Fossil Hunting in New Jersey

New Jersey might not be the first state that comes to mind for fossil collecting, but Monmouth County’s greensand marl streams have produced Cretaceous treasures for over 200 years. In fact, some of the earliest dinosaur discoveries in North America came from New Jersey.

Why New Jersey?

During the Late Cretaceous (roughly 66-72 million years ago), the New Jersey coastal plain was submerged beneath a shallow sea. The sediments deposited during this time — dark greenish-black glauconite-rich marls — are packed with fossils from sharks, bony fish, mosasaurs, and a rich community of invertebrates. Over millions of years, streams have eroded through these layers, concentrating fossils in their gravel beds.

Big Brook is legendary among East Coast collectors. The combination of easy access, shallow wading, and abundant finds makes it arguably the best beginner fossil site in the northeastern United States. A few hours of sifting gravel almost guarantees a handful of shark teeth.

New Jersey also holds a special place in paleontological history: Hadrosaurus foulkii, discovered in Haddonfield in 1858, was the first nearly complete dinosaur skeleton found in North America.

What You’ll Find

Cretaceous marine fossils (~66-72 million years old):

• Shark teeth — Squalicorax, Scapanorhynchus (goblin shark ancestor), Cretolamna, and others
• Belemnites — Bullet-shaped internal shells of squid-like animals, very common
• Exogyra oysters — Distinctive coiled oyster shells
• Fish bones and vertebrae — Scattered throughout stream gravel
• Crab claws — Hoploparia claw fragments

Rarer finds:

• Mosasaur teeth (small, conical, dark-colored)
• Ammonite fragments
• Dinosaur bone fragments (very rare but documented at Big Brook)
• Crocodilian teeth

Paleocene fossils (slightly younger):

• Shark teeth from Hornerstown Formation
• Brachiopods and gastropods

Best Time to Visit

• Late spring (May-June): After spring rains flush fresh gravel downstream
• After storms: Heavy rain is your best friend at Big Brook — check streams 1-2 days after major rainfall
• Fall (September-October): Lower water levels expose more gravel bars
• Winter can work too: Cold-weather visits mean fewer crowds, but dress for wading in cold water

Tips for New Jersey Collecting

1. Wear waterproof boots or old sneakers — you will be wading in shallow streams
2. Bring a small sieve or colander — scoop gravel from the stream bed and wash it to find teeth
3. Look for dark, shiny objects — fossilized shark teeth are typically black or dark brown due to mineral replacement
4. Work the gravel bars — fossils concentrate where the current slows, especially on the inside of stream bends
5. Learn belemnite shape — once you spot your first one, you will find them everywhere
6. Visit after a flood — the best collecting at Big Brook is 24-48 hours after high water recedes
7. Bring a container with padding — shark teeth are small and can break; a pill bottle with cotton works well
8. Check the Big Brook parking area — the Monmouth County Park System maintains a small lot on Boundary Road

Collecting Sites

Legal Rules for New Jersey

Key Geological Formations

• Navesink Formation (Upper Cretaceous)
• Mount Laurel Formation (Upper Cretaceous)
• Hornerstown Formation (Paleocene)
• Vincentown Formation (Paleocene)

Local Fossil Clubs & Museums

• New Jersey Paleontological Society
• Delaware Valley Paleontological Society
• New Jersey State Museum
• Monmouth Amateur Paleontologist Society