Events & Courses

Time

Tea/Coffee from 17.15 meeting commences at 18:00

This talk will be followed by an evening lecture organised by the Thames Valley Regional Group of the Geological Society on 'The fossil Ram Sandstone aquifer of Jordan: hydrogeology, depletion and sustainability', commencing at 7.00pm.

First talk (18:00) - Britain's icy past: Implications for ground engineering (Simon Price, BGS and University of Cambridge)

The ability to anticipate vertical and lateral changes in the physical properties and structure of the shallow geological subsurface remains a major challenge for ground engineers. Geological and geotechnical variability in natural engineering soils increases uncertainty in the design, construction and performance of infrastructure assets built on or in the ground.

Ground engineering in mid-latitude lowland landscapes affected by past cyclical glacial and periglacial processes intensifies the challenge of anticipating variability. Quaternary climate-driven events have the potential to change effective stresses and so change the original in-situ state of pre-existing frost-susceptible bedrock and sediments. 

Other geological sources of variability include glacial erosion, glacier-transport and deposition, loading by glacier-ice, ground-ice formation and periglacial weathering. Quaternary depositional and stress history therefore influences fundamental geotechnical behaviour which may change from regional to site-scale, within similar geological layers and may also overprint the depositional and erosional histories of bedrock.

This talk explores geotechnical variability in lowland British tills and bedrock of the Oxford Clay Formation around the margin of a former Middle Pleistocene ice margin of the British Ice Sheet (BIS). The talk will explore variations in index properties, undrained shear strength, stiffness and compressibility and compare them with the spatial distribution of Quaternary Provinces and Domains. The degree to which geotechnical variability can be explained because of glacial and/or periglacial history will be discussed. 

The talk will conclude with discussion of the potential implications for ground investigation, and the selection of geotechnical design parameters.

Second talk (19:00) - The fossil Ram sandstone aquifer of Jordan: hydrogeology, depletion ad sustainability (Andreas N. Charalambous)

The Ram Sandstone is a large transboundary aquifer of Cambro-Ordovician age, shared between Jordan and Saudi Arabia. It is 500 m to >4,000 m thick and stores fossil groundwater 10,000-35,000 years old. Modern recharge is probably insignificant and the aquifer has been in a state of depletion since at least the last humid interludes of 5,000 to 10,000 years ago. Groundwater flows NNW from the outcrop in southern Jordan and northwest Saudi Arabia to the Dead Sea. 

Despite its long residence, the groundwater is generally fresh although radium concentrations exceeding accepted limits have been identified recently. Exploitation in Jordan has been mainly in the Southern Desert, predominantly for irrigation with smaller amounts supplying the coastal city of Aqaba. In 2013 a scheme was completed to supply the capital Amman with 100 million m3/year (~274 Ml/day) for 50 years from a wellfield in the Southern Desert, a distance of ~325 km. 

Being a fossil aquifer, its utilization will reduce the stock available for future generations, but with prudent planning, extractions should be sustainable and depletion may not reach a critical level. However, the Dead Sea thermal springs that have been enjoyed since historical times and the baseflow of deeply incised valleys could be affected.

This event will not be livestreamed or recorded; you will need to attend in person to view the talk.

For further information please contact the event convenor: Chris Coleman, [email protected]