The geological structure of that portion of southern Missouri which lies to the westward of the Archean rocks near the Mississippi River is peculiarly suitable for the development of caverns. The Ozark uplift produced far-reaching undulations, and there seem to have been no violent disturbances which would result in extensive faults, considerable displacements, or a pronounced inclination of the strata. Jointing and pressure cleavage, however, gave rise to innumerable crevices in the limestone, through which percolating surface water found its way into all parts of the formations.