What’s in a name?

This is the youngest or highest specimen in the Beaminster Museum collection, recovered from the rock layers exposed in the nearby Horn Park Quarry. It comes from the Zigzag Bed after the fantastically-named ammonite Zigzagiceras first identified at Zigzag Hill Quarry, near Sherborne. Many ammonites evolved very rapidly through time and therefore they can be used to determine the relative age of the rocks in which they are found. These time periods are known as ammonite zones. If you search for ‘Zigzag ammonite’ on the web, you’ll find references to the ‘Zigzag Zone’ as far away as Portugal and even Russia!
This is also the only ammonite in the Beaminster Museum collection on display from the Bathonian Stage. Periods, like the Jurassic, are divided up into a series of stages named after the places that have the best rock record for that time zone. The Bathonian, not surprisingly, is named after Bath, so you can guess where the Kimmeridgian gets its name…

Horn Park Quarry is the smallest National Nature Reserve (NNR) in Britain, being just one acre or 0.32 hectares in size. It was once a working quarry but it is no longer and the remaining outcrop is protected by a fence. There is no collecting other than for scientific and educational purposes. A section of the fossil beds have been stripped back and protected from the weather by a removable cover. To arrange a visit, contact the Senior Reserve Manager on 07899 731404.

Find out more about ammonites on the molluscs pages.


Common name


Scientific name

Parkinsonia pachypleura


Molluscs > Cephalopods


Inferior Oolite

Time period

Middle Jurassic


174 million years

Where found

Horn Park Quarry

Found by

Bob Chandler


Beaminster Museum

Accession number

BM 2011-43-11