190 
GEOLOGY OF THE SECOND DISTRICT. 
a fine natural section of the strata : they have a dip first to the south, which changes to the 
west and northwest, but it is only slight, and the lowest strata that can be observed are only 
a few rods below the bridge. The above view of these falls was taken from the north side, 
about twenty rods below the bridge, or at that point where they are the most distinct when 
seen beneath it. 
It will be a repetition of what has already been said, that most if not all of our falls are 
produced by uplifts of the rock; and I make the repetition merely to call the attention of 
observers more to this fact, as it brings out fully and clearly the truth of the assertion that 
these phenomena are principally due to geological causes. We are not aware how great and 
how extensive have been the operations of certain agents in the production of all such changes 
upon the earth, and how much they diversify the physical features of our landscapes. In 
order, therefore, to understand physical geogi'aphy, the elements of geology, at least, become 
essential; as without them, we are deficient in some important items of knowledge. 
The slight break in the limestone at Glen’s falls is an interesting fact; for, from examina¬ 
tion, it seems to be due rather to a wave communicated to the crust, than to a more direct 
application of force beneath ; an oscillation, or wave which was communicated at the time the 
great fracture of the Hudson river slates took place. Some facts confirmatory of this view 
will be related when I speak of the limestone of Essex county. 
