What is Karst?

Karst is rock that has been carved by water flowing through it.  Usually it is limestone but it can also be other types of rock, like marble.  Because of the way that the rock is carved (with big spaces that allow for water to continue flowing through it), much of the water that we drink in the U.S. comes from karst aquifers (underground water supplies stored in the spaces in the rock).  The map below shows where Karst comes from (click on image to enlarge):

Other Resources to learn about Karst: