Figure 18. Events chart summarizing the major elements of the Upper Jurassic-Cretaceous-Tertiary composite total petroleum system of the Gulf Basin. Modified from Condon and Dyman (2006). The critical moment is defined as the point in time that best represents the generation, migration, and accumulation of most of the hydrocarbons in the Upper Jurassic-Cretaceous-Tertiary Composite total petroleum system. As relates to the Claiborne Group, this is in Upper Claiborne time when the sand-rich Yegua and Cockfield reservoirs were deposited. Abbreviations: E = Early, M = Middle, L = Late, TR = Triassic, Paleo. = Paleocene, Olig. = Oligocene, Po = Pliocene, P = Pleistocene, Quat. = Quaternary.