Late Triassic - Early Jurassic stratigraphy of the Newark basin based on numerous ACE cores (red vertical lines) and the NBCP Martinsville core (purple vertical line). Depth rank is a relative measure of lake depth, which fluctuated from shallow (0; red mudstone) to deep (5; black shale) on a fairly regular basis. Each of the three basalt-flow formations contains at least three flow units. Modified from Olsen et al. (1996b).