1. Geological Society Events, 2017 Year of Risk
The Geological Society, Burlington House, London
Soluble (karstic) rocks including limestone, gypsum and salt all dissolve underground resulting in cavities and cave systems that may collapse causing sinkholes to form at the surface. Limestone dissolves at a slow rate and is well-known for hosting extensive cave systems.
Gypsum and salt dissolve much faster than limestone and also produce cave systems, but they can evolve on a human timescale rather than a geological one and are seldom seen. As a consequence they pose a geological hazard that can cause sinkholes to develop and rapidly spread. Natural gypsum dissolution has resulted in a severe sinkhole problem affecting the city of Ripon in North Yorkshire, and sinkholes further north such as those at Croft, near Darlington, in County Durham.
These are both places frequented by Lewis Carroll and sinkholes are thought to have inspired the story of Alice in Wonderland. Gypsum dissolution-prone areas can be identified both by the occurrence of sinkholes and the presence of sulphate-rich springs. Salt is highly soluble dissolving in the subsurface to feed saline springs which were called wiches in Medieval times. Consequently, the towns of Droitwich, Northwich and Middlewich are all situated on salt springs.
In these towns salt production utilised the natural springs, then increased brine extraction caused catastrophic subsidence in the surrounding areas. The natural dissolution of soluble rocks continues, but by understanding the controlling mechanisms the worst sinkhole areas can be avoided. In addition, some measures can be put in place to help development in the less sinkhole-prone areas.
Dr Anthony Cooper, (Honorary Research Associate at the British Geological Survey)
The talk will be given twice on the same day, once at 3.00pm and once at 6.00pm – please note that if you would like to attend the talks, the 3pm matinees generally have more availability. The talks will be exactly the same in the afternoon and evening.
Entry to the lectures is free to all, but places are allocated on a ballot basis. To enter the ballot complete the ballot form at www.geolsoc.org.uk/lectureballot. Please note: The ballot for this lecture is not yet open.
Email Olivia Barton-Fisher for more information, or to join the newsletter and receive notification when the ballot opens.
Programme – 3.00pm talk
Programme – 6.00pm talk
2.30pm Tea & Coffee
3.00pm Lecture begins
4.00pm Event ends
Please note that the doors to Burlington House will close at 6.15pm and you will not be able to enter the building after this time
5.30pm Tea & Coffee
6.00pm Lecture begins
7.00pm Short drinks reception
8.00pm Event ends