OF DENISON UNIVERSITY. 
13 
rock is the common freestone used so extensively for foundation work 
and building purposes. In Plate A can be seen the face of the solid . 
rock which is worked, and a considerable portion of the broken ma- 
terial above it. Nejr the center of the illustration will be seen a large 
block of the harder portion of the rock, which has its corner broken 
by quite a number of curved fracture lines nearly parallel to each 
other and making almost a perfect truncation of the corner. These 
broken portions have slipped quite a little on the block in a downward 
direction, as seen by the fine lamination lines, thus indicating that the 
fracturing force was from above in a vertical line or but varying 
slightly from the vertical, and that it was not lateral, else the motion 
would have been in the other direction. Plate B represents a view of 
the rocks above the quarried rock in the same exposure, but on a little 
larger scale. Here it can be seen the rocks are fractured into all 
kinds of forms, having all sorts of curved and irregular faces, and it 
is impossible to trace any continuous jointing or stratification planes. 
However, in the individual fragments it is evident that the planes of 
stratification have been functional in determining form. On the top 
of this hill was found a number of erratics, and on the south side of the 
hill is a large deposit or glacial drift. 
The next quarry illustrated, is located about one and a half miles 
south of Newark, and was chosen because it was about on an equal 
elevation with the first, and the exposure can be identified as 
being of exactly the same geological horizon, by a thin layer of 
coarse grained sandstone which is present in both. If, however, we 
study the rocks in this quarry, as will be seen in Plates C and D, 
which are taken from different parts of the same exposure, we will find 
that they are broken largely in but two directions, one along the 
planes of stratification, which can be followed through the whole 
quarry, no matter how near we approach the surface, the other almost 
at right angles to the first, vertical or nearly so, and corresponding 
in direction to the joint planes of the underlying harder rock. It will 
be seen also in Plate D especially, that no matter how close the rocks 
may come to the surface at the side of the hill there is no apparent 
breaking over in concoidal fractures. We also notice that the disinteg- 
ration depends almost entirely upon the varying composition of the 
individual strata. No erratics were found^on^top of this hill, al- 
though they^were quite abundant in the proximate valley, and drift 
material is also abundant at, the bases of the neighboring hills, Many 
