The region of Mineral Springs in Eastern New York consists of a long, shallow and crescent-shaped valley, extending northeast from Ballston, its western horn, to Quaker Springs, its eastern extremity. The entire valley abounds in mineral fountains of more or less merit, and in the central portion bubble up the Waters of Healing, which have given to SARATOGA its world-wide celebrity. Professor CHANDLER, of the Columbia School of Mines, thus describes the Geology of the County. "Beginning with the uppermost, the rocks of Saratoga county are: 1. The Hudson river and Utica shales and slates. 2. The Trenton limestone. 3. The calciferous sand rock, which is a silicious limestone. 4. The Potsdam sand stone; and 5. The Laurentian formation of gneiss and granite, of unknown thickness. "The northern half of the county is occupied by the elevated ranges of Laurentian rocks; flanking these occur the Potsdam, Calciferous and Trenton beds, which appear in succession in parallel bands through the central part of the county. These are covered in the southern half of the county by the Utica and Hudson river slates and shales. [Illustration: GEOLOGICAL SECTION AT SARATOGA SPRINGS.] "The most remarkable feature is, however, the break, or vertical fissure, which occurs in the Saratoga valley, which you see indicated in the cut. Notice, especially, the fact that the strata on one side of the fissure have been elevated above their original position, so that the Potsdam sandstone on the left meets the edges of the calciferous sand rock, and even the Trenton limestone on the right. It is in the line of this fissure, or _fault_, in the towns of Saratoga and Ballston that the springs occur. "The Laurentian rocks, consisting of highly crystalline gneiss, granite and syenite, are almost impervious, while the overlying Potsdam sandstone is very porous, and capable of holding large quantities of water. In this rock the mineral springs of Saratoga probably have their origin. The surface waters of the Laurentian hills, flowing down over the exposed edges of the Potsdam beds, penetrate the porous sandstones, become saturated with mineral matter, partly derived, perhaps, from the limestones above, and are forced to the surface at a lower level, by hydrostatic pressure. The valley in which the springs all occur indicates the line of a fault or fracture in the rocky crust, the strata on the west side of which are hundreds of feet above the corresponding strata on the east.