Left: Inter-Basin Correlation. The lake-level cycles in the Towaco Formation of the Newark basin are also present in the East Berlin Formation of the Hartford basin. In fact, there is a one-to-one correlation between the lake-highstand deposits in both basins. The geochemistry of the Holyoke Basalt is also the same as the Preakness Basalt, and the geochemistry of the Hampden Basalt is also the same as the Hook Mountain Basalt. Diagram courtesy of P.E. Olsen.

Below: Lake-level cycles in outcrop of the East Berlin Formation, Hartford rift basin, Cromwell, CT. Three lake-level cycles are present in this roadcut. The deepest-water deposits are black shales present at the two lamp-posts and to the right of the geologist at the center of the photo. The black shales are surrounded by gray mudstone, which in turn are surrounded by purple, beige, and red massive mudstones. Photo by Roy Schlische.