Rain falls on the Ozark Hills, seeps into the soil and into vertical cracks in the underlying rock, picks up a horizontal joint in a rock formation, erodes a conduit, rises, and emerges as a spring.
Big Spring, the largest in Missouri, spews 470 cubic feet of water per second. It draws its water from sites over 40 miles away. Its spring brook carries it to the Current River. Think of it as a tributary of the Current.
Native Americans named it Blue Spring because it reflects the deep blue of the sky. Actually, the blue is dissolved limestone, eroded from conduits that reach under the Current River watershed and into the Black River watershed.
Water spills into sinkholes in a plain north of Alley Spring and runs through underground conduits to the spring, which stopped running one day. When it started again, it disgorged muddy water. It seems one of those sinkholes collasped and clogged a conduit. The spring did not clear for days.
Roaring River Spring rises from a source that draws its water from Mississippian rock formations. A second spring that falls into the pool rises high above the first and carved a deep hollow in the Jefferson City formation, a much older rock.