Rockhounding in Monmouth County, New Jersey

Monmouth County

Shark River is named for the fossil shark teeth found where it cuts middle Eocene marine beds, notably the Shark River and Manasquan formations, roughly 45 million years old. A basal quartz sand layer yields shark and ray teeth, while the glauconitic marl above carries molds of clams and other shells. It sits inside a Monmouth County park, so collecting is done through the park's programs or on the exposed gravel bars.

Shark Teeth, Fossils

Monmouth County

Big Brook is New Jersey's best known free fossil stream, cutting Late Cretaceous marine beds of the Navesink Formation that are roughly 70 million years old. Collectors regularly find shark teeth (Squalicorax and Cretolamna), belemnite guards of Belemnitella americana, and Exogyra oyster shells weathering out of the streambed. Monmouth County manages it as public parkland with published fossil-collecting rules, which is rare for an East Coast site.

Shark Teeth, Belemnite, Fossils

Monmouth County

Poricy Brook exposes the same Late Cretaceous Navesink Formation as nearby Big Brook, and its fossil beds are among the most accessible in the state. Belemnites (Belemnitella americana), Exogyra costata oysters, and small shark teeth are common in the streambed gravel. The nonprofit Poricy Park Conservancy maintains a marked trail to the beds and rents sifting equipment on site.

Belemnite, Shark Teeth, Fossils

Monmouth County

Ramanessin Brook is a quieter alternative to Big Brook and Poricy, draining the same Late Cretaceous Monmouth Group marine sequence in Holmdel. Sifting its gravel bars turns up shark teeth (Squalicorax and Scapanorhynchus), ray denticles, and fish material weathered from beds roughly 70 million years old. It runs through township open space, and the Friends of Holmdel Open Space run free public fossil walks along it.

Shark Teeth, Fossils