THE DOLINE
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ranean streams drained and accumulated from the
1 limestone surface of the Karst, operating along lines of stratification or fissure, and proceeding, by a chemical process of corrosion and a mechanical process of erosion, to form these underground caverns and grottos. The lines of stratification or of fissure are not, however, perfectly even and regular. They have been bent and broken by lateral pressure, perhaps volcanic, at some infinitely remote period. These bends and breaks along the course of the underground rivers give rise to headlands which produce eddies where the direct flow of the water is hindered and impeded, and thus circular pools are formed, as would happen in the case of an above-ground river; but being underground these eddies form grottos and caves, which, when their roofs eventually fall in, become the doline of the Karst. The presence of stalagmites on the floors of the doline prove that they were at one time roofed in. When the roof has fallen in, a lateral process of detrition, under the action of the weather and surface corrosion, begins, and, as the side walls of contiguous doline break into I one another, we get the blind valleys and elliptical cauldrons so characteristic of the whole geological structure, which is thus due to a process of corrosion,