Hornerstown Formation

The Hornerstown Formation is a Paleogene or latest Mesozoic geologic formation in New Jersey.[1] The age of these deposits have been controversial. While most fossils are of animals types known from the earliest Cenozoic era, several fossils of otherwise exclusively Cretaceous age have been found. These include remains of the shark Squalicorax, the teleost fish Enchodus, several species of ammonite, and marine lizards referred to the genus Mosasaurus. Some of these remains show signs of severe abrasion and erosion, however, implying that they are probably re-worked from older deposits. Most of these fossils are restricted to the lowest point in the formation, one rich in fossils and known as the Main Fossiliferous Layer, or MFL. Other explanations for the out-of-place fossils in the MFL is that they represent a time-averaged assemblage that built up and remained unburied during a time of low sediment deposition, or that they were stirred up from deeper in the sediment and deposited together during a tsunami.[2]

Hornerstown Formation Stratigraphic range: Danian ~65 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Underlies	Vincentown Formation
Overlies	New Egypt Formation and Tinton Formation
Location
Region	New Jersey
Country	USA