How are the caves formed at Rock City?
Although often called Wind Caves, they are only indirectly due to the wind. During the rainy season, water seeps into the rocks. The water is a very weak acid and slowly dissolves the cement that had been holding the sand grains together. The hot dry days of summer would draw the water to the surface of the rock where it evaporated and left behind the cement it had dissolved from deeper in the rock. After centuries of wet winters and dry summers, the inside of the rock had only a little cement, while the outside had a hard crust of sand grains tightly cemented. As wind and rain continued to beat on the faces of the rocks, holes developed in the crust. This exposed the loosely cemented grains underneath, which erode much faster than the surface, so that holes enlarged into little caves behind the hard crust. Very little of the hard crust remains on the surface of these rocks today. This text was reproduced from “Geology of Mt.
