Category:12. East Anglia and adjoining areas: Difference between revisions

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This account provides a broad perspective of the geology of East Anglia and adjoining areas, which includes the counties of Norfolk, Suffolk, Cambridgeshire and parts of Lincolnshire and Bedfordshire. Figure 1 provides a geological sketch map of this region showing the rock types occurring in relation to the major towns and cities. East Anglia’s relatively flat and rolling landscape, mainly less than 100 m above sea-level, provides a rich agricultural setting and contains an interesting geological story. This account sketches out the geology to a depth of at least a kilometre and summarises the current and historical use of the geological resources in the region.
[[Image:P902251.jpg|thumb|400px|Geological map and key showing the range and distribution of different bedrock types in East Anglia and adjoining areas. The extent of The East Anglia and adjoining areas is identified on the inset map of the United Kingdom. P902251.]]
This account provides a broad perspective of the geology of East Anglia and adjoining areas, which includes the counties of Norfolk, Suffolk, Cambridgeshire and parts of Lincolnshire and Bedfordshire. '''Figure P902251''' provides a geological sketch map of this region showing the rock types occurring in relation to the major towns and cities. East Anglia’s relatively flat and rolling landscape, mainly less than 100 m above sea level, provides a rich agricultural setting and contains an interesting geological story. This account sketches out the geology to a depth of at least a kilometre and summarises the current and historical use of the geological resources in the region.


The surface geology of the region is known from quarries, coastal cliffs and shallow boreholes. At greater depths, below about 250 m, our direct knowledge comes from about 50 deep boreholes spread fairly evenly across the region. The deepest of these go down over a kilometre, and most were drilled to explore for water or coal. Geophysical surveys, carried out on land or by low flying aircraft, reveal patterns of the Earth’s gravity and magnetic field, and these also give us clues as to the deeper geology of the region. East Anglia is not known to contain oil, gas, coal or metal resources at depth, and there has been no deep mining within the region. As a result detailed information on the deep geology is sparse.
The surface geology of the region is known from quarries, coastal cliffs and shallow boreholes. At greater depths, below about 250 m, our direct knowledge comes from about 50 deep boreholes spread fairly evenly across the region. The deepest of these go down over a kilometre, and most were drilled to explore for water or coal. Geophysical surveys, carried out on land or by low flying aircraft, reveal patterns of the Earth’s gravity and magnetic field, and these also give us clues as to the deeper geology of the region. East Anglia is not known to contain oil, gas, coal or metal resources at depth, and there has been no deep mining within the region. As a result detailed information on the deep geology is sparse.


 
[[Category:Regional Geology overview | 12]]
 
[[Category:Geological_regions_of_England | ]]
 
 
 
 
==North Norfolk==
North Norfolk can broadly be equated with an area north of a line drawn from Kings Lynn through Norwich to Great Yarmouth; the other principal towns in this area include Hunstanton, Fakenham, Aylsham, North Walsham and Cromer The coastline here is dominated by low cliffs (Figure 6) with intervening stretches of sand spits, marshes and dunes.
 
===Sedimentary Bedrock===
In this area there is a thick sequence of sedimentary bedrock layers which exceeds 1000 m in total between Cromer and Great Yarmouth in northeast Norfolk. As a result, the top of the underlying basement rocks is well below 1 km depth in that part of the area.
The same easterly-tilted younger sedimentary bedrock layers described from the rest of Norfolk and Suffolk continue through this area but are even thicker, reaching over 500 m in parts of northeast Norfolk. They comprise interbedded sandstones and mudstones including the Gault Clay overlain by Chalk, which in places in the east is covered by further sands and clays. The lower sandstones and clays are thickest where they are exposed at the surface between Kings Lynn and Hunstanton reaching up to 75m, however they thin out quickly when traced eastwards beneath the Chalk. The Chalk locally exceeds 450 m in thickness with the overlying sand and clay layers reaching 80 m thick but restricted to the fringes of the east Norfolk coast.
 
The further sedimentary bedrock layers described from the Fenland also continue eastwards beneath the Chalk and are not pinched out as they are to the south. Instead, they form a thickening sequence of layers to the east along the Norfolk coast.
 
Between Wells next the Sea and Great Yarmouth, Older Sedimentary Bedrock layers are also present at depth. These include sandstones, mudstones, and limestones of the Carboniferous Limestone and the Coal Measures. Elsewhere in Britain some of these layers are encountered nearer the surface and form important aquifers, however little is known about their water content beneath the North Norfolk coast and evidence from similar geological settings elsewhere in the UK suggest that it is likely to be saline.
 
===Basement rocks===
The basement rocks in this area are similar to those encountered below the other areas with grey mudstones and sandstones which have been changed by high temperatures and pressures in the long time since they were formed; thin layers of volcanic lavas have also been found in some boreholes. There may be a single granite intrusion in the area north of Fakenham based on the gravity and magnetic data, although other possible interpretations have also been suggested.
 
 
[[Category:Regional Geology | 12]]

Latest revision as of 09:36, 19 April 2016

Geological map and key showing the range and distribution of different bedrock types in East Anglia and adjoining areas. The extent of The East Anglia and adjoining areas is identified on the inset map of the United Kingdom. P902251.

This account provides a broad perspective of the geology of East Anglia and adjoining areas, which includes the counties of Norfolk, Suffolk, Cambridgeshire and parts of Lincolnshire and Bedfordshire. Figure P902251 provides a geological sketch map of this region showing the rock types occurring in relation to the major towns and cities. East Anglia’s relatively flat and rolling landscape, mainly less than 100 m above sea level, provides a rich agricultural setting and contains an interesting geological story. This account sketches out the geology to a depth of at least a kilometre and summarises the current and historical use of the geological resources in the region.

The surface geology of the region is known from quarries, coastal cliffs and shallow boreholes. At greater depths, below about 250 m, our direct knowledge comes from about 50 deep boreholes spread fairly evenly across the region. The deepest of these go down over a kilometre, and most were drilled to explore for water or coal. Geophysical surveys, carried out on land or by low flying aircraft, reveal patterns of the Earth’s gravity and magnetic field, and these also give us clues as to the deeper geology of the region. East Anglia is not known to contain oil, gas, coal or metal resources at depth, and there has been no deep mining within the region. As a result detailed information on the deep geology is sparse.

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