Old Harry Rocks
The Forming of The Old Harry Rock
The chalk of Old Harry Rocks used to be part of a long stretch of chalk between Purbeck and the Isle of Wight, but remained as a headland after large parts of this seam were eroded away. As the headland suffered Hydraulic action (a process in which air and water is forced into small cracks by the force of the sea, resulting in enlarging cracks), first caves, then arches, formed. The tops of the arches collapsed after being weakened by rainfall and wind, leaving disconnected stacks. One of these stacks is known as Old Harry. Old Harry's Wife was another stack which was eroded through corrosion and abrasion, until the bottom was so weak the top fell away, leaving a stump. Hydraulic action is the main cause of erosion in this case.
The Jurassic Coast stretches over a distance of 158 kilometres (98.176648373 mi), from Orcombe Point near Exmouth, in the west, to just beyond the great chalk headland of Ballard Down and Old Harry Rocks here in the east. The coastal exposures along the coastline comprise a continuous sequence of Triassic, Jurassic and Cretaceous rock formations spanning approximately 185 million years of the Earth's history. The rock layers along the Jurassic Coast are tilted towards the east. The oldest part of the coast is found at its west end, while progressively younger rocks form the cliffs here to the east. Old Harry Rocks mark the most easterly point of the Jurassic Coast, a UNESCO World Heritage Site.
The downlands of Ballard Down are formed of chalk with some bands of flint, and were formed approximately 65 million years ago. The bands of stone have been gradually eroded over the centuries, some of the earlier stacks having fallen (Old Harry's original wife fell in 1509), while new ones have been formed by the breaching of narrow isthmuses. Across the water to the east The Needles on the Isle of Wight are usually visible. These are also part of the same chalk band and only a few thousand years ago were connected to Ballard Down.
To form the stacks, the sea gradually eroded along the joints and bedding planes where the softer chalk meets harder bedrock of the rock formations to create a cave. This eventually eroded right through to create an arch. The arch subsequently collapsed to leave the stacks of Old Harry and his wife, No Man's Land and the gap of St Lucas' Leap. The large outcrop of rock at the end of the cliffs is often referred to as "No Man's Land".
Old Harry is formed by erosion processes, which will eventually remove the stack, whilst new stacks develop. Some people desire to preserve the rocks and protect them from the erosive processes that formed Old Harry. A team headed by Dr C. P. Buckle of the University of Strasbourg is exploring this. This research is in stark contrast with the National Trust who own the stacks in perpetuity. The Trust's experience in looking after the coast has found that "working with natural processes is the most sustainable approach".
There are two stories about the naming of the rocks. One legend says that the Devil (traditionally known euphemistically as "Old Harry") had a sleep on the rocks.
Another local legend says that the rocks were named after Harry Paye, the infamous Poole pirate, who stored his contraband nearby. These could be linked as Harry Paye could have been considered as the devil and could well have slept on these rocks.
- Media related to Old Harry Rocks at Wikimedia Commons
- List of places on the Jurassic Park
- The Needles
- The Jurassic Park Trust (2003). A Walk Through Time, the Official Guide to the Jurassic Park. Coastal Publishing. ISBN 978-0-9544845-0-7.
- Old Harry Rocks - The end of the story Jurassic Coast homepage. Retrieved 2010-11-16