Caro wrote:

How did they know there was flint there so deep?  And are there others in Britain?

I’m no geologist but my own experience growing up on the Kent coast is that chalk and flint go together. In other words where there is chalk there is flint and there are always plenty of pieces of flint and even seams of flint visible in white cliffs. The downs of Kent and Sussex are generally chalky and ancient flint workings are evident at various locations along them notably at Harrow Hill near Patching:

http://www.sussexarch.org.uk/saaf/harrowhill.html

None of them are open to visitors (as far as I know) which makes Grime’s Graves in Norfolk unique in this. I would suspect that the Breckland (where Grime's Graves is located) is also a chalky area. This geological characteristic continues under the British Channel to Belgium and Northern France most famously under the wine-producing regions of Champagne and Burgundy. Is it possible that Neolithic people worked out that where soil was good for vines then flint wouldn’t be far away? Either that or else seeing bits of flint on the surface could well have been an indication of more down below.

Whatever their divining method, they certainly appreciated that subterranean flint is much better to work with than exposed flint. The latter is too brittle and shatters easily (literally into smithereens) as my school friends and I discovered in our rather pathetic attempts at making flint tools from pieces of the rock picked up on the sea shore.

P.S. Note in the link above the reference to ‘unbelieving archaeologists’ causing little people to emigrate. Tut tut.

Sussex born and bred, I concur with Viz that generally chalk means flint, and they can be clearly seen to go together where there are exposed cliffs. The sea cliffs, such as at Beachy Head or Pegwell Bay, show that some layers of chalk, particularly the upper ones, contain much less flint, and also that in some layers the flint is as rounded nodules while in others it is more as flat slabs (tabular flint). Chalk is quite a soft rock and so inland exposures are quite rare: nowadays fresh cuttings through chalk, for roads or railways, usually get masked with vegetation and a thin soil layer within only a decade or so. Unlike the harder Carboniferous limestone of the Yorkshire Dales which forms the well known cliffs, scars and limestone pavements, there are almost no naturally occuring exposures of chalk rock other than continually eroding cliffs along the coast.

But chalk has been dug for many centuries not only, and perhaps not primarily for flint. Chalk has probably been excavated since neolithic times for lime - either as the basis of simple lime cement, or possibly in even greater quantities simply to spread onto fields to counter the natural acidification that comes from constantly growing crops on the same piece of land. Pliny the Elder mentions the English practice of quarrying chalk for liming the land and it was still being regularly practiced in the nineteenth century.

Digging chalk to spread lime on the land is one suggestion for the excavation of the so-called Deneholes that occur throughout the chalklands of southern England. These are pits/shafts typically a metre or two in diameter and extending down, through the sub-surface layer of weathered rock, to the clean pure chalk at anything up to about 20m down (probably the practical limit of early mining technology) where typically the shaft bells out as an excavated chamber. I'm not saying that chalk mining pre-dates flint mining, but the technology is the same and people were probably well aware of the geological association of good unweathered chalk occurring alongside good unweathered flint, but only at several metres depth underground.

As an aside, I've been down several Deneholes ... Imperial College Caving Club, in 1985 I think it was, were contacted by Hertfordshire Police to abseil into several of these shafts as part of the hunt for Mrs Ann Lock who had gone missing under somewhat suspicious circumstances some weeks earlier. We didn't find her (her body was eventually found some time later hidden in a shallow grave alongside a railway line) but these ancient chalk mines are certainly impressive, even after centuries of debris and rubbish falling, or being thrown, into them ... especially when you think that they were entirely excavated by hand, possibly just using antler picks and simple wooden shovels, with presumably just a rope and windlass to haul the rock up to the surface.

I read some time ago a description of how old - Roman? - chalk mines in the North-Eastern parts of France was almost perfect for the second maturing of Champagne wines.

Chalk cliffs and boulders showing embedded flint.




Roman chalk mine used as wine cave in Champagne.

To go with the subterranean wine ... Roquefort cheese is matured in the limestone caves of the Cevennes: the mould (Penicillium roqueforti) that gives the distinctive character is naturally found in the soil of these caves.

And the numerous galleries of the sandstone mines at Merston near Oxted in Kent, were used, once stone extraction had come to an end, as a huge mushroom farm which operated for much of the 20th century.

Mining (actually underground quarrying) started here in the 17th century for a particular layer of Upper Greensand rock which occurs immediately under the chalk. This stone was primarily used in the construction of furnaces associated with the Wealden iron industry because of it natural fire resistant properties and hence it was often called 'firestone' or 'hearthstone'. Later in the 19th century a fashion developed for whitening domestic stone hearths, doorsteps and window ledges by rubbing hearthstone into them which left a white chalky deposit when it dried out, and which provided a convenient additional market for small stone offcuts just as the main iron-industry business was coming to an end. The desirable stone layer is only a little over 1m thick and so was worked using oxen rather than taller pit ponies ... and I can attest that exploration of the miles of galleries is back-breaking, as the roof is just too low to be able to stand, and so you have to move at a half crouch/sideways shuffle.

Some years ago a friend and I went on a guided tour of the Chislehurst Caves (Kent - though not I think on the Icknield Way).  I've just done a google search www.chislehurst-caves.co.uk/ and it would appear that chalk and flint were mined from them way back when.

Thank you, Vizzer, for showing what I'd only red about.


LiR, crossed posts.

Although Chalk is a fairly soft rock - and as a construction stone it is certainly nothing like Bath Stone, Portland Stone, Carboniferous Limestone, Millstone Grit, marble, andesite or granite - in southern England, where chalk predominates and most other available 'rocks' are soft clays and unconsolidated sands, chalk has long been quarried and used as an architectural stone. Its softness is actually an advantage in some ways in that it can be dug out with just a pick and shovel, and then building blocks can be cut to size and shape with little more than a hand saw. But once extracted and cut to shape, chalk rock slowly dries out and becomes much harder. In Sussex the more solid strata of the chalk, locally called 'clunch', have been used successfully as a building stone for many centuries. The local expression is something along the lines of: it is a good building stone so long as you give it good boots and a hat ... that is it needs a solid raised foundation, and it needs to be capped to protect it against the weather, with either flagstones, tiles, or thatch, or if as part of a building, then simply wide roof eaves. So it's really little different to how one needs to deal with that other, typically southern building technique, wattle-and-daub.

Anyway here's an example of the use of cut blocks of chalk rock with knapped flints, to create a chequer-board effect  - this is the wall of the medieval church of St Michael's at Mickelham in Surrey. This is just a couple of miles from the prominent chalk 'down'  of Box Hill, as well as being close to one of the very few inland sites where chalk is naturally exposed at the surface - not on the hill itself but in the stream-bed of the adjacent river Mole, where the river, a tributary of the Thames, has cut into the bedrock and eroded the bank to expose a small chalk cliff, and in dry weather sinks undergound into true karstic sinkholes ... to then resurge again from several distict springs in the river bank at several miles further downstream.


Chequerboard chalk and flint decoration on St Michael's church (12th century?) at Mickelham, Surrey.