Sinkholes, Caves, & Cones of Depression

a Sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer.

a Cave is a cavern in the ground. These can hold water, minerals, animals, etc. But most importantly, these can hold water from rivers, & streams.

a Cone of Depression occurs in an aquifer while the groundwater gets pumped from a well to the surface.