While quarrying limestone in 1786, workers came to a bed of sand about 50 feet below ground level. In the layer of sand, however, they found the stumps of stone pillars and fragments of half-worked rock. Digging further, they found coins, the petrified wooden handles of hammers, and pieces of other petrified wooden tools. The sand in which the discovery was made was beneath a layer of limestone dated at 300 million years old.