1880.] 375 [Crosby. 
sometimes nearly cylindrical or prismatic, and usually presents trans- 
verse sections of similar shape in all parts of its length. 
As already intimated, the distortion does not stop at the incipient 
stage, as in the Boston conglomerate, but a large proportion of the 
pebbles have taken on forms which are absolutely inconceivable, as 
the result of any known mode of attrition. Pebbles six to ten 
inches long, and less than one inch in diameter are not at all uncom- 
mon; and I have measured those which were more than a foot long, 
and less than one and a half inches in diameter; while there are 
comparatively few in which the ratio of the length to the diameter 
falls below 4:1. Elongation, however, is not the only evidence of 
distortion. As arule the ends of the pebbles are not rounded, but they 
more often taper gradually to a sharp thin point, and I have observed 
cases where the surfaces toward the extremities were actually 
concave, like the edge of a razor, giving a termination of excep- 
tional sharpness, and one that could not possibly be developed by 
surf action. In other cases the edges or extremities of the pebbles 
become blended with the cement, or with the substance of adjacent 
pebbles, so that their outlines are lost. 
The pebbles are all elongated in the same direction, and this is 
invariably parallel with the strike of the beds. The structure is 
such that any vertical surface cutting across the strike affords the 
aspect of a normal conglomerate, the pebbles exhibiting no sensible 
deformation; while on any surface parallel with the strike, whether 
in the plane of the beds or cutting them at any angele, there is 
nothing to suggest the real nature of the rock; for, viewed in this 
manner, it shows no trace of pebbles, but only a beautiful schistosity, 
resulting, apparently, from the interlacing of thin lenticular layers of 
various colors and diverse composition ; although, as just stated, on 
the cross-section these seeming layers are seen to be rods. 
This curious structure clearly admits of but qne explanation, viz.: 
the horizontal pressure which folded the strata, and operated ina 
direction at right angles to the strike, has been accompanied by a 
sensibly equal vertically acting force or pressure, and under the 
combined influence of these, the beds and likewise their constituent 
pebbles, have been squeezed out in the direction of least resistance, 
or parallel with the strike. 
Occasionally one may see a pebble of epidote or other re- 
fractory material which has successfully resisted the drawing 
_ or squeezing out process, and is now enveloped by the litho- 
