Photo Credits

Far left photo - Cliffs of the Green River Formation, Parachute,
Colorado. Photo by J. Boak, 2006

Second from left - Oil Shale Area near Parachute, Colorado
Creatas Royalty Free Photograph

Second from right - Shell Freeze Wall Test Site, 2006  
Credit to Harold Vinegar, Shell's In-Situ Conversion Process,
Proceedings, 26th Oil Shale Symposium, CD Revision 1,
Colorado Energy Research Institute Document 2007-4,
Colorado School of Mines, 2007. 

Far right photo - Green River formation
Copyright © Bruce Molnia, Terra Photographics