June 18. Karst topography

Karst topography develops in areas underlain by soluble carbonate rocks like limestone. In some areas, the rock is mostly dissolved in the subsurface, forming caves and sinkholes, common in Indiana and Kentucky and Florida and many other places around the world. 

Karst topography in China

In parts of Puerto Rico, extremely high rainfall, more than 65 inches a year, helped dissolve most of the limestone leaving behind the parts that were slightly more resistant. The residual hills are called haystacks or pepino hills and sometimes they can reach mountainous proportions, hundreds of feet high and often with nearly vertical flanks. China also has some amazing karst mountains.

The name karst comes from the Karst Plateau in the Dinaric Alps of Slovenia, whose name comes from a German word of probable Slavic origin meaning “a bleak, waterless place.” That’s something of an ironic name since it was an abundance of water that caused the topography. But in many karst areas, much of the water flows underground because of the subterranean caves and even rivers. Lost River, in southern Indiana, is lost because it flows on the surface for a distance, but then plunges underground for several miles. Because of the subterranean drainage, the surface may have few or no lakes as well, so karst plains can indeed seem waterless. 

—Richard I. Gibson

Photo of karst topography in China by chensiyuan via Wikipedia, under Creative Commons license.