Isothermal and nonisothermal pyrolysis experiments have been conducted on Asphalt Ridge tar sand. Oil produced from the isothermal experiments has a molecular weight of approximately 250 and has a hydrogen to carbon ratio between 1.7 and 1.9. Product oil composition varies slightly with reaction time. Results of thin layer chromatographic separation of the residual bitumen show that the concentrations of saturates and aromatics in this bitumen decrease rapidly with increasing reaction time, while the concentrations of aromatics and polars in this bitumen increase. Polars and polynuclear aromatics are the dominant species in this bitumen. Nonisothermal data have been analyzed using a distributed activation energy technique. These tests show a distinct bimodal weight loss curve. The low temperature weight loss peak has a maximum about 275/sup 0/C (527/sup 0/F) and a first order apparent activation energy below 10 kcal/mol. The high temperature peak has a maximum above 400/sup 0/C (752/sup 0/F) and an apparent activation energy of about 60 kcal/mol. 12 refs., 11 figs., 8 tabs.