KARST (CONTINUED)

A region with many sinkholes is called a KARST region, and as you might expect, the caves beneath the ground affect surface drainage dramatically.  In fact, the word "karst" comes from a Croatian word that means "desert" because the karst area of Croatia has virtually no streams.  The climate is abundantly wet but all the water goes quickly underground after a rain!

The first picture shows the Little Alapaha River, a DISAPPEARING STREAM near Jennings, FL.  The stream flows from north to south, entering a long, narrow sinkhole near the north end of the map.  It crosses a second hatched contour just east of the "33" and appears to end a short distance to the south.  In fact, it enters a cave at this point.  Note the numerous other sinkholes in the vicinity of the Little Alapaha.  Several other streams and parts of streams obviously disappear nearby.  The Alapaha River proper, about a mile to the west, gradually loses water into obvious sinks as well as its highly permeable bed and is often completely devoid of surface water.

A few miles to the south lies the Suwannee River.  The map below shows the mouth of the Alapaha as a permanent stream, but this is a bit misleading.  During much of the summer and fall there is little or no surface discharge of the Alapaha at its mouth -- it is bone dry.  The small tributary labeled "Alapaha Rise" is a much more reliable tributary to the Suwannee.  You can see from the map it lies in a deep, steep-sided valley.  It is, in fact, a blackwater spring.  Its name reflects the belief that this is where all the Alapaha's water goes when the river is dry, and that is certainly partially true.  There is probably also water from the Little Alapaha and the several other disappearing streams to the north.

The valley of Alapaha Rise is almost certainly a collapsed cave.  The spring itself comes out of cavernous porosity, and I assume that someone has at least attempted to SCUBA dive in it, as they have in most of the regional springs.  Such a valley is called a SOLUTION VALLEY.  One hypothesis is that the Suwannee through this stretch (and along much of its course, in fact) is in a solution valley.

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