Page:The Geologist, volume 5.djvu/49

Rh cause of a cavern must have been a fracture in the limestone rock, consequent on the upheaval of the strata, and that water then finding access to the crack, would wear it out to its present dimensions.

Fractures in this case would most probably take place when the "Red Vein" was formed, which is only between two hundred and three hundred yards distant from the cave, and crosses the ravine nearly at right-angles. This vein, which contains lead-ore, iron-stone, etc., is a wide one, requiring a wide fissure, and the force necessary to produce such a fissure would be sufficient to cause rents and small dislocations in the rocks at considerable distances. Besides this there are two other veins crossing the ravine at lesser distances from the cave, and these would still further increase the probability of an original fissure.

The cave must be very old if we suppose it to have been formed by the water running down the ravine when on a level with its mouth or opening, seeing that the watercourse is now worn down ten or twelve feet below the cave's bottom. Again, if we suppose it to have been excavated by the attrition of the waves of the sea during some remote period, when the waters of the ocean stood on a level with the cave, it must still have a very ancieut Origin, for the Cave is situated upwards of thirty miles from the Sea, and Upwards of eight hundred feet above its present level. This locality must have been submerged during the glacial period, as we have evidence of by the deposits of boulder clay; and if the sea on receding should have remained on a level with the limestone for a great length of time, the result would have been the wearing down of the rock, or the hollowing out of crevices and caves in the exposed strata.

In a certain place of the cave-flooring, the workmen recently came upon a large sheet of stalagmite of varying thickness, but averaging about four inches. This calcareous incrustation has been formed by the ceaseless dropping of water holding lime in solution, from the roof of the cave. On removing this crust and a small portion of fine