The role of organic carbon in hydrocarbon-bearing deltaic environments is dependent upon taphonomic processes affecting resident biotic communities. Crude oils recovered from the Mahakam Delta, Indonesia, have been shown to be derived exclusively from type III kerogens (humic organic material of terrestrial and woody origin). The project is centered on the identification and characterization of phytotaphonomic processes responsible for the accumulation and alteration of terrestrial plant parts with the Holocene and Neogene depositional environments in the Mahakam Delta. The sampling program will involve recovery of plant macrodetritus from vibracores, box cores, and detrital peat beach ridges. A reconnaissance vegetational survey of biotic communities will be undertaken to identify the principal contributors of canopy parts to these deltaic sediments. The recognition of the taphonomic processes involved will contribute to our assessment of the principal sites and potential preservational modes of macrodetritus in plant- bearing deltaic regimes. Results from the project will provide significant insight into the role played by tropical lowland vegetation in the genesis of recoverable Tertiary hydrocarbons.