Petrified Forest (IMAGE) Arizona State University Caption The USArray, which is part of the EarthScope experiment, is a 15-year program to place a dense network of permanent and portable seismographs across the US, with the Petrified Forest as one of the many locations. Credit Photo courtesy of Steve Semken. Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.