A eoalified wood fragment and thin coal beds from the type locality of the Itaquaquecetuba Formation (Cenozoic, São Paulo Basin) were submitted to conventional organic petrographic studies. Under reflected light, it was possible to observe the occurrence of gelification processes in the samples that transformed the woody material into huminite (a vitrinite precursor). The huminite mean reflectance is around 0.15% Ro, which characterizes the material as peat on the rank of coal. These observations lead to the conclusion that the beds containing the wood fragments have never been buried to depths significantly greater than that at which they are now found
