Purbeck Limestone History
The United Nations Educational, Scientific and Cultural and Organization (UNESCO) granted the coastline World Heritage status. The
internationally protected site is now called the “Jurassic Coast”. A more appropriate name for the region would be the Mesozoic coast,
but Jurassic has a popular culture association due to the “Jurassic” Park movies, where fictional dinosaurs have been reintroduced into the present by scientists.
This Mesozoic includes three well known periods called the Triassic, Jurassic, and Cretaceous periods and is an interval of geological time from about 252 to 65.5 million years ago, it is also called the Age of Reptiles.
A mass-extinction of the Dinosaurs marked the end of the Mesozoic Era.
Leger A. 2006 from the University of Colorado, USA states:
".....The Purbeck limestone spans from the lower Cretaceous 140–125 million years ago down to the upper Jurassic 150–145 million years
ago. The Purbeck stone is a large grained limestone that originated in soft lime muds, shells and other fragments
of organisms living in the water. Below the Purbeck limestone lies the Portland limestone
that consists of smaller grains of calcite clasts. The Portland limestone, commonly called “free stone”, is a high quality
working stone for building. However, in the towns and villages of Dorset both the limestones are found.
The more important characteristic of the limestone is their strength against erosion. Despite their differences the Purbeck
and the Portland limestones share this quality. Compared to surrounding layers these limestones are very resistant and
will often form ridges 14...."
Dr Ian West, a retired geologist from Southampton University states that:
...Durlston Bay, Swanage is the type-section of the Purbeck Formation and the geology has been much
studied since it was first described by Thomas Webster in 1816. This classic Purbeck section
of lagoonal and lacustrine limestones alternating with shales and marls is the thickest exposed on
the coast. Shelly limestones, the Purbeck Stone and Purbeck Marble, have long been quarried. Remains of dinosaurs, mammals, turtles, pterosaurs, crocodiles, fish, isopods and insects have been found here...