Figure 4. A map view of the isotopic data shown in Figure 3 defines the two main methane anomalies, and suggests that the isotope values in the forty-one monitor wells are controlled by proximity to source. The two most thermally mature, and uniform isotope anomalies within the gravel aquifer at depth provide confirmation of the two major soil gas anomalies. Surface macroseeps, found by the soil gas survey have been collected and analyzed that match exactly to the compositions of the gases found in the aquifer.