Petrified Forest National Park, Arizona
Agate Bridge spans 110 feet and was once a towering tree. Over time the tree died, was carried downstream where it was quickly buried in sediment and over time silica began to replace the tree, eventually becoming the log it is today. In 1911, visitors and conservationists were afraid that the bridge would collapse, and they reinforced the former tree with support. It sure is amazing and I am so glad we went and saw it while on a recent trip.
Taken with a Canon 50D