More than 1000 roofless solution cavities, filled with clay, shale, sandstone, coal, hematite, pyrites, galena, sphalerite, barite, and dolomitic debris, lie on the northern and western slopes of the Ozark dome. More than a score of geologists have proposed seven different concepts regarding the genesis of some of these cavities and their fillings. The favored three concepts are: (1) original surface sink holes; (2) collapsed caves; and, (3) gradual subsidence of overlying rocks keeping pace with solutional removal, under saturated conditions, of subjacent calcareous rock. The others are: (4) deposition of fills in unquiet seas; (5) dropping of fill material at intersection of faults; (6) collapse of superjacent filled caves into subjacent empty ones; and (7) localized upward thrust. This paper intends to show that the filled sinks and the circles constitute two different categories of solution cavities. The circles, properly defined, are collapsed caves but only concept (3) can explain the compressional deformations which the fills and cavity walls of the sinks exhibit.