Early Jurassic stratigraphy of the Newark basin based on numerous ACE cores (red) and the NBCP Martinsville core (purple). Depth rank is a relative measure of lake depth, which fluctuated from shallow (0) to deep (5) on a fairly regular basis The Triassic-Jurassic boundary (green line) is located in the uppermost Passaic Formation. Each of the three basalt-flow formations contains at least three flow units. Click on the image to see a larger version. Modified from Olsen et al. (1996).