The requisites for hydrocarbon entrapment (source rock, reservoir rock, and sealed trap) are present in the Marathon fold-thrust belt. The Pennsylvanian and Wolfcampian shales in the Marathon area probably yielded hydrocarbons during diagenesis and porosity has been observed in several potential reservoir strata. Thrust and reverse faults are among the trapping mechanisms that have been observed and evidence of stratigraphic porosity and lithology pinch-outs and tectonic wedge-outs has been reported. A predictive model of the sub-surface occurrences of such traps is based on the premise that compression from the Permo-Pennsylvanian collision of North America with South America created a back-arc fold-thrust belt at Marathon. This model identifies some of the components of the collision orogene and it describes some of the geologic processes that created those components.