This giant Geode is at the Museum of Nature History in Houston, Texas.  A geoda is formed when liquid crystal solution seeps into an open area in rock then over time this highly saturated solution of a mineral will form crystal in the void in the rock layer.  Then over a long period of time the surrounding rock will be weathered by wind, water, and ice.  When more weather resistant geode will finally be exposed on the surface of the ground.  As you can see geodes take on varied and interesting shapes.  When I visited a store outside the Petrified Forest National Park, there was a geode that had three large legs.  Someone had cut the top off the geode exposing beautiful blue crystals which lined the entire inside of the geode.  A piece of furniture glass was attached on top.  The price tag of this 5 and 3 foot geode table was a mere seven thousand dollars!

The interesting point is that part of the southwest which are now hot and dry were more like swamps with many trees and prehistoric animals.  Scientists now say that geologic evident shows that the large area was uplifted by 3000 to 4000 vertical feet over a long time.  Thus this area saw climate change with a change in plant and animal life.  In a ancient indian village close by, it is known that the area once supported farming.  Now the area is desert-like and a near by river is dried up most of the year.