This prehistoric monument 8 miles north of Salisbury (UK), is an architectural and engineering triumph. It is composed of stones uniquely crafted and carved with interlocking joints by way of uprights and lintels. Two distinct types of rock were used – sarsen, which is an extremely tough limestone, and blue stones made of spotted dolerite. Dolerite is a very rare volcanic rock and is only found in one known location which is 240 miles west of Stonehenge in the Preseli Mountains of South Wales. These rocks were originally thought to have been transported by humans. Another theory that has recently gained support is that they were brought much nearer to the site by the Irish Sea Glacier which flowed southwards from its source areas in Scotland, Ireland and Wales.
*image from web