216 
GEOLOGY OF THE THIRD DISTRICT. 
In the instance of contortion given of the Trenton limestone, we had an example where the 
force was within the mass ; here, one of lateral pressure upon very yielding materials, being 
probably in a softer state than the contiguous undisturbed parts. These instances, so far, 
afford us the only two known causes of contortion, plication, etc. of rocks ; and may explain 
all the known cases of disturbance of like appearance, without resorting in any wise to forces 
acting from below. In the rising and falling of great masses — and continents illustrate 
such movements — a lateral pressure would result, forcing whatever soft or yielding mate¬ 
rials were subjected to its power, to act upon themselves; hence plications, contortions and 
curvatures would be produced, like those of the clay beds of Black river, were the layers thin 
and yielding to pressure. The same results would ensue, were a part of a mass subjected to 
crystallization, having insufficient space for expansion, or if unequally resisted by associates. 
75 . 
Section extending at a right angle from Black river, showing that the materials of which the hill is composed came from the 
direction of the river. 
No. 1. Apparently a mass of yellow sand, forming the bank of the river. 
2 .) 
4. > Rolled stones of primary rock, limestone of Black river, and Trenton rock and sand with loam in No. 6. 
6 .) 
g' | Sand same as No. 1. 
At the point where the feeder diverges from the river, there are alternations of rolled stones 
of the largest size, and sand, rising apparently upon a mass of sand, the top of which is 
about sixty feet above the river. The deposit of rolled stones and sand dip from the river at 
a considerable angle, showing that the direction whence they came was from the part now 
occupied by the valley or river depression on that side, the former showing no rise for a long 
distance from the river. The alluvial hill rises one hundred or more feet in perpendicular 
height above the river. 
The plain of Boonville, south of the village for some miles, and along the whole course of 
the river to the mouth of the feeder, shows hills of alluvial; rising about the same height as 
along Black river, but more generally placed upon the Trenton limestone, which forms the 
surface rock of that part of the country. 
