Effingham Tertiaries Operational Catchment
Water bodies
There are 1 water bodies in this operational catchment.
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About
The ‘Effingham Tertiaries’ groundwater body (GWB) refers to groundwater residing in the sands and sandstones of the Lambeth Group and Thanet Sands between Farnham in the west and Epsom in the north-east. The Lambeth Group, formerly known as the Woolwich and Reading Beds, comprises about 30m of mainly clay strata but also includes sandstones classified as Secondary aquifers. Its stratigraphic position in this part of Surrey is between the Upper Cretaceous Chalk (Thanet Sands where present) and the London Clay. The W - ENE strike of the strata, as they dip into the London Basin, forms a ribbon-like outcrop of about 300m width north of the Hog’s Back and North Downs chalk escarpment. The GWB is soon confined beneath the London Clay to the north, along with the ‘Guildford Chalk’ GWB, with which it could easily be joined. To the north-east, it lies above the ‘Dorking Chalk’ GWB and thereafter becomes the ‘Bromley Tertiaries’ GWB, incorporating a thicker Thanet Sands aquifer. Similarly, there is a western boundary, so that from Farnham westwards the GWB becomes the ‘Old Basing Tertiaries’.
