Events & Courses

Online Training: Geohazards - Evaporite Hazard - Mining and Dissolution by Salt Mining with Dr. Anthony Cooper.

Start time: 17.00 hrs

Gypsum, anhydrite, salt and sinkholes - investigating and understanding evaporite geology and geohazards. By Dr Anthony Cooper, Honorary Research Associate, British Geological Survey. 

Gypsum is all around us, it is the raw material for wall plaster and plasterboard, salt is used on our tables and roads, but in their original geological settings they are both soluble (karstic) rocks that can cause catastrophic geological hazards. Gypsum dissolution is very rapid and a block about 3m cubed in a river dissolved in about 18 months. Underground it dissolves to form buried karstic cave systems that undergo partial collapse resulting in sinkholes. Salt dissolves incredibly rapidly, about 1000 times faster than gypsum. Natural groundwater flows dissolving these rocks result in sulphate-rich and salt rich springs respectively. Salt spring areas have traditionally been exploited for brine supplying the salt industry, a process that has mimicked the natural dissolution, but at a much faster rate. The results of both natural and induced gypsum and salt dissolution can result in subsidence and sinkholes that can collapse properties, destroy dams and disrupt infrastructure.  Gypsum is CaSO4.2H2O, while anhydrite is the anhydrous form CaSO4. The natural or induced hydration of anhydrite to gypsum is accompanied by considerable expansion that can cause engineering problems for schemes such as tunnels and ground source heat pumps. To understand the geology, sinkhole and subsidence features can be physically mapped, investigated by remote sensing, boreholes and near surface geophysics. Borehole investigations show not only the soluble rocks, but also the residues and breccias left behind after dissolution; these form the records of the “missing geology” the recognition of which has stratigraphical, sedimentological and engineering importance. 

Speaker

Dr Anthony H Cooper FGS, CGeol, EuroGeol 

Dr Cooper has a BSc and PhD from Sheffield University followed by 38 years at the British Geological Survey, as a geological surveyor,  team leader for shallow geohazards and risks, and regional geologist for Yorkshire. Since 2014 he has been Honorary Research Associate at the BGS and an independent consultant. 

He has published widely on evaporite karst (gypsum, anhydrite and salt) sinkholes and geological hazards in the UK and abroad, including research and collaborative projects in the UK, Spain, Germany, Lithuania, Ukraine and China. His publications include the investigation of sinkholes and associated strata using techniques embracing geological mapping, remote sensing, geomorphology, Lidar, geophysics, hydrogeology, GIS, damage surveys, borehole analysis and 3D modeling. He has wide experience of the UK Permian and Triassic evaporitic sequences and has worked with planners, developers and engineers to help them avoid or mitigate geological hazards related to soluble rocks in the UK and offshore.