How are springs formed?
Springs may be formed in any sort of rock. Small ones are found many places. In Missouri, the largest springs are formed in limestone and dolomite (a magnesium bearing limestone) in the karst topography of the Ozarks. Both dolomite and limestone fracture relatively easily. When weak carbonic acid (formed by rainwater percolating through organic matter in the soil) enters these fractures it dissolves bedrock. When it reaches a horizontal crack., or a layer of non-dissolving rock such as sandstone or shale, it begins to cut sideways, forming an underground stream. As the process continues, the water hollows out more rock, eventually admitting an airspace, at which point the spring stream can be considered a cave. This process is supposed to take tens to hundreds of thousands of years to complete. The age of a spring or cave is difficult to estimate due to the variables of rock composition and water volume doing the work. Also, because a catastrophic event may cause a rock collapse in min
