New Jersey amber

New Jersey Amber, sometimes called Raritan amber, is amber found in the Raritan and Magothy Formations of the Central Atlantic (Eastern) coast of the United States. The amber is dated to be of Late Cretaceous, Turonian age, based on pollen analysis of the host formations. The amber has been known since the nineteenth century, with several of the old clay-pit sites now producing many amber specimens for study. A number of organism fossils have been described from inclusions in the amber, including fungi, plants, tardigrades, insects, and feathers. The first identified Cretaceous age ant was described from a fossil found in New Jersey in 1966.

Though named after New Jersey, the fossil-bearing strata of the Raritan and overlying Magothy formations are also exposed in several neighboring U.S. states, including Maryland through south and central New Jersey, across Staten Island and Long Island (coastal areas of New York state), to a northern exposure at Martha's Vineyard, an island of Massachusetts.

Of the two formations that New Jersey amber is found in, the Raritan Formation underlies the Magothy Formation. The Magothy formation is reported by Wilson's 1967 paper describing Sphecomyrma freyi as having exposures in Maryland, New Jersey, New York, Delaware, and other unspecified islands along the New England coastline. The formation consists of gray to dark brown clay beds interlayered in light-colored sands. In the clay layers are lignite lenses, leaf impressions, and the amber. At the time of the paper's publication, the age was uncertain, and given by Wilson and Carpenter as approximately 100 million years old. Amber deposits of the Raritan Formation are mainly in the Old Bridge sand member and South Amboy Fire Clay Member, with the latter being fossilized in situ, with no disturbance after deposition. Palynological dating of the South Amboy Fire clay has returned a Turonian age, placing the members in the Complexiopollis – Santanacites palyzones.

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