Flint is a dark, often translucent stone usually of a black colour, although it can also be amber or brown depending on iron or other impurities. It originates from the same geological processes that formed the chalk that underlies most of eastern England.

Flint is found in the chalk in extensive layers called “floors” or between them as “pot-stones.” In the freshly quarried state, it comes out as irregular lumps of rounded cross-section full of holes and branches with dark glass-like split faces where the lace-work of the floor has broken up. The rest of the surface is covered with a thin bonded-on white layer of chalk, hence the name “Lime Flints.”

Flint also collected around vertical runnels running through the chalk. There it formed as irregular hollow-centered wheel-like shapes of various sizes called “pot-stones.” Again most of these are split apart at the weakest points, but unbroken ones can be found, sometimes as much as a yard (meter) across.

When eroded by river rolling, pounded by sea water or churned in the outflow of glaciers, broken pieces of flint tend to form very regular rounded cobbles of various sizes, usually with a matte grey surface that darkens when wet. Often they are so round that in the past and with careful grading they have sometimes been used as cannon balls. From a Norfolk cottage builder's point of view, the most convenient source of suitable construction flints were the beaches of North East Norfolk, particularly in the Sheringham area.

Historically, due to both geological reasons and the action of the sea, Sheringham cliffs had acquired huge bastions of neatly rounded cobbles, which jointly served as sea defenses, a handy spot to park your crab-boat and a resource for the local building industry. Unfortunately, owing to over-exploitation, this latter use has proved seriously un-sustainable. So many were carted away by the locals and later by the railways for use as a major raw material in the Staffordshire Potteries, that beach quarrying had to be forbidden, for fear of wave erosion collapsing the cliffs.

Sheringham beach cobbles, and to a lesser extent drifts of wave rolled flints from other places along that stretch of coast, can be found as a walling material for miles inland. The size of the cobbles in the wall being a rough guide to its age, since flints were so selectively removed from the beaches that the supplier, O. F. Neptune Esq. was unable to keep up with the supply of the larger, more desirable sizes.

Further inland, flint had to be dug out from the underlying chalk. Apart from a few special situations such as at Grime's Graves (see note) and the tunnels under and around Norwich, quarrying flints was done largely as a sideline to the production of lime and marl for agricultural purposes. A method of improving the land which is first mentioned by Pliny the Elder in Roman times, and used to an increasing extent ever since.

“Lime Flints” are very different from “Beach Flints” and require very different construction techniques, but more on that tomorrow.

— • —

Tomorrow: Building with Flint.

Sunday next: Brandon and Grime's Graves on Mardlingham Parish Notice Board.

FIRST — PREVIOUS — NEXT — LATEST