Sarsen

Sarsen stones are sandstone blocks found in quantity in the United Kingdom on Salisbury Plain, the Marlborough Downs, in Kent, and in smaller quantities in Berkshire, Essex, Oxfordshire, Dorset and Hampshire. They are the post-glacial remains of a cap of Cenozoic silcrete that once covered much of southern England – a dense, hard rock created from sand bound by a silica cement, making it a kind of silicified sandstone. This is thought to have formed during Neogene to Quaternary weathering by the silicification of Upper Paleocene Lambeth Group sediments, resulting from acid leaching. The word "sarsen" (pronunciation ['sa:sǝn]) is a shortening of "Saracen stone" which arose in the Wiltshire dialect. "Saracen" was a common name for Muslims, and came by extension to be used for anything regarded as non-Christian, whether Muslim, pagan Celtic, or other.