They recovered many cremations and developed the phrasing that still dominates much of what is written about Stonehenge. As part of service trenching in 1979 and 1980, Mike Pitts led two smaller investigations close by the Heelstone, finding the evidence for its neighbour. More recent excavations have been held to mitigate the effects of electrical cables, sewage pipes, and a footpath through the site. Since 2003, Mike Parker Pearson has led investigations in the stones area as part of the Stonehenge Riverside Project in an attempt to better relate Stonehenge to its surrounding environs. National Geographic Channel screened a two-hour documentary exploring Parker Pearson's theories and the work of the Riverside Project in depth in May 2008. In April 2008 Professor Tim Darvill of the University of Bournemouth and Professor Geoff Wainwright of the Society of Antiquaries excavated a small area inside the stone circle It is hoped this will establish a more precise date for the earliest stone structure that occupied the Q and R Holes. From 2005 excavation of the area around a spring pool known as Blick Mead about a mile from Stonehenge, have taken place under the direction of Professor David Jacques of the University of Buckingham. These have revealed the earliest settlement in the area dating to the period 7900 BC to 4050 BC. Britain's Bournemouth University archaeologists, led by Geoffrey Wainwright, president of the London Society of Antiquaries, and Timothy Darvill, on September 22, 2008, found it may have been an ancient healing and pilgrimage site, since burials around Stonehenge showed trauma and deformity evidence: "It was the magical qualities of these stones which ... transformed the monument and made it a place of pilgrimage for the sick and injured of the Neolithic world." Radio-carbon dating places the construction of the circle of bluestones at between 2,400 B.C. and 2,200 B.C., but they discovered charcoals dating 7,000 B.C., showing human activity in the site. It could be a primeval equivalent of Lourdes, since the area was already visited 4,000 years before the oldest stone circle, and attracted visitors for centuries after its abandonment.