The Stunning Jurassic Coast
An Adventure in Place and Time
Some people travel to get away "from it all" or for a few days of relaxation; some people travel to experience new cultures or to see famous historic sites. I love to swim in the sea, to relax on sunny beaches, to try new restaurants, but this page is about one of my favorite places in England. The Jurassic Coast of Dorset, in southern England, is an adventure in place and time.
This stunning coastline runs from Orcombe Point, in East Devon, to the Old Harry Rocks, in East Dorset. It is a World Heritage Site stretching around 96 miles and 180 million years. The coastline consists of Triassic, Jurassic and Cretaceous cliffs, with public access along its entire length on the South West Coast Path.
All the photos and illustrations on this page are copyright to me, and can only be used with my written permission.
The Old Harry Rocks - An iconic coastal rock formation in Dorset
The Old Harry Rocks are a famous landmark on the Dorset Coast, near Swanage. The coastline here is stunning, with caves, arches, stacks and stumps carved from the chalk. Weathering, erosion and hydraulic action have all played a part in the formation of the Old Harry Rocks from the chalk headland of Ballard Point.
The Story of the Jurassic Coast
The Jurassic Coast - How it came to be
There are good reasons why this coastline was designated as a World Heritage Site - it shows amazing examples of natural landforms and rock structures, including Lulwoth Cove, Durdle Door and the Old Harry Rocks. It includes a varied geology and stretches of concordant and discordant coastlines.
The area has been studied in detail, and has a fascinating geological history, which begins with the laying down of different rock types as the continents moved and sea level rose and fell. The oldest rock in the area is Portland Limestone, a hard and resistant rock. Over this Purbeck Limestone, Clays, Greensand and Chalk layers were deposited in their turns.
In brief, as Africa moved up towards Europe, the rock layers were crushed and distorted so that the limestone layers are now tilted to the east. The layers in the west were raised and exposed to erosion. In places Triassic and Jurassic rocks that had been buried for millions of years were exposed. In the Cretaceous period, seas flooded across this eroded surface and new rocks (Greensand and Chalk) formed on top.
Over the last 65 million years, sea level changes and erosion have carved into the rocks to create the coast we can see today.
Have You Visited Yet?
Which is your Favourite Place on the Jurassic Coast?
The Official Guide to the Jurassic Coast
This excellent guide will tell you about the World Heritage Site, how it is managed, and all the best places to visit. Take a walk through time with these stunning coastal walks.
Stair Hole - A spectacular Feature of the Dorset Coastline
In this photo of Stair Hole, you can see the twisted layers of limestone, as well as blow holes and caves carved by the actions of the sea.
Formation of Stair Hole - illustrated in 4 stages
Portland limestone is quite resistant to erosion by the sea. However, the layers behind are less resistant. Any breach in the Portland limestone can expose the weaker rocks behind to coastal erosion, and particularly to hydraulic action. In hydraulic action, air trapped in cracks on a rock face is compressed when a wave breaks, the trapped air is compressed weakening the cliff and causes cracks and holes to get larger.This is what has happened at Stair Hole. Over time, the less resistant Purbeck limestone, and the weak clays have been eroded to form a dramatic inlet. In rough weather, sea water shoots up through the blow holes in the limestone, further weakening the barrier. Eventually, a cove will develop behind the remaining limestone.
Lulworth Cove - A natural harbour on the Dorset coast
Just a few hundred yards from Stair Hole, you can see the natural harbour of Lulworth Cove. It too is tucked away behind the ridge of Portland limestone. It has formed since the last Ice Age, as a result of water power, from a river and the sea.
It began when a river, swollen with water from the melting ice, began to cut a valley. The river eventually breached the barrier of tough Portland stone. Over time, the rising sea also flooded into the valley and began to wear away the weaker rocks behind the Portland stone.
Formation of Lulworth Cove
The Greensand - Chalk Boundary - at Lulworth Cove
If you look carefully at this photo of Lulworth Cove, you can see where the Greensand layer joins the Chalk layer. The Greensand layer is visible just behind the buildings on the edge of the cove.
Fantastic photos by Peter Sells and words by Robert Westwood led you on an aerial journey along the amazing Jurassic Coast.
Durdle Door - Dorset
Durdle Door illustrates a further development where the Portland Limestone has been eroded into stacks, now collapsed to leave stumps, just visible in the waves, and an impressive arch. Eventually the arch will collapse to leave another stack. In the background, you can see the Isle of Portland, which is connected to the mainland by a tombolo: a narrow piece of land connected at both ends.
St Oswald's Bay
St Oswald's is a double bay, next to Durdle Door. Again you can see the remaining stumps of Portland Limestone. If you look at the sea on the upper (more easterly) bay, you will see a brown stain in the water. This is where a large section of the cliff had collapsed into the sea a couple of days before. A section of the coastal path also fell into the sea, so the coastal path has now been re-routed.
This is an active coastline, changing from year to year, as a result of rain, storms, and the actions of the sea.
In January 2014, the 150 million-year-old rock stack known as Pom Pom Rock collapsed during a violent storm. You can read more about the widespread storm damage here.
East Dorset Coast
Swanage is a good base for exploring the Jurassic Coast of southern England
Concordant and Discordant Coastlines
The making of a coastline
The shape of a coastline develops over many thousands of years as a result of wave action and weather pounding the rocks and beaches. Different rocks can be more or less resistant to this energetic process resulting in the construction of headlands, bays, caves, and coves.
More information about the Jurassic Coast
- The Jurassic Coast
The Dorset and East Devon Coast World Heritage Site is England's first natural World Heritage Site - it is known as The Jurassic Coast. It covers 95 miles of truly stunning coastline from East Devon to Dorset, with rocks recording 185 million years o
- St Oswald's Bay
More about St Oswald's Bay, Dorset
- Lulworth Cove
More about Lulworth Cove, on the Jurassic Coast World Heritage Site in Dorset, southern England.
- Durdle Door
More about Durdle Door, Dorset
- Jurassic Coast - World Heritage Site
Wikipedia article on the World Heritage Site of the Dorset and East Devon Coast.