Jurassic Coast History - part one

Pulford Publicity’s Cause of the Year: Clean Jurassic Coast

By Roy Beal

The Jurassic Coast is a 95- mile wonder of the natural world and is the only place on earth where there is evidence from all three periods of the Mesozoic era in one place.

The vividly coloured sandstone cliffs predominantly found between Exmouth and Lyme Regis come from the Triassic period. It’s unusual to find any fossils along this stretch of coast, but if you are fortunate to stumble upon one, it’s likely to be between 201 and 252 million years old!

The reddish cliff colour we see today is thanks to the land’s iron content, which has since oxidised (rusted). The sandstone is soft and coastal erosion has created some fabulous features, such as the stacks visible at Ladram Bay.

The Jurassic era rock strata is blue-grey in colour and has the most exciting fossils found along the Jurassic Coast. At Charmouth and Chapmans Pool, fossils are easily found with a gentle stroll at low tide. The undercliffs between Seaton and Lyme Regis also show a wonderful selection of fossils, as well as a fascinating view of some spectacular geology from this time.

Sealife was in abundance during this period, the climate perfect for the evolution of predators such as ichthyosaurs and ammonites – the symbol for this World Heritage Site. We also have this period to thank for the advent of petroleum-based production, aka fossil fuels.

After about 56 million years, we entered the Cretaceous period, which lasted 79 million years. In this era, the chalk cliffs we see around Beer, Seaton and at the other end of the Jurassic Coast at Old Harry Rocks were formed.

Bees and other insects appeared during Cretaceous times. Plant and tree life started to spread. The chalk cliffs were formed from a type of algae that was rife in the Cretaceous seas called Coccoliths.

This period ended with mass extinction events, possibly from asteroid impacts and volcanic activity. Another school of thought believes it was a gradual shift in climate and sea levels.

Throughout these periods, the land moved, thus creating today’s coastline. At a great ‘fault’ at Seaton Hole, one can see a transition between the Triassic and Cretaceous. The Jurassic period appears to be missing here, although just a mile or so to the east, it reappears. Our planet is forever changing. Humans have only been here for a very short time – the earliest Homo Sapien remains have only been dated to 200,000 years old, whereas the Jurassic Coast is up to 252 million years old.

When you consider how much we have achieved, and destroyed, in the relatively short time we’ve existed, it’s still obvious that we are just the merest speck of dust on the planetary clock.

Humbling isn’t it?