_Natural wonder of Norfolk: Flint

If there’s one material that’s synonymous with Norfolk then it’s flint. You’ll see it everywhere, particularly picturesque in the coastal cottages of north Norfolk and in churches across the county. Before brickmaking, it was a freely available building material, particularly when in the hands of skilled knappers. 

One of its earliest uses for construction can be seen at the Roman Burgh Castle near Great Yarmouth. Head there to also catch amazing sunsets over Halvergate Marshes and imagine how the view would have been to the sandal-wearing Italians… 2000 years ago there would have been no seaside resort at all and all of what you see in front of you was water, the mouth of a mile-wide estuary that went straight out to sea, punctuated by small islands.

Visit the Brecks in the west of the county to Grime’s Graves near Thetford and you can see the earliest evidence of flint mining. This area was a unique source of hard black flint. Head down the one open 57-foot deep shaft and you’ll see where 4,500 years ago Neolithic people created one of Europe’s earliest industrial centres. There are more than 400 digs which are still visible.

Grime’s Graves is a misnomer. There are no burials to be found here. The word graves actually means pits or mines.

It makes for a pocked landscape redolent of 20th century wars, for which flint helped lay the groundwork.

Named after the Devil’s holes of the pagan god Grim, the miners used the flint to expertly fashion all kinds of blades, from scrapers and knives to axes and spearheads, and later, flintlocks for firearms – they were mass-produced here in the Brecks for the Napoleonic wars.

Flint comes from spicules of billions of ancient sponges. Unusual chemistry in the ocean that covered East Anglia about 70-90 million years ago led to the silica from sponges being dissolved in seawater. The silica then solidified out of the water to form flint in sedimentary rock formations.

Found naturally in chalk, with layers in various shapes and sizes, flint is almost pure silica, but any impurities give different colours: brown field flints eroded from the chalk around Fakenham; black flint around Thetford and Swaffham; chalk-covered grey flints north of North Walsham; light grey around Holt; rounded beach flints near Wells-next-the-Sea, Sheringham and Cromer.

Flint is a very hard black mineral similar in composition to glass, which when worked correctly, is capable of a very sharp cutting edge.

Norfolk has become famous for its evidence of early human occupation. Among the finds have been a selection of black flint tools left behind 60,000 years ago near Lynford, in the Brecks, where flint tools were found with mammoth bones. Likewise, a 500,000-year-old flint axe was found at Happisburgh on Norfolk’s Deep History Coast.

Without good available building stone and before brick-making was widespread in the later Middle Ages, flint, either knapped or unknapped (the word knap comes from the Dutch/German word krappen, to crack), was used since antiquity as a material for building stone walls, using lime mortar, and often combined with other available stone or brick rubble.

Norwich’s Guildhall has some of the best medieval flintwork in existence, but there are good examples of its use across the county, including the Roman Burgh Castle near Great Yarmouth, Norwich city walls including the Cathedral, Pulls Ferry by the River Wensum and the cobbled Elm Hill, Castle Acre Priory and the ruins of Thetford Priory. There is amazing flintwork in all Norfolk's medieval churches, of which the county has the highest concentration in Europe.

Puzzling giant flint formations known as paramoudras (pot stones) can be found on low tide beaches at Beeston Bump and West Runton and sometimes exposed in the chalk cliff.

What are the best churches and cathedrals in Norfolk