The oldest known Neolithic flint mine in England, in Norfolk, with the remains of around 350 mine shafts. The high-quality flint had three banks: floorstone, wallstone, and topstone. The products, mainly ax blades, were roughly chipped to shape at the site and were then traded in semi-finished condition. The miners used flint tools, deer's antlers as picks or wedges, and animal shoulder blades as spades. Excavation was probably by wooden shovel (a product of the polished ax and chisel) or possibly the shoulder blades of oxen. It is estimated that 50,000 picks made of red-deer antler were used during the 600 years of activity in the mine, which began about 2300 BC. In one shaft, the miners made a chalk statuette of a fat pregnant woman and a phallus of chalk; this practice, a fertility cult, was used to bring fruitful results in further mining. There are differing dates for the use of the mine shafts.