Isle of Wight geology - September 2007

In September 2007 I led an “enthusiastic” group of my Stockport U3A geology group on a five day trip to the Isle of Wight. The Isle of Wight can best be described as a Geological Odyssey with the cliffs of the island as windows into lost worlds through which you can view the dinosaurs, ancient seas and frozen Ice Age landscapes. I wish to pay tribute to Dr Fred Broadhurst and Dr Paul Selden who, having led their own trip to the Isle of Wight at an earlier date, kindly gave me permission to refer to their field trip notes enabling me to lead my amateur group around the most important sites.

The island’s odyssey began about 120 million years ago, rocks (known as the Wealden Group), dating between that time and about 110 million years ago, can be seen in the cliffs along the south west coast and at Yaverland. From these rocks come the bones and footprints of dinosaurs. Fossil hunting near Atherfield Point yields a tremendous variety of nautiloids and dinosaur bones, most of which are housed and displayed in the Fossil shop at Blackgang Chine run by Martin Simpson. Some of our members may remember Martin who was once a member of the MGA.

He describes himself as an enthusiastic palaeontologist living in Whitwell and sharing his home with over 36,000 fossils! If you are ever visiting the Isle of Wight call Martin at the Fossil shop on 01983 730233. Martin also runs the Fossil Farm at nearby Brighstone and welcomed visitors (including us) and showed us round his fascinating display of fossils in the converted barn. (Tel 01983 740 844). Some time ago, before Martin took over, I visited the farm (as it was then) to view a dinosaur which had been exposed in the cliff face by erosion and the farmer on whose land it was had dug it out and the students from Southampton University were painstakingly cleaning it up. It has since been removed to the Dinosaur Isle Museum at Yaverland in the south east of the island.

By 110 million years ago, sea levels began to rise and the low lying land of the dinosaurs was lost below a warm shallow sea. This sea swarmed with ammonites, lobsters and oysters and the rocks formed from layers of sandstone & mud became known as the Lower Greensand, to be seen at Blackgang.

At about 94 million years ago the sea deepened and black muds were laid down to become known as the Gault Clay. Lying on top of this is the Upper Greensand and the Chalk.

At about 65 million years ago the Cretaceous world came to an end and the Palaeogene rocks were formed, the remains of which our group were able to view at Alum Bay, adjacent to the Needles. Here at about 35 million years ago we were able to see the folded and highly colourful rocks comprising glauconitic muds (aluminium/magnesium/iron rich micas) coarsening upwards into tidal sands with occasional lignite beds.

Alum Bay

Our other major visit was to Yaverland east of Sandown where they have an excellent “hands on” Dinosaur Isle teaching museum of dinosaurs – well worth a visit. Just east of the museum we were able to examine close-up the Wessex formation (dinosaur bones) and the overlying Vectis formation which are a series of dark grey mudstones absolutely packed with gastropods such as Viviparus.

The Vectis Formation

If any group is thinking of going on a geology trip to the Isle of Wight we found it convenient to base ourselves in Shanklin at a very obliging hotel on the cliff top and with an indoor swimming pool and good grub!

Shanklin Chine was the defile down which the Pluto pipe line was channelled before crossing over to the Normandy beaches.

John Price