Figure 4. Nejo well log (left), with cored intervals (defined by pink lines), of Frio Marino Formation. Dominant coarsening-up cycles may be observed on the GR and resistivity log curves. Some of the most important core samples are presented on the right. A--Fine-grained sandstone bed, 10 cm thick, with rip-up mudstone clast (1) and evidence on top of wave reworking (2), interbedded with black shale, and silty, bioturbated with Ophiomorpha (3). B-- Parallel-laminated fine-grained sandstone (4) with oil impregnation (thickness=15 cm). C--Low-angle, laminated fine-grained sandstone (5) with oil impregnation, 20 cm thick.