Where to find ammonites in the UK

Ammonites are marine fossils, and in Britain they are overwhelmingly a Jurassic phenomenon. The band of Jurassic rock runs diagonally across England from Dorset to Yorkshire, and where it meets the sea it produces ammonites in quantity.

That gives four main areas: the Dorset and East Devon coast, the Yorkshire coast, the West Somerset coast, and the Glamorgan Heritage Coast in south Wales.

Look for flat grey shale and rounded nodules on the foreshore. Split nodules often show a whole ammonite in section, and small pyritised specimens turn up in the fine shingle at Charmouth and Port Mulgrave.

The large ammonites set into rock ledges at Lyme Regis, Kilve and Robin Hood's Bay should be photographed and left. They are the reason those sites are protected.

The Gault Clay at Folkestone produces beautifully preserved Cretaceous ammonites, often retaining original shell, and the Red Chalk at Hunstanton contains them too. Both are worth knowing about if you are in the south-east or East Anglia.