Eastern England from the Tees to the Wash areas - Geology: Difference between revisions

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* The basement geology, which underlies the bedrock, is over 360 million years old and mainly comprises harder, denser rocks which have been strongly compacted and folded. They include both rocks originally deposited as sediments and others that are products of volcanic activity or formed from the solidification of molten rock below ancient volcanoes.
* The basement geology, which underlies the bedrock, is over 360 million years old and mainly comprises harder, denser rocks which have been strongly compacted and folded. They include both rocks originally deposited as sediments and others that are products of volcanic activity or formed from the solidification of molten rock below ancient volcanoes.


[[Image:P902244.jpg|thumb|left|300px|The distinctive landscape of the North York Moors with hard sedimentary bedrock layers capping the higher ground, and softer mudstones and other sediments forming the valley sides. P902244.]]
[[Image:P9202244.jpg|thumb|left|300px|The distinctive landscape of the North York Moors with hard sedimentary bedrock layers capping the higher ground, and softer mudstones and other sediments forming the valley sides. P9202244.]]
The sedimentary bedrock occurs throughout the region and these rocks have been bent and broken by geological forces so that they are now tilted (generally towards the east), cut by fractures and faults, and injected by small amounts of once molten rock forming igneous intrusions. Weathering and erosion have cut-down into this sequence of tilted layers to reveal the older rocks in the west and the younger rocks in the east. There is a considerable variation in the total thickness of the sedimentary bedrock across this region, ranging from about 500 m in the south to around 4500 m at the Humber and over 6000 m at the Tees.
The sedimentary bedrock occurs throughout the region and these rocks have been bent and broken by geological forces so that they are now tilted (generally towards the east), cut by fractures and faults, and injected by small amounts of once molten rock forming igneous intrusions. Weathering and erosion have cut-down into this sequence of tilted layers to reveal the older rocks in the west and the younger rocks in the east. There is a considerable variation in the total thickness of the sedimentary bedrock across this region, ranging from about 500 m in the south to around 4500 m at the Humber and over 6000 m at the Tees.



Revision as of 13:18, 16 October 2014

Recent surface deposits

Much of the region’s low-lying ground, including the Vale of York, Holderness and the Lincoln Marsh is covered by geological deposits of relatively recent origin, having formed over the last 2 to 3 million years. These ‘superficial deposits’ were laid down by former ice-sheets, lakes, rivers and along the coast that, in geologically recent times, extended inland from its current position to cover the south-eastern part of the region known as The Fens. These deposits range in thickness from a thin veneer on high ground to a maximum of around 100 m where they infill valley-like hollows in the harder rocks beneath. The region’s superficial deposits mainly comprise soft sands, clays, peats, gravels, and boulder clays which are easily eroded, as they have not been deeply buried and consolidated to form strong rocks. These deposits have been quarried in many parts of the region.

Geology at depth

Schematic cross-section through Eastern England. The alignment of the section and key are shown in Figure P902254. P902255.
Schematic cross-section through Eastern England. The alignment of the section and key are shown in Figure P902254. P902256.

Below the superficial deposits, or with just a cover of soil where such deposits are absent, are older rocks which geologists broadly split into two distinct types:

  • The sedimentary bedrock geology is composed of quite hard rocks which were originally deposited a few hundred to tens of millions of years ago as layers of sediments in shallow seas, deserts, vast river systems and swamps in times when Britain lay closer to the Equator and the climate and landscape were very different from those of today.
  • The basement geology, which underlies the bedrock, is over 360 million years old and mainly comprises harder, denser rocks which have been strongly compacted and folded. They include both rocks originally deposited as sediments and others that are products of volcanic activity or formed from the solidification of molten rock below ancient volcanoes.
The distinctive landscape of the North York Moors with hard sedimentary bedrock layers capping the higher ground, and softer mudstones and other sediments forming the valley sides. P9202244.

The sedimentary bedrock occurs throughout the region and these rocks have been bent and broken by geological forces so that they are now tilted (generally towards the east), cut by fractures and faults, and injected by small amounts of once molten rock forming igneous intrusions. Weathering and erosion have cut-down into this sequence of tilted layers to reveal the older rocks in the west and the younger rocks in the east. There is a considerable variation in the total thickness of the sedimentary bedrock across this region, ranging from about 500 m in the south to around 4500 m at the Humber and over 6000 m at the Tees.

The basement rocks are only encountered in a relatively few boreholes located in the south of the region but exploration surveys including geophysical surveys, carried out on land or by low flying aircraft, reveal patterns of the Earth’s gravity and magnetic field and have shown the nature and distribution of these rocks elsewhere. Figures P902255 and P902256. are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variation across the region.

Geology has played a major role in the region’s economy, providing construction materials and significant quantities of coal, gas, iron and mineral salts. Consequently, many parts of the region have also been affected by mining. Several parts of the region’s subsurface also provide groundwater from deep wells. The heating and cooling potential of the subsurface and its groundwater is increasingly being exploited as a source of ‘green energy’. Future uses of the subsurface may include underground storage of natural gas or ‘greenhouse gas’ waste. Some of the region’s deeper mudstone layers may also offer new sources of shale gas.