GEOLOGY AND PALEONTOLOGY OF A NEW UPPER CRETACEOUS (MAASTRICHTIAN) PALEOGENE TRANSITION SITE (K-Pg) DISCOVERED NEAR MULLICA HILL, GLOUCESTER COUNTY, NEW JERSEY

The Turtle Creek tributary of Raccoon Creek near Mullica Hill, Gloucester County, New Jersey, exposes the contact between the Upper Cretaceous (Maastrichtian) Navesink Formation and the overlying Paleogene Hornerstown Formation, a nominal K-Pg transition site. The stratigraphy at Turtle Creek is disturbed. In some sections the Kirkwood makes an appearance, but the expected intermediate Vincentown Formation is entirely missing. Although the site is near the historic prolific Mullica Hill Pond site, fossils native to the same formations exposed at Turtle Creek are relatively sparse. Cucullaea sp. steinkerns and  fragments that appear to be bone were recovered just above the K-Pg contact at the expected horizon of the Main Fossiliferous Layer (MFL) characteristic of K-Pg sites on the Coastal Plain. The Navesink and Hornerstown Formation exposures yield fossils typically associated with these formations including Cucullaea and Pycnodonte bivalves as steinkerns, an indurated Exogyra and other bivalves, Peridonella dichotoma and lithified Thalassinoides burrows. Silicified wood fragments found in the stream bed gravel correlate with the Kirkwood Formation which outcrops in a downstream section. All fossils at this site are poorly preserved except the silicified wood and the sponge Peridonella dichotoma. Stratigraphy reveals an unexpected layer of gravel with embedded cobbles and boulders with Paleozoic fossils above the Hornerstown and Kirkwood Formations attributed to the Bridgeton Formation several kilometers outside of its mapped bedrock range. Some of the clasts exhibit striations and other evidence of glacial derivation. The site is unique for abundant Paleozoic fossils representing Cnidaria anthozoans: tabulata and rugosa, porifera, crinoidea and brachiopoda taxa traced to the tentative Bridgeton Formation hosting layer. Systematics and photographs for all invertebrate native fossils recovered from the site and representative Class taxa of the Paleozoic fossils are included.