Stonehenge, which is in the west of England, is one of the world's most famous prehistoric monuments. english heritage
The ancient site attracts around one million visitors a year. The unique stone circle was erected in the late Neolithic period about 2900 BC. Peter Macdiarmid/Getty Images Europe/Getty Images
The very large standing stones at Stonehenge are made from 'sarsen', a local sandstone, but the smaller ones, known as 'bluestones.' Adam Stanford © Aerial-Cam Ltd.
The new discoveries may also help to understand why Stonehenge was built. Parker-Pearson worked alongside a number of archeologists from different universities. Adam Stanford © Aerial-Cam Ltd.
The Stonehenge bluestones are of volcanic and igneous rocks, the most common of which are called dolerite and rhyolite. Adam Stanford © Aerial-Cam Ltd.
Stonehenge was built during the Neolithic period, between 4,000 to 5,000 years ago. Both of the quarries in Preseli, Pembrokeshire were exploited in the Neolithic era, and Craig Rhos-y-felin was also quarried in the Bronze Age, around 4,000 years ago. Adam Stanford © Aerial-Cam Ltd.