Jewel Cave
National Monument
South Dakota, USA
Exploring in the vicinity of Mount Rushmore, I found the
quite lovely Jewel Cave, whose color for images was green.
Caves are always fun.  This looks like some kind
of abstract art.
Perhaps the discoverers of Jewel Cave thought they
had found an emerald mine.  Wrong.  For a different
cave experience in the US, consider clicking on New
Mexico's
Carlsbad Caverns.   
If you have a high speed internet connection, watch this
Intrepid Berkeley Explorer free video of National Parks and
Monuments in South Dakota, Wyoming, Utah & Arizona by
clicking on:
Dances With National Parks