In 1958 and 1959 the late Christopher Houlder excavated a number of Neolithic quarry pits at Mynydd Rhiw, at the tip of the Llŷn peninsula. He interpreted these as evidence for a small cottage-industry providing stone axes to communities in Wales and the Borders. In 2004, the Museum revisited the site and began a programme of geological and topographic survey and excavation across the mountain.
The results have, to date, demonstrated that quarrying was far more extensive than previously realized, covering some hundreds of meters and involving quarrying to a depth of at least two meters in places. This activity has been dated to between 3700 - 3000 BC, with later use of the hill being demonstrated through the presence of charcoal dating to Early and Late Bronze Ages, the finding of a jet button, and the presence of burial cairns just above the quarries. Equally importantly, the work has shown that this quarrying was not focused on long distance exchange networks, but instead provided a source of high quality rock for the manufacture of stone tools which were then used locally.