Average total organic carbon (TOC) content in the Barnett Shale is about 4% and TOC is as high as 12% in samples from outcrops along the Llano uplift on the south flank of the Fort Worth Basin. It has geochemical characteristics similar to other Devonian-Mississippian black shales found elsewhere in the US (e.g., Woodford, Bakken, New Albany, and Chattanooga Formations). These black shales all contain oil-prone organic matter (Type II kerogen) based on hydrogen indices above 350 milligrams of hydrocarbons per gram of TOC and generate a similar type of high quality oil (low sulfur, >30 API gravity). Although kerogen cracking decomposition is a source of oil and gas from the Barnett Shale, the principal source of gas in the Newark East Field is from cracking of oil and bitumen.