Petrology
By identifying the nature of the so-called bluestones at Stonehenge, and locating their source in Pembrokeshire, H.H Thomas in 1923 demonstrated a new source of archaeological information. Since then many British polished stone axes have been sliced – a sliver of stone between two saw cuts is detached, ground down, and its mineral content identified under the microscope. Many distinctive groups have been recognized. Most can be pinned to a limited source, the only accessible outcrop where their content can be closely matched. At a few of these the axe factory has been located. A Neolithic axe found in Chalfont St Peter was found to come from Great Langdale in Cumbria and a Bronze Age perforated axe from Hulcott was a glacial erratic after petrological analysis.
