The impact of urban groundwater upon surface water - eTheses ...

STUDY SETTING
problematic and Horton (1974) proposed a subdivision based on four lithological types
summarised as follows (Knipe et al, 1993).
1. Glacial till deposited beneath the ice sheets and retreating glaciers. The unit consists of
boulder clay and unbedded drift comprising unsorted rock debris in a sandy clay matrix.
2. Glacio-lacustrine deposits formed in ice-dammed lakes. The unit comprises clay, silt, fine-
grained sand and peat.
3. Glacio-fluvial deposits derived from meltwaters flowing from or beneath the glaciers.
4. Interglacial deposits formed in shallow lakes and marshes between periods of ice advance.
The unit comprises humic silt and clay with some peat beds.
The glacial deposits cover a buried landscape significantly different from that of the present
and including several buried valley systems with sand and gravel fill running on different
courses to the current drainage pattern. The distribution of the drift types is highly variable
across the region but in general the boulder clay is generally found on the higher ground and
lining the sides and base of the main depressions (Knipe et al., 1993).
Postglacial deposits in the district are primarily products of the erosion of earlier glacigenic
deposits and subsequent deposition under fluvial and lacustrine conditions. Alluvial deposits
comprising sands, gravels and clays are found in the valley bottoms of all the current water
courses. Flood plain deposits up to 1 km in width occur in the Tame Valley and two
additional stages of river terrace deposition have been identified that predate the recent
alluvium.
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