Wales (Cymru) - Geology - Revision history

Dbk at 09:06, 19 April 2016

2016-04-19T09:06:40Z

← Older revision		Revision as of 10:06, 19 April 2016
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	[[Category:~~18.~~ Wales (Cymru) \| 01]]		[[Category:Wales (Cymru) - summary \| 01]]

Jeth1 at 10:36, 4 November 2014

2014-11-04T10:36:57Z

Dbk at 09:31, 13 October 2014

2014-10-13T09:31:17Z

← Older revision		Revision as of 10:31, 13 October 2014
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	Figures P902276, P902273 and P902275 are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.		Figures P902276, P902273 and P902275 are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.
	[[Image:P902276.jpg\|thumb\|~~400px~~\|center\|Schematic cross-section of the geology of Anglesey and Northwest Wales. The alignment of the section and key are shown on Figure P902274. P902276.]]		[[Image:P902276.jpg\|thumb\|600px\|center\|Schematic cross-section of the geology of Anglesey and Northwest Wales. The alignment of the section and key are shown on Figure P902274. P902276.]]
	[[Image:P902273.jpg\|thumb\|~~400px~~\|center\|Schematic cross-section of the geology of Central Wales. The alignment of the section and key are shown on Figure P902274. P902273.]]		[[Image:P902273.jpg\|thumb\|600px\|center\|Schematic cross-section of the geology of Central Wales. The alignment of the section and key are shown on Figure P902274. P902273.]]
	[[Image:P902275.jpg\|thumb\|~~400px~~\|center\|Schematic cross-section of the geology of South Wales. The alignment of the section and key are shown on Figure P902274. P902275.]]		[[Image:P902275.jpg\|thumb\|600px\|center\|Schematic cross-section of the geology of South Wales. The alignment of the section and key are shown on Figure P902274. P902275.]]


	[[Category:18. Wales (Cymru) \| 01]]		[[Category:18. Wales (Cymru) \| 01]]

Dbk at 09:31, 13 October 2014

2014-10-13T09:31:04Z

← Older revision		Revision as of 10:31, 13 October 2014
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	Figures P902276, P902273 and P902275 are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.		Figures P902276, P902273 and P902275 are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.
	~~<gallery mode="packed">~~		[[Image:P902276.jpg\|thumb\|400px\|center\|Schematic cross-section of the geology of Anglesey and Northwest Wales. The alignment of the section and key are shown on Figure P902274. P902276.]]
	Image:P902276.jpg\|Schematic cross-section of the geology of Anglesey and Northwest Wales. The alignment of the section and key are shown on Figure P902274. P902276.		[[Image:P902273.jpg\|thumb\|400px\|center\|Schematic cross-section of the geology of Central Wales. The alignment of the section and key are shown on Figure P902274. P902273.]]
	Image:P902273.jpg\|Schematic cross-section of the geology of Central Wales. The alignment of the section and key are shown on Figure P902274. P902273.		[[Image:P902275.jpg\|thumb\|400px\|center\|Schematic cross-section of the geology of South Wales. The alignment of the section and key are shown on Figure P902274. P902275.]]
	Image:P902275.jpg\|Schematic cross-section of the geology of South Wales. The alignment of the section and key are shown on Figure P902274. P902275.
	~~</gallery>~~

	[[Category:18. Wales (Cymru) \| 01]]		[[Category:18. Wales (Cymru) \| 01]]

Dbk at 09:29, 13 October 2014

2014-10-13T09:29:17Z

← Older revision		Revision as of 10:29, 13 October 2014
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	Figures P902276, P902273 and P902275 are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.		Figures P902276, P902273 and P902275 are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.
	<gallery ~~widths~~=~~{width}px~~>		<gallery mode="packed">
	Image:P902276.jpg\|Schematic cross-section of the geology of Anglesey and Northwest Wales. The alignment of the section and key are shown on Figure P902274. P902276.		Image:P902276.jpg\|Schematic cross-section of the geology of Anglesey and Northwest Wales. The alignment of the section and key are shown on Figure P902274. P902276.
	Image:P902273.jpg\|Schematic cross-section of the geology of Central Wales. The alignment of the section and key are shown on Figure P902274. P902273.		Image:P902273.jpg\|Schematic cross-section of the geology of Central Wales. The alignment of the section and key are shown on Figure P902274. P902273.

Dbk at 09:28, 13 October 2014

2014-10-13T09:28:49Z

← Older revision		Revision as of 10:28, 13 October 2014
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	Figures P902276, P902273 and P902275 are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.		Figures P902276, P902273 and P902275 are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.
	<gallery widths={width}~~300px~~>		<gallery widths={width}px>
	Image:P902276.jpg\|Schematic cross-section of the geology of Anglesey and Northwest Wales. The alignment of the section and key are shown on Figure P902274. P902276.		Image:P902276.jpg\|Schematic cross-section of the geology of Anglesey and Northwest Wales. The alignment of the section and key are shown on Figure P902274. P902276.
	Image:P902273.jpg\|Schematic cross-section of the geology of Central Wales. The alignment of the section and key are shown on Figure P902274. P902273.		Image:P902273.jpg\|Schematic cross-section of the geology of Central Wales. The alignment of the section and key are shown on Figure P902274. P902273.

Dbk at 09:27, 13 October 2014

2014-10-13T09:27:55Z

← Older revision		Revision as of 10:27, 13 October 2014
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	Figures P902276, P902273 and P902275 are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.		Figures P902276, P902273 and P902275 are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.
	<gallery widths={~~300~~}px>		<gallery widths={width}300px>
	Image:P902276.jpg\|Schematic cross-section of the geology of Anglesey and Northwest Wales. The alignment of the section and key are shown on Figure P902274. P902276.		Image:P902276.jpg\|Schematic cross-section of the geology of Anglesey and Northwest Wales. The alignment of the section and key are shown on Figure P902274. P902276.
	Image:P902273.jpg\|Schematic cross-section of the geology of Central Wales. The alignment of the section and key are shown on Figure P902274. P902273.		Image:P902273.jpg\|Schematic cross-section of the geology of Central Wales. The alignment of the section and key are shown on Figure P902274. P902273.

Dbk at 09:27, 13 October 2014

2014-10-13T09:27:42Z

← Older revision		Revision as of 10:27, 13 October 2014
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	Figures P902276, P902273 and P902275 are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.		Figures P902276, P902273 and P902275 are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.
	<gallery ~~mode~~=~~"packed"~~>		<gallery widths={300}px>
	Image:P902276.jpg\|Schematic cross-section of the geology of Anglesey and Northwest Wales. The alignment of the section and key are shown on Figure P902274. P902276.		Image:P902276.jpg\|Schematic cross-section of the geology of Anglesey and Northwest Wales. The alignment of the section and key are shown on Figure P902274. P902276.
	Image:P902273.jpg\|Schematic cross-section of the geology of Central Wales. The alignment of the section and key are shown on Figure P902274. P902273.		Image:P902273.jpg\|Schematic cross-section of the geology of Central Wales. The alignment of the section and key are shown on Figure P902274. P902273.

Dbk at 09:26, 13 October 2014

2014-10-13T09:26:34Z

← Older revision		Revision as of 10:26, 13 October 2014
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	Figures P902276, P902273 and P902275 are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.		Figures P902276, P902273 and P902275 are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.
	<gallery mode="packed">		<gallery mode="packed">
	Image:P902276.jpg~~\|thumb\|300px\|left~~\|Schematic cross-section of the geology of Anglesey and Northwest Wales. The alignment of the section and key are shown on Figure P902274. P902276.		Image:P902276.jpg\|Schematic cross-section of the geology of Anglesey and Northwest Wales. The alignment of the section and key are shown on Figure P902274. P902276.
	Image:P902273.jpg~~\|thumb\|300px\|center~~\|Schematic cross-section of the geology of Central Wales. The alignment of the section and key are shown on Figure P902274. P902273.		Image:P902273.jpg\|Schematic cross-section of the geology of Central Wales. The alignment of the section and key are shown on Figure P902274. P902273.
	Image:P902275.jpg~~\|thumb\|300px\|right~~\|Schematic cross-section of the geology of South Wales. The alignment of the section and key are shown on Figure P902274. P902275.		Image:P902275.jpg\|Schematic cross-section of the geology of South Wales. The alignment of the section and key are shown on Figure P902274. P902275.
	</gallery>		</gallery>

	[[Category:18. Wales (Cymru) \| 01]]		[[Category:18. Wales (Cymru) \| 01]]

Dbk at 09:25, 13 October 2014

2014-10-13T09:25:29Z

← Older revision		Revision as of 10:25, 13 October 2014
Line 15:		Line 15:

	Figures P902276, P902273 and P902275 are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.		Figures P902276, P902273 and P902275 are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.
	<gallery>		<gallery mode="packed">
	Image:P902276.jpg\|thumb\|300px\|left\|Schematic cross-section of the geology of Anglesey and Northwest Wales. The alignment of the section and key are shown on Figure P902274. P902276.		Image:P902276.jpg\|thumb\|300px\|left\|Schematic cross-section of the geology of Anglesey and Northwest Wales. The alignment of the section and key are shown on Figure P902274. P902276.
	Image:P902273.jpg\|thumb\|300px\|center\|Schematic cross-section of the geology of Central Wales. The alignment of the section and key are shown on Figure P902274. P902273.		Image:P902273.jpg\|thumb\|300px\|center\|Schematic cross-section of the geology of Central Wales. The alignment of the section and key are shown on Figure P902274. P902273.

← Older revision		Revision as of 10:31, 13 October 2014
Line 15:		Line 15:

	Figures P902276, P902273 and P902275 are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.		Figures P902276, P902273 and P902275 are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.
	[[Image:P902276.jpg\|thumb\|~~400px~~\|center\|Schematic cross-section of the geology of Anglesey and Northwest Wales. The alignment of the section and key are shown on Figure P902274. P902276.]]		[[Image:P902276.jpg\|thumb\|600px\|center\|Schematic cross-section of the geology of Anglesey and Northwest Wales. The alignment of the section and key are shown on Figure P902274. P902276.]]
	[[Image:P902273.jpg\|thumb\|~~400px~~\|center\|Schematic cross-section of the geology of Central Wales. The alignment of the section and key are shown on Figure P902274. P902273.]]		[[Image:P902273.jpg\|thumb\|600px\|center\|Schematic cross-section of the geology of Central Wales. The alignment of the section and key are shown on Figure P902274. P902273.]]
	[[Image:P902275.jpg\|thumb\|~~400px~~\|center\|Schematic cross-section of the geology of South Wales. The alignment of the section and key are shown on Figure P902274. P902275.]]		[[Image:P902275.jpg\|thumb\|600px\|center\|Schematic cross-section of the geology of South Wales. The alignment of the section and key are shown on Figure P902274. P902275.]]


	[[Category:18. Wales (Cymru) \| 01]]		[[Category:18. Wales (Cymru) \| 01]]

← Older revision		Revision as of 11:36, 4 November 2014
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	==Recent surface deposits==		==Recent surface deposits==
	Much of Wales is covered by geological deposits of relatively recent origin, formed over the past 2 to 3 million years and spanning the ~~Ice Ages~~ and ~~Interglacial~~ periods. These are known as superficial deposits and include gravelly clays and sand and gravel laid down during the last Ice Age, sand, silt and gravel deposited by rivers along valley floors over the last 10,000 years and peat bogs that formed mostly in upland areas. Some of these shallow deposits locally form greater thicknesses up to 50 m in areas such as the ~~Lower~~ Swansea ~~Valley~~, which has been scoured out by the action of glaciers. Most of the superficial deposits are soft and easily eroded, as they have not been deeply buried and consolidated to form strong rocks.		Much of Wales is covered by geological deposits of relatively recent origin, formed over the past 2 to 3 million years and spanning the ice ages and interglacial periods. These are known as superficial deposits and include gravelly clays and sand and gravel laid down during the last Ice Age, sand, silt and gravel deposited by rivers along valley floors over the last 10,000 years, and peat bogs that formed mostly in upland areas. Some of these shallow deposits locally form greater thicknesses up to 50 m in areas such as the lower Swansea valley, which has been scoured out by the action of glaciers. Most of the superficial deposits are soft and easily eroded, as they have not been deeply buried and consolidated to form strong rocks.

	==Geology at depth==		==Geology at depth==
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	* The sedimentary bedrock geology is composed of quite hard rocks which were deposited up to 415 million years ago as layers of sediment in shallow seas, coastal plains or by the action of ancient river systems in times when Wales lay closer to the Equator and the climate and landscape were very different from those of today.		* The sedimentary bedrock geology is composed of quite hard rocks which were deposited up to 415 million years ago as layers of sediment in shallow seas, coastal plains or by the action of ancient river systems in times when Wales 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 415 million years old and mainly comprises harder, denser rocks which have been strongly compacted and folded. Most of the basement rocks comprise strongly folded and faulted grey mudstones, siltstones and sandstones. Other basement rocks include both rocks that are products of volcanic activity (volcanic rocks) or formed from the solidification of molten rock deep below the surface (igneous intrusive rocks) ~~and~~ rocks which may have started as either sediments or intrusions but have subsequently been changed into a different form by the high temperatures and pressures ~~which~~ they have been subjected to since (metamorphic rocks), such as those exposed in parts of Anglesey.		* The basement geology, which underlies the bedrock, is over 415 million years old and mainly comprises harder, denser rocks which have been strongly compacted and folded. Most of the basement rocks comprise strongly folded and faulted grey mudstones, siltstones and sandstones. Other basement rocks include both rocks that are products of volcanic activity (volcanic rocks) or formed from the solidification of molten rock deep below the surface (igneous intrusive rocks). There are also rocks which may have started as either sediments or intrusions but have subsequently been changed into a different form by the high temperatures and pressures that they have been subjected to since (metamorphic rocks), such as those exposed in parts of Anglesey.

	In the course of the past 540 million years there have been periods when the area of Wales formed a landmass and was being eroded, and other periods when it was sinking and new layers of sediment were being deposited. The history of erosion and deposition has not been the same in all parts of Wales. The oldest sedimentary rocks are sandstones, siltstones and mudstones. These rocks were buried and deformed by the forces of continental plates moving against each other.		In the course of the past 540 million years there have been periods when the area of Wales formed a landmass and was being eroded, and other periods when it was sinking and new layers of sediment were being deposited. The history of erosion and deposition has not been the same in all parts of Wales. The oldest sedimentary rocks are sandstones, siltstones and mudstones. These rocks were buried and deformed by the forces of continental plates moving against each other.
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	Subsequently, younger sequences of sedimentary rocks, including limestones, sandstones and clays, were laid down. Although in some parts of Wales, sediments continued to be deposited relatively constantly, in most areas deposition stopped and instead uplift and erosion took place for tens of millions of years. As a result when deposition restarted the next layer was laid down on a variety of different older sediments. This situation where younger rocks rest directly on rocks of different older ages because of uplift and erosion is referred to by geologists as an unconformity.		Subsequently, younger sequences of sedimentary rocks, including limestones, sandstones and clays, were laid down. Although in some parts of Wales, sediments continued to be deposited relatively constantly, in most areas deposition stopped and instead uplift and erosion took place for tens of millions of years. As a result when deposition restarted the next layer was laid down on a variety of different older sediments. This situation where younger rocks rest directly on rocks of different older ages because of uplift and erosion is referred to by geologists as an unconformity.

	The geology of Wales is also affected by geological faults where the rocks on each side of the fracture have moved relative to one another. The relative movement of the rocks on either side of some of these faults can be very significant resulting in dramatic changes in geology over short distances. These include the Bala Fault which runs 50 km in a ~~northeast~~ to ~~southwest~~ direction through the town of Bala and the Welsh Borderland Fault Zone which is a zone of faulting and associated folding which runs ~~northeastwards~~ through Wales from Pembrokeshire through Carmarthenshire and Powys into Shropshire.		The geology of Wales is also affected by geological faults where the rocks on each side of the fracture have moved relative to one another. The relative movement of the rocks on either side of some of these faults can be very significant resulting in dramatic changes in geology over short distances. These include the Bala Fault which runs 50 km in a north-east to south-west direction through the town of Bala and the Welsh Borderland Fault Zone which is a zone of faulting and associated folding which runs north-eastwards through Wales from Pembrokeshire through Carmarthenshire and Powys into Shropshire.

	Figures P902276, P902273 and P902275 are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.		'''Figures P902276''', '''P902273''' and '''P902275''' are vertical sections through the geology, referred to as geological cross-sections, which illustrate the variations across the region.
	[[Image:P902276.jpg\|thumb\|600px\|center\|Schematic cross-section of the geology of Anglesey and ~~Northwest~~ Wales. The alignment of the section and key are shown on Figure P902274. P902276.]]		[[Image:P902276.jpg\|thumb\|600px\|center\|Schematic cross-section of the geology of Anglesey and north-west Wales. The alignment of the section and key are shown on '''Figure P902274'''. P902276.]]
	[[Image:P902273.jpg\|thumb\|600px\|center\|Schematic cross-section of the geology of ~~Central~~ Wales. The alignment of the section and key are shown on Figure P902274. P902273.]]		[[Image:P902273.jpg\|thumb\|600px\|center\|Schematic cross-section of the geology of central Wales. The alignment of the section and key are shown on '''Figure P902274'''. P902273.]]
	[[Image:P902275.jpg\|thumb\|600px\|center\|Schematic cross-section of the geology of South Wales. The alignment of the section and key are shown on Figure P902274. P902275.]]		[[Image:P902275.jpg\|thumb\|600px\|center\|Schematic cross-section of the geology of South Wales. The alignment of the section and key are shown on '''Figure P902274'''. P902275.]]


	[[Category:18. Wales (Cymru) \| 01]]		[[Category:18. Wales (Cymru) \| 01]]