Dorset day four, 18 Oct 2010

Day four Itinerary

 

10:00 – 13:00

Portland Bill

13:00 – 14:00

Lunch at the Portland Heights Hotel

In-depth information from the rest of the web

For the geology of Portland, click here.

Write up of day four

 

After the beautiful weather of the previous two days Monday dawned with a light drizzle - which cleared by the time we set off for the Chesil Beach and Portland.

We saw the extensive flood alleviation measures to try to prevent a re-occurrence of the floods of the 1970’s, these included culverts to drain the sea water which seeps through the Chesil Bank. As we climbed to the top of the bank, which is surprisingly steep, we noted the larger size of the pebbles which long-shore drift grade from fine grit in the west to the large pebbles at Portland. Chesil is some 28 kilometres long and has probably existed for 6000 years. It is moving landward and may eventually cause the Fleet Lagoon to disappear; the lagoon at the moment is an important nature reserve sustaining fresh and saltwater species and a diverse collection of water fowl. Steps to try to contain the movement of the bank include the installation of concrete ridges at the apex which although covered in pebbles are observable, especially from the higher points of the island of Portland.

We resumed our journey through the Victorian settlement of Fortuneswell to visit the quarries, Albion Stone, Bowers, Suck Thumb and King Barrow. At Albion, a working quarry, the Purbeck beds and base material is removed before quarrying the Portland stone. Machinery from Italy (used there to cut marble) is employed to make vertical cuts in the stone, stainless steel bags are then inserted into the cuts and inflated to sever the required block. Each block is numbered and catalogued and can command a price of £500 per cubic metre. At Bowers Quarry, another active site, we observed open quarrying and saw the entrances leading to the stone mines. In the storage area we were able to see trace fossils and ripple marks. St. George’s Church, adjacent to Bowers was built in the 18th century, apparently on one of the few sites on the island where sufficient soil depth allowed graves to be dug.

In SuckThumb quarry large blocks of stone contained casts of the footprints of a three toed dinosaur. King Barrow Quarry was mostly hand worked and is now a nature reserve having ceased production in the 1890’s. Unlike today, there was no requirement then to backfill and landscape. The quarry has now regenerated naturally and hosts flora and fauna specific to the limestone soil, there is some scrub management. On the rim of the quarry we saw more of the fossil forest which may have extended across the island and possibly through to Lulworth.

The grounds of the Heights Hotel, our lunch venue, contained more interesting evidence of the fossil heritage; large ammonites were set into the walls and a nine foot piece of fossilised wood stood near the entrance.

Lunch was good and a companionable way to end our four day field trip. All thanks go to our guide Alan Holiday, and to our team of very expert organisers, amongst whom Jim and Alan feature strongly. I am sure we all enjoyed the experience and look forward to further trips.

Pictures from day four

 

01_Chesil_Beach.jpg

Chesil Beach, as seen from Portland.

 

02_Group_at_quarry.jpg

The group at Albion Stone Quarry.

 

03_Quarry.jpg

Albion Stone Quarry.

 

04_Titanites.jpg

Titanites ammonite fossil in Purbeck limestone.
Albion Stone Quarry.

 

05_Ripple_Marks.jpg

Ripple marks. Albion Stone Quarry.

 

06_Dinosaur_footprint.jpg

Dinosaur footprint, SuckThumb Quarry.

 

07_Fossil_Forest.jpg

Siliconised tree stumps in the fossil forest.
King Barrow Quarry.

 

08_Ammonite.jpg

Ammonite. Portland Heights Hotel.

 

09_Fossil_wood.jpg

The group looking at a piece of fossilised wood.
Portland Heights Hotel.

 

Return to home page.