Page:Popular Science Monthly Volume 19.djvu/36

26 Trenton limestone; and, No. 5, the Utica or black slate; the fault, or break-off, is indicated by the heavy black vertical line, in immediate proximity to which the village of Saratoga Springs is situated. For the reason that the black slate has been entirely eroded from that portion of the village immediately west of the fault, and the Trenton limestone nearly so, none of the former and but a thin stratum of the latter formation is represented on the accompanying chart. You will observe that both the dislocation and upheaval of these various strata are strongly marked at the fault, for, while that portion lying to the east remains in situ, that to the west is tilted up to such an extent that the dip of some of the strata is as great as twenty degrees. You will also notice that the Laurentian rock on the west side of the fault, occupying the position designated as No. 1 on the cut, as well as the superimposed strata, viz., Nos. 2, 3, and 4, are not in perfect opposition with formations of like character on the east side, the Potsdam sandstone lying opposite to the Trenton limestone, the calciferous sand-rock lying in conjunction with the black slate, while the Trenton limestone on the west occupies a position above the black slate on the east. The consideration of this phenomenon naturally suggests an explanation, but so far as is known there is but one theory relative to the subject, it being universally conceded that the force that produced this disruption was due to volcanic agency.

At distances varying from two to twelve miles in a westerly direction ranges of hills and mountains are encountered, presenting altitudes several hundred feet above this village. In addition to the enormous area of water-shed that these elevated regions afford, they possess many ponds and lakes, some of which are of no insignificant size. The surface-streams that drain this section flow toward the east, and, as the various strata dip in the same direction, the tendency of the subterranean drainage must be toward the same point of the compass.

The advocates of the first of the theories regarding the origin of the mineral springs of Saratoga, recognizing the disintegrating and solvent action of the water under its various forms of rain, snow, and ice, claim that they are produced by the process of displacement or percolation, holding that, when water falls upon the elevated regions just described, a portion of it gradually permeates the soil and the various strata of the underlying rocks, dissolving and carrying with it in its downward flow the various constituents of which the rocks are composed, and that these are decomposed by their reaction on each other, and new compounds are formed with the evolution of carbonic-acid gas, that this is dissolved by the water, which becomes highly impregnated with it, increasing its solvent properties to a great extent, enabling it to accumulate basic matter in its flow, which continues downward and eastward, until the fault is reached, where an opportunity is afforded for it to escape from the rocks and rise to the