Lecture: My House Fell in a Hole! Problems with Soluble Rocks
Speaker:
Entry Fee
Members: Free
Visitors: £5.00
Date and Time
19:30 -
Location
Bath Royal Literary and Scientific Institution, 16-18 Queen Square, Bath BA1 2HN
Lecture Description
Gypsum (hydrated Calcium Sulphate CaSO4.2H2O, the raw material for plaster) is widespread throughout the world, but it dissolves so rapidly that it poses a threat to any development that encounters it. More than one metre of gypsum per annum can be easily dissolved by moderate river action on natural exposures. Where this dissolution occurs underground at similar rates, caves can develop, expand rapidly and suddenly collapse. Such caves occur in the Permian rocks of the Vale of Eden, Cumbria and beneath Ripon, North Yorkshire.
Under suitable groundwater flow conditions caves in gypsum can enlarge at a rapid rate resulting in large chambers. Collapse of these chambers produces breccia pipes which propagate through the overlying strata to break through at the surface and form subsidence hollows. Subsidence problems at Ripon (UK) are due to this phenomenon and periodically affect local properties. By this mechanism holes, commonly up to 20m deep and 40m or more across, continue to appear suddenly in gypsiferous terranes throughout the world.
Attending via Zoom
This is a hybrid meeting: you can attend in person or join online via Zoom.
Bath Geological Society Members: Free of charge. Joining instructions and the Zoom link are sent to members by email prior to the lecture.
Visitors & Non-Members: (including members of the Geologists' Association and affiliated societies) Please book via Eventbrite to receive Zoom access (see the Entry Fee details above).
How to join: Click the Zoom link provided in your email or Eventbrite confirmation. You can join using the Zoom desktop or mobile app, or directly via your web browser without installing any software. The virtual waiting room opens approximately 15 minutes before the scheduled start time, and attendees will be admitted before the talk commences.
For any queries about joining online, please contact [email protected].