Major ceremonial monuments called henges, including sites…

Major ceremonial monuments called henges, including sites at Avebury, Woodhenge, and the first phase of Stonehenge, had been constructed in the late fourth millennium.

Archaeological excavation has indicated that timber was abandoned at Stonehenge around 2600 BCE in favor of stone and two concentric crescents of holes (called the Q and R Holes) were dug in the center of the site, although there is little firm dating evidence for this phase, called Stonehenge 3.

The holes held up to eighty standing stones, forty-three of which, the bluestones (dolerite, a holocrystine igneous rock), were thought for much of the twentieth century to have been transported by humans from the Preseli Hills, two hundred and fifty kilometers away in modern day Pembrokeshire in Wales.

A current (2007) theory is that the bluestones were brought from glacial deposits much nearer the site, which had been carried down from the northern side of the Preselis to southern England by the Irish Sea Glacier.