Geology Site Account

Site name: Farnham Wood Puddingstones

Grid reference: TL 4818 2546

Brief description of site:

A giant boulder of Hertfordshire puddingstone 1.83 metres (6 feet) long sits in Farnham Wood a few metres north of the public footpath. A second, smaller puddingstone sits alongside which is a fragment that has broken off the main mass.

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Site description

A giant boulder of Hertfordshire puddingstone 183 x 120 x 100 centimetres in size sits a few metres north of the public footpath through Farnham Wood. A smaller puddingstone 92 x 70 x 45 centimetres in size sits alongside, which is a fragment that has broken off the main mass. These stones are in fairly ‘fresh’ condition, providing good evidence that they may be derived from a nearby in-situ deposit of puddingstone.

These puddingstones were first discovered by Jacqui Farrants and Paul Bentley while researching their book 'Puddingstone Walks in Essex' .

Hertfordshire Puddingstone is an extremely hard rock with an interesting history.

About 60 million years ago, shortly after the extinction of the dinosaurs, this boulder was part of a beach of flint pebbles on the coast of a subtropical sea. About 55 million years ago the sea had retreated and the layer of pebbles was situated beneath the soil in a hot, dry climate similar to that of the Kalahari Desert today. During this time the pebbles were cemented together by quartz, forming an incredibly tough layer of rock.

During the Ice Age, about half a million years ago, rivers and glaciers broke up this layer and scattered the fragments over Hertfordshire and Essex. This boulder is one of these fragments and the original flint pebbles can be clearly seen. Puddingstone is so called because the pebbles give it the appearance of a plum pudding. It is usually called Hertfordshire Puddingstone because these boulders are most commonly found in East Hertfordshire. Some puddingstone is very colourful and in Georgian and Victorian times it was often cut and polished to make jewelry and decorative items such as snuff boxes.

The Farnham Wood Puddingstones. Photo: G.Lucy