Yellowstone and the Grand Tetons

Morning Glory Pool originally had a vivid turquois color, caused by bacteria living in the water. This photo from August 1991 shows it as a vivid blue. More recent photos show the pool as green, caused by intentional and unintentional vandalism as visitors have thrown things into the pool, and the park service has signs posted calling it a "Faded Glory."

The literal high-point of a trans-continental trip in 1991: spending a few days over a mile in the air in Wyoming, in the massive Yellowstone ecosystem.