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The shrink–swell capacity of soils refers to the extent certain clay minerals will expand when wet and retract when dry. Soil with a high shrink–swell capacity is problematic and is known as shrink–swell soil, or expansive soil . [ 1 ]
The London Clay Formation is a marine geological formation of Ypresian (early Eocene Epoch, c. 54-50 million years ago) [1] age which crops out in the southeast of England. The London Clay is well known for its fossil content. The fossils from the lower Eocene rocks indicate a moderately warm climate, the tropical or subtropical flora.
In places, there are deposits of brickearth, which is a mixture of clay and sand that has supported London's long-standing brick-making industry. On top of these natural layers are the deposits of hundreds of years of human occupation. In the oldest parts the City of London and the City of Westminster this layer can be up to 6 metres deep. [5]
At the present time, Scotland is continuing to rise as a result of the weight of Devensian ice being lifted. Southern and eastern England is sinking, generally estimated at 1 mm (1 ⁄ 25 inch) per year, with the London area sinking at double the speed partly due to the continuing compaction of the recent clay deposits.
The majority of the rest of England and Wales north of the Variscan Front are considered to constitute the Avalon composite terrane. Central to this composite terrane is the triangular-shaped Midlands Microcraton ; within it, the north–south aligned Malvern line (or 'Malvern lineament') divides the Wrekin terrane in the west from the ...
The geology of England is mainly sedimentary. The youngest rocks are in the south east around London , progressing in age in a north westerly direction. [ 1 ] The Tees–Exe line marks the division between younger, softer and low-lying rocks in the south east and the generally older and harder rocks of the north and west which give rise to ...
A swell in geology is a domed area of considerable areal extent. [1] According to Leser, it is also called a sill (geology), and is a gently arched landform of various orders of size in topographic, sub-glacial or sub-hydric geology. It may be as small as a rock formation in a river or may assume continental scale. [2]
Column 4 indicates on which sheet, if any, of the British Geological Survey's 1:50,000 / 1" scale geological map series of England and Wales, the fault is shown and named (either on map/s or cross-section/s or both). A handful of BGS maps at other scales are listed too.