Groundwater in Jurassic carbonates

The Lincolnshire Limestone is an important regional aquifer. Pumping stations at Bourne and other locations along the eastern edge of the Fens supply water to a large population in South Lincolnshire. Karst permeability development and rapid groundwater flow raise issues of groundwater source protection, one of themes of this excursion. A second theme concerns the influence of landscape development on the present hydrogeology. Glacial erosion during the Middle Pleistocene re-oriented river patterns and changed the aquifer’s boundary conditions. Some elements of the modern groundwater flow pattern may be controlled by karstic permeability inherited from pre-glacial conditions, whereas other flow directions are a response to the aquifer’s current boundary conditions. Extremely high permeability is an important feature in part of the confined zone of the present-day aquifer and the processes that may have produced this are a third theme of the excursion. The sites to be visited will demonstrate the rapid groundwater flow paths that have been proved by water tracing, whereas the topography and landscape history will be illustrated by views during a circular tour from the aquifer outcrop to the edge of the Fenland basin and back. Quarry exposures will be used to show the karstification of the limestone, both at outcrop and beneath a cover of mudrock.