Presentation by Professor Simon Haslett at the University of the Third Age Mendip Hills Study Day at Draycott, Somerset, on 1st March 2012. Simon Haslett is Professor of Physical Geography and Associate Pro Vice-Chancellor at the University of Wales. The talk is based on extracts from S. K. Haslett (2010) Somerset Landscapes: Geology and Landforms. Blackbarn Books. Available from: https://sites.google.com/site/blackbarnbooks/publications/somerset-landscapes-geology-and-landforms

1. The Mendip Hills:
Geology and Landforms
Professor Simon Haslett
Presented at the University of the Third Age
Mendip Hills Study Day, Draycott, 1st March 2012

2. Somerset Landscapes

3. Somerset Geology
From: S. K. Haslett (2010) Somerset Landscapes: Geology and Landforms. Blackbarn Books.

4. Geological Timescale
From: S. K. Haslett (2010) Somerset Landscapes: Geology and Landforms. Blackbarn Books.

5. Palaeozoic Geology of Mendip
From: S. K. Haslett (2010) Somerset Landscapes: Geology and Landforms. Blackbarn Books.

6. Tectonic setting
Variscan Orogeny (also known as the Hercynian or Armorican
Orogeny).
From: S. K. Haslett (2010) Somerset Landscapes: Geology and Landforms. Blackbarn Books.

7. Mendip Anticline
From: S. K. Haslett (2010) Somerset
Landscapes: Geology and Landforms.
Blackbarn Books.

8. Chew Valley Syncline

9. Silurian Fossils
e.g. Beacon Hill
• Deposited
in a shallow
marine
setting.
• Warm
subtropical
waters.
• Continental
drift
implication.
From: S. K. Haslett (2010) Somerset Landscapes: Geology and Landforms. Blackbarn Books.

10. Old Red Sandstone
• Deposited in a delta setting within
an arid environment.
• Implications for continental drift.
From: S. K. Haslett (2010) Somerset
Landscapes: Geology and Landforms.
Blackbarn Books.

11. From: S. K. Haslett (2010) Somerset
Landscapes: Geology and Landforms.
Blackbarn Books.
• Deposited in a
shallow marine
setting.
• Warm tropical
waters.
• Chemical
precipitation
and
dissolution.
• Continental
drift
implications.
Carboniferous Limestone

12. Western Mendip
Rounded profile to the Mendip Hills.
Flat core to steep flanks.
Little surface drainage.
From: S. K. Haslett (2010) Somerset
Landscapes: Geology and Landforms.
Blackbarn Books. Shute Shelve Hill

13. Axe Valley and Inliers
• Flanks of the Mendip Hills – an ancient feature.
• Mendip inliers can be seen.
• Jurassic beaches occur on its flanks.
• Jurassic sediments infill fissures in
Carboniferous Limestone. From: S. K. Haslett (2010) Somerset
Landscapes: Geology and Landforms.
Blackbarn Books.

14. Knowle Hill Inlier
• Indicate southern limit of Mendip Hills.
• Older Carboniferous surrounded by Jurassic.
• Clues to the age of the Axe and other valleys.
• Complex landscape evolution and history.
From: S. K. Haslett (2010) Somerset
Landscapes: Geology and Landforms.
Blackbarn Books.

15. Permo-Trias
Dolomitic Conglomerate
River Sheppey, Croscombe
From: S. K. Haslett (2010) Somerset Landscapes: Geology and Landforms. Blackbarn Books.

16. Mining landscape at Priddy
• Hot water rising from
earth’s interior guided by
the anticline structure.
• Introduced hydrothermal
minerals.
• First phase – Carboniferous
• Economically important:
lead, zinc and iron ores.
From: S. K. Haslett (2010) Somerset Landscapes: Geology and Landforms. Blackbarn Books.

17. Jurassic on Mendip Plateau
• Second phase – silica-rich water.
• Silicified Jurassic Harptree Beds on top of the
centre of the Mendip Hills.
From: S. K. Haslett (2010) Somerset Landscapes: Geology and Landforms. Blackbarn Books.

18. Brean Down
• Where the Mendip Hills meet the sea.
• Steepholm and Flatholm in Bristol Channel.
• Extends to South Wales – rim of the coalfield
syncline.
From: S. K. Haslett (2010) Somerset
Landscapes: Geology and Landforms.
Blackbarn Books.

19. Thank you
• Economic exploitation.
• Limestone quarrying.
• E.g. Torr Quarry
Photo by Dr John Robb.
• Further Reading: