Mammoths and the Sinking Hole

The cavern was so far underground that the rock on top of it, being so heavy, collapsed inward. This formed a gaping, 120 by 150 foot sink hole in the ground. The sink hole filled with water and eventually overflowed,. spilling out over the sides and on to the surrounding ground. To an unsuspecting mammoth, this looked like a pretty good place to get a drink. But even for these appa michael phelps, like mammoths, the sink hole walls were just too steep and too slick. Once they got in, they could never climb back out.