Somerset – Based Events (England)

What’s here? 

• Superb exposures of fault systems within the Triassic/Lower Jurassic of the East Bristol Channel and Central Somerset Basins.
• 3D seismic scale fault systems including a variety of fault geometries, fabrics and networks.
• Supported by materials on stress, strain and fracture development as well as fault seal and trap analysis.

Geological Themes

Fault systems exposed on the North Somerset foreshores deform Triassic to Lower Jurassic stratigraphy and are located on the southern margin of the Mesozoic to Tertiary, E-W and NW-SE trending East Bristol Channel and Central Somerset Basins.  These Basins link the Main Bristol Channel Basin with the western part of the Wessex Basin located to the east.  The Triassic strata comprise a series of red mudstones and siltstones laid down in playa lake settings.  These are overlain by lacustrine and marine gypsiferous marls, siltstones, sandstones and dolomites of the Blue Anchor Series. Rhaetian marine mudstones and finally marine marls and limestones of the Blue Lias Formation of the Lower Jurassic complete the transgressive sequence.

Excellent 3D examples of extensional fault systems are exposed in the cliffs and on the foreshore at Kilve in North Somerset along the southern margin of the Bristol Channel.  Extensional faults range from a few metres to several hundred metres in strike-lengths and occur in dark coloured shales and interbedded limestones.

Extensional and inverted fault systems are also exposed in the cliffs and on the foreshore at Watchet in North Somerset along the southern margin of the Bristol Channel.  Inverted Upper Jurassic extensional faults juxtapose grey Lower Jurassic (Lower Lias) shales and interbedded limestones against the red Upper Triassic Mercia mudstones.