Sinkhole

A sinkhole was a hollow area in the ground. 
Sinkholes were a feature of Karst topography. The duck blind on Mintaka III was surrounded by sinkholes, among other features. () 
Certain spatial phenomena were also described as sinkholes. ()
==See also==
* Spatial sinkhole
* Subspace sinkhole
==External link==
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Category:Landforms