This large stone is a sarsen stone which was formed 5-10 million years ago. Sarsen stones are found scattered on the surface of the Berkshire and Hampshire chalk downs and many other places in the South of England. They are believed to be the remains of a post-glacial hard layer of rock formed by the concentration of elements in hot, dry conditions with seasonal rains, similar to the climate in modern Africa or Australia. Sarsens are often used as corner stones, gate posts or stepping stones. This stone used to be exhibited outside the museum on the balcony.
Period: Cenozoic
Place: West Berkshire