Bulletin of the National Speleological Society - ISSN 0146-9517
Volume 26 Number 3: 83-114 - July 1964
A publication of the National Speleological Society
Artesian Origin of Fissure
Caves in Missouri
Langford G. Brod, Jr.
Many pits and small caves with similar but unusual characteristics exist in four eastern Missouri counties. These caves and pits exhibit pronounced joint control and have been termed fissure caves. The caves all lie in a narrow northwest-trending belt about five miles wide and 40 miles long, which is approximately coincident with the Rockwoods anticlinal fold belt. Most of the caves occur in the Plattin limestone of Ordovician age. The caves are solutional in origin and are thought to have developed under artesian conditions. In order to determine the depth of solution, the altitude of river terraces and pre-Pleistocene erosion surfaces were studied, permitting a partial reconstruction of pre-Pleistocene topography. The primary impetus in speleogenesis came from slight regional tilting in the area of the fissure caves, related to uplift of the Ozark dome. Subsurface water drained off the dome through a dipping sandstone aquifer wich eventually carried it deep underground. The water was again brought near to the surface in the eroded Rockwoods anticlinal fold belt, and emerged along its flanks in a series of resurgences. The artesian water ascended from the sandstone through the overlying limestone along joints, and solution of the walls of these joints produced the fissure caves. With subsequent planation of the surface, circulation virtually ceased, and the caves filed with red clay. During the Pleistocene Epoch the caves were drained and cleared of most of their fill. Entrances formed when upper sections of the chambers were intersected by recent erosion of the surface.
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