Talk – Geoarchaeology of puddingstone in Hertfordshire and Dorset

Dorset Geologist’s Association Group (DGAG) will host a talk on the Tuesday 17 October 2023.

Title: Geoarchaeology of puddingstone in Hertfordshire and Dorset

Speaker: Mervyn Jones with a talk mixing in archaeology with geology. The talk is based on a recent publication co-authored by the speaker in the Proceedings of the Geologists’ Association in Feb 2023.

Time: Talk will start at 7pm; finish approximately 8pm Venue: Activity

Meeting Room: Dorford Centre, Bridport Road, Dorchester, DT1 1RR

Lecture Entry Cost: £6 (£5 for DGAG members) collected on room entry

Booking a seat: Contact DGAG events at email:

Talk Description: Discontinuous lenses of pebbly conglomerate have been silicified to create concretions of Hertfordshire Puddingstone. These 2–3 m of Paleogene silt-sand and gravel draping the Chalk were investigated using geological and archaeological techniques. Dissolution features in the chalk created 93 dolines, the largest concentration in the Chilterns. These were exploited by the Romans as valuable raw material for quern-making. Shortly after the Roman Conquest in AD43 the site was cleared by felling and burning the tree cover. The cortex and poor-quality core stone were cut away from concretions with picks, manageable slices were detached using steel wedges and initial shaping was undertaken to produce blanks of querns to be finished elsewhere. Quarrying continued for, at most, fifty years. The excavated doline fills and rims around the pits taken together form the second largest remaining area of Roman ground surface in Hertfordshire. The site was abandoned and has been largely undisturbed apart from some quarrying of chalk and brickearth and offers further opportunities for research. These findings will be contrasted with the pebbly Sarsen of Dorset and its use by neolithic people, including the recent discovery of a polissoir (“polishing boulder”) in the valley of stones – see

Photo: Screen shot photo courtesy of Wikipedia

References Website links:
Feb 2023