The purpose of this article is to explain the depositional environment, petrology, mineralogy, structure, exploration, technology, methods of extraction and processing, as well as petroleum applications and economics in the Greater Green River Basin. This paper will focus primarily on the oil shale within the basin, but will also touch on some of the more conventional oil and gas reservoirs. According to Crawford and Killen (2010), oil shale is defined as “a sedimentary rock embedded with organic material called kerogen… and has not been subjected to the necessary heat, pressure, and/or depth for the right amount of time to form crude oil". Oil shale is typically found in silica- and carbonate-based rocks that usually do not exceed 900 meters in depth and can range from very thin beds at the surface to beds hundreds of meters thick that occur much deeper (Ogunsola al. 2010). Shale is considered a good cap rock for hydrocarbons because it is a fine-grained sedimentary rock made up of clay and silt particles that have been lithified into thin but impervious rocks. The fact that they are impervious is what makes them an excellent cap rock (Leffler et al. 2011). The Greater Green River Basin contains some of the largest oil shale deposits in the world, primarily in the Green River Formation. The Greater Green River Basin covers parts of Colorado, Utah, and Wyoming. This basin is suspected to contain a significant amount of oil, between 1.5 and 1.8 trillion barrels, held exclusively in the Green River formation. The Greater Green River Basin is composed of four depositional basins that include the Piceance, Unita, Washakie, and Green River basins. The Green River Basin contains approximately 250 billion barrels, while the Piceance Basin is... center of map... Technical Guide. Tulsa, OK: PennWell, 2003. Print.• Klein, Cornelis, Barbara Dutrow, James Dwight Dana, and Cornelis Klein. The 23rd edition of the Handbook of Mineral Sciences: (by James D. Dana). Hoboken, NJ: J. Wiley, 2008. Print.• Pedersen, Todd F., and S. E. Calvert. “Anoxia vs Productivity: What Controls the Formation of Organic-Rich Sediments and Sedimentary Rock?” Bulletin of the American Association of Petroleum Geologists (1990): n. page Network. April 14, 2014.• Roehler, Henry W. Introduction to the geology, physiography, and history of investigations of the Greater Green River Basin. Washington: USGPO, 1992. Print.• Ryan, Robert C., Thomas D. Fowler, Gary L. Beer, and Vijay Nair. “Shell's In Situ Conversion Process: From Laboratory to Field Pilot Projects.” Oil shale: a solution to the liquid fuel dilemma. Washington, DC: American Chemical Society, 2010. Page No. Press.