Take any rock or stone and it has its own story to tell. Rocks range from thousands to billions of years old so their stories can be very long but also incredible.
With careful study a rock can tell you if it’s been melted, shattered, squashed, heated, dissolved, eroded, buried, scraped, rolled, intruded, erupted or even eaten!
The rocks in the cliffs and on the beach at Charmouth are the remains of an ancient Jurassic sea. They are made up of layers of sediment laid down in an ocean around 195 million years ago and contain lots of fossils. The cliffs around Charmouth are part of the Jurassic Coast, England’s first Natural World Heritage site.
Age: Jurassic – around 195 million years old
Composition: Clay or mud and very fine sand or silt
Origin: Mud layers in the cliff
The name Shale has a specific meaning in geology but it is really just a type of mudstone.
Shale is usually less sticky than other mud rocks because it has some coarser grained material in it like fine sand or silt. Geologists identify silt from mudstone by grinding a little between their teeth! If it's slightly gritty then it's not shale.