Where to find ammonites

Frequently asked questions

Where is the best place to find ammonites?

Charmouth and Lyme Regis on the Jurassic Coast are the most reliable starting points in the UK. Both beaches are free to access, and fresh material falls from the Blue Lias and Charmouth Mudstone cliffs after every storm. Search the foreshore scree rather than the cliff face itself. Whitby on the Yorkshire coast produces Jurassic ammonites from the Whitby Mudstone Formation; the beach below the cliffs at the north end of town is the most productive stretch. For Devonian goniatites (an ancestral ammonoid group), the Erfoud region of southern Morocco offers paid or informally arranged quarry access where you can find goniatite-bearing limestone directly. Each site suits a different collector: Charmouth is best for beginners with families, Whitby rewards early-morning persistence, and Morocco is worth the journey if you want Devonian material you cannot find in Europe.

How do I identify an ammonite?

Ammonites are coiled in a flat plane, unlike the helical coil of most modern snail shells. The most reliable identifying feature is the suture line: the boundary between each internal gas chamber, visible on the outer surface as a complex zigzag or frilled pattern. Modern snail shells have no sutures. Most ammonites also have pronounced ribbing that follows the curve of the coil, and some species show nodes or keels along the outer edge. At the centre of the coil you can often see the siphuncle, a small hole through which the animal regulated buoyancy. If you find a coiled shell with clear suture lines and ribbing, it is almost certainly an ammonite. Smooth spherical shapes without sutures are more likely gastropods or concretions.

How big can ammonites get?

The size range is wider than most collectors expect. Many common Jurassic Coast ammonites are 2 to 15 centimetres in diameter, and these are the specimens you are most likely to find. However, some species grew extremely large: Parapuzosia seppenradensis, a Late Cretaceous ammonite from Germany, is the largest known ammonite — the type specimen in Münster measured approximately 1.74 metres in diameter, and a 2021 study in PLOS ONE (Hoffmann et al.) estimated that a complete shell may have reached around 2 metres or more. At Monmouth Beach in Lyme Regis you can see large ammonites up to 60 centimetres embedded in the wave-cut limestone ledges at low tide. These are fixed in the rock and cannot be collected, but the site is worth visiting for the scale of material alone. Very large loose specimens are uncommon finds at most collecting beaches.

Are ammonites rare?

At well-chosen Jurassic Coast sites, ammonites are one of the most common fossils you will find. Charmouth Beach regularly produces small Asteroceras and Promicroceras specimens from the cliff scree, and a patient morning search usually yields several. Fragments are far more common than complete specimens. Intact ammonites with clear ribbing, visible sutures, and both sides of the shell preserved are less common and reward careful searching. Iridescent specimens with a pearlescent or opalescent sheen are often described as pyritised ammonites; most of these come from commercial sources in Morocco or Russia rather than from UK beaches. If you see an iridescent piece for sale, it has almost certainly been commercially prepared rather than found on a public foreshore.

What geological period are ammonites from?

Ammonites (and their ancestors the ammonoids) appeared in the Devonian, roughly 390 million years ago, and survived until the end-Cretaceous mass extinction 66 million years ago. The entire group went extinct in the same event that eliminated non-avian dinosaurs. Different ammonite species occupied very short time windows, which makes them exceptionally useful to geologists as index fossils for correlating rock layers worldwide, a method called biostratigraphy. The ammonites you are most likely to find on the UK Jurassic Coast are Jurassic in age, between 201 and 145 million years old. Specimens from Morocco's Erfoud region are typically Devonian goniatites, around 370 million years old, representing a much earlier branch of the ammonoid lineage.