The Wem-Bridgemere-Red Rock Fault System is a complex zone of intersecting faults which defines the eastern boundary of the

Cheshire Basin The Cheshire Basin is a late Palaeozoic and Mesozoic sedimentary basin extending under most of the county of Cheshire in northwest England. It extends northwards into the Manchester area and south into Shropshire. The basin possesses something of t ...

, a deep

sedimentary basin Sedimentary basins are region-scale depressions of the Earth's crust where subsidence has occurred and a thick sequence of sediments have accumulated to form a large three-dimensional body of sedimentary rock. They form when long-term subsidence ...

in the northwest of

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe ...

and extending south into the northern

Midlands The Midlands (also referred to as Central England) are a part of England that broadly correspond to the Mercia, Kingdom of Mercia of the Early Middle Ages, bordered by Wales, Northern England and Southern England. The Midlands were important in ...

. It includes the Red Rock Fault, Bridgemere Fault and Wem Fault and reaches from

Shropshire Shropshire (; alternatively Salop; abbreviated in print only as Shrops; demonym Salopian ) is a landlocked historic county in the West Midlands region of England. It is bordered by Wales to the west and the English counties of Cheshire to ...

through eastern

Cheshire Cheshire ( ) is a ceremonial and historic county in North West England, bordered by Wales to the west, Merseyside and Greater Manchester to the north, Derbyshire to the east, and Staffordshire and Shropshire to the south. Cheshire's coun ...

to southeast

Lancashire Lancashire ( , ; abbreviated Lancs) is the name of a Historic counties of England, historic county, Ceremonial County, ceremonial county, and non-metropolitan county in North West England. The boundaries of these three areas differ significa ...

.Plant et al. (eds) 1999 ''The Cheshire Basin: basin evolution , fluid movement and mineral resources in a Permo-Triassic rift setting''. British Geological Survey At Norbury Brook,

Poynton Poynton is a town in Cheshire, England, on the easternmost fringe of the Cheshire Plain, south-east of Manchester, north of Macclesfield and south of Stockport. Poynton has formed part of the Cheshire East unitary authority since the aboli ...

, on the border of Cheshire and

Greater Manchester Greater Manchester is a metropolitan county and combined authority area in North West England, with a population of 2.8 million; comprising ten metropolitan boroughs: Manchester, Salford, Bolton, Bury, Oldham, Rochdale, Stockport, Tamesid ...

, the Millstone Grit of the

Pennines The Pennines (), also known as the Pennine Chain or Pennine Hills, are a range of uplands running between three regions of Northern England: North West England on the west, North East England and Yorkshire and the Humber on the east. Commonly ...

makes a downfall to be covered to the west by the glacial tills of the

Cheshire Plain The Cheshire Plain is a relatively flat expanse of lowland within the county of Cheshire in North West England but extending south into Shropshire. It extends from the Mersey Valley in the north to the Shropshire Hills in the south, bounded by ...

, formed by the retreating

ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gre ...

glaciers. To the east of the fault there are the

coal measures In lithostratigraphy, the coal measures are the coal-bearing part of the Upper Carboniferous System. In the United Kingdom, the Coal Measures Group consists of the Upper Coal Measures Formation, the Middle Coal Measures Formation and the Lower Co ...

of the Carboniferous period, which unlike those in the

Lancashire Coalfield The Lancashire Coalfield in North West England was an important British coalfield. Its coal seams were formed from the vegetation of tropical swampy forests in the Carboniferous period over 300 million years ago. The Romans may have been the f ...

are missing the top layers. Here there are outcrops of the Middle Coal Measures.

Coal Coal is a combustible black or brownish-black sedimentary rock, formed as stratum, rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen ...

from these strata, particularly the ''Four Foot mine'' (or seam), the ''Five Foot mine'' and the ''Accommodation mine'' was

extract An extract is a substance made by extracting a part of a raw material, often by using a solvent such as ethanol, oil or water. Extracts may be sold as tinctures, absolutes or in powder form. The aromatic principles of many spices, nuts ...

ed in the nineteenth and early twentieth century. The two masses are still moving and regularly generate small

earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...

s usually less than 3.0 on the

Richter Scale The Richter scale —also called the Richter magnitude scale, Richter's magnitude scale, and the Gutenberg–Richter scale—is a measure of the strength of earthquakes, developed by Charles Francis Richter and presented in his landmark 1935 p ...

along its length. In 2002, there was a swarm of over 110 earthquakes felt in Manchester, close to the fault, over a period of a few months. The strongest was 3.9, on Thursday, 24 October 2002 at 08:25 GMT.

References

Bibliography

{{cite book, last=Brenchley, first=P. J., author2=Peter Franklin Rawson , title=The geology of England and Wales , publisher=Geological Society, year=2006, isbn=1-86239-200-5, url=https://books.google.com/books?id=-6gqvAbdS-MC&dq=Red+rock+fault&pg=PA271 Geology of England Seismic faults of the United Kingdom Geology of Cheshire