel fibrous or striated appearance, and are frequently covered with a film of carbonaceous 
matter. These appearances, which occur not only in this rock, but in the water lime and 
some of the higher rocks, were termed by Prof. Eaton, Lignilites, from their resemblance to 
woody fibre. They are not always at the junction of two layers, or as forming a division, 
but frequently penetrate the solid stratum, and are separable, appearing like a wooden pin 
driven into the mass. Again they divide the rock into columnar blocks of variable dimensions. 
The illustration No. 32, is from a specimen where the striated surface is eight inches long, 
and has separated a portion of the rock into an irregular column. 
i 
