Chert and flint are crystalline (perhaps more accurately described as microcrystalline) forms of rock that man has made use of from Stone Age times. The crystals consist of a microcrystalline form of silica, more commonly known as quartz (silicon dioxide). Flint is the better-known form of this substance and is commonly found as very hard concretions in deposits of chalk. It is so hard that, when the chalk is eroded, the flint remains in an almost undamaged state.
When fractured, flint and chert nodules disintegrate to produce conchoidal, glass-like breaks, and this creates sharp edges capable of inflicting physical damage. When controlled, this damage can be put to practical use and early species of man (Homo erectus, H habilis, H neanderthalensis and early H sapiens) recognised this fact and put it to good use in their everyday lives. During the Ice Ages, spreading ice sheets eroded many millions of flint nodules from chalk deposits and spread them all over the UK. When the ice melted during warmer interglacial periods, the nodules were deposited wherever they happened to have been transported to. Such flint nodules are referred to as “derived” nodules. Early man came to recognise them and collected them to make use of their physical properties. In this way, the first stone tools appeared and, as skill levels developed in their manufacture, they became more and more sophisticated in form. The tools were used for different purposes and each purpose resulted in the production of a tool of a particular generic form. Examples include the very familiar handaxes (used for general chopping purposes), hammerstone implements (used for striking and breaking), side-scrapers (used for cutting meat from hides and trimming samples of hide to make clothing) and many others, all of which can be recognised with a little experience.