Bedrock Geology UK North:Introduction - Revision history

Dbk at 13:48, 29 January 2015

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	'''These pages aims to assist the interpretation''' of the accompanying 1:625 000 scale map by providing descriptions of the rock types, and by giving a brief explanation of their origins. A convention in geological descriptions is to always start at the bottom, with the oldest rocks, and work upwards towards the youngest rocks. This way we start closest to the beginning of everything. In British terms, the beginning — the oldest rock — is marked by the three-billion-year-old gneisses in the Lewisian Gneiss Complex of north-west Scotland (Hebridean terrane). But to keep things in perspective, remember that the Earth itself (and the rest of the Solar System) formed about 4.6 billion years ago — and even that was quite recent in comparison to the initiation of the Universe between 13 and 14 billion years ago.		'''These pages aims to assist the interpretation''' of the accompanying 1:625 000 scale map by providing descriptions of the rock types, and by giving a brief explanation of their origins. A convention in geological descriptions is to always start at the bottom, with the oldest rocks, and work upwards towards the youngest rocks. This way we start closest to the beginning of everything. In British terms, the beginning — the oldest rock — is marked by the three-billion-year-old gneisses in the Lewisian Gneiss Complex of north-west Scotland (Hebridean terrane). But to keep things in perspective, remember that the Earth itself (and the rest of the Solar System) formed about 4.6 billion years ago — and even that was quite recent in comparison to the initiation of the Universe between 13 and 14 billion years ago.

			==Bedrock Geology UK North - contents==
			{{bedrockNorth}}


	[[category:Bedrock Geology UK North\| 00]]		[[category:Bedrock Geology UK North\| 00]]

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	==A brief history of the 1:625 000 scale maps==		==A brief history of the 1:625 000 scale maps==

Jeth1 at 09:24, 12 June 2014

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	'''The geological history of Britain''' shows an intermittent drift from high southern latitudes to our present northern locale, punctuated along the way by several episodes of continental collision and break-up. The nature of the rock record gives some indication of continental positions — evidence for desert sandstones or equatorial forests, perhaps, or the type of animals preserved as fossils — but an important modern technique allows us to locate the original position of rocks by their palaeomagnetism. Just as the isotopic character of a once-molten rock can be used to calculate its age, so the palaeomagnetic fabric of a rock helps to determine the place on the Earth where it was created. This is possible because the ambient magnetic field at the time of cooling can be locked into a rock and retained as a geographical record over a geological time span.		'''The geological history of Britain''' shows an intermittent drift from high southern latitudes to our present northern locale, punctuated along the way by several episodes of continental collision and break-up. The nature of the rock record gives some indication of continental positions — evidence for desert sandstones or equatorial forests, perhaps, or the type of animals preserved as fossils — but an important modern technique allows us to locate the original position of rocks by their palaeomagnetism. Just as the isotopic character of a once-molten rock can be used to calculate its age, so the palaeomagnetic fabric of a rock helps to determine the place on the Earth where it was created. This is possible because the ambient magnetic field at the time of cooling can be locked into a rock and retained as a geographical record over a geological time span.

	'''As we go back in time''', interpretation of the data becomes more difficult, and the conclusions drawn become less confident. Nevertheless it is fairly clear that by around 800 million years ago, all of the Earth’s land areas were combined into one massive ‘supercontinent’ known as Rodinia, though not all of the future parts of Britain were adjacent to each other ('''Figure 4a'''). By about 500 million years ago Rodinia had fragmented and a huge ocean — the Iapetus Ocean ('''Figure 4b''') — separated England, Wales and southern Ireland (then part of the Avalonia–Gondwana continent) from Scotland and the northern part of Ireland (then part of the Laurentia continent). The Iapetus Ocean progressively closed over the next 100 million years ('''Figure 4c''') and by 400 million years ago the different parts of northern Britain had been juxtaposed ('''Figure 4d''') though the extreme south and much of Europe did not catch up for another 50 million years. By about 250 million years ago, the Earth’s land areas had recombined to form the ‘supercontinent’ known as Pangaea ('''Figure 4e''') but, in its turn, Pangaea began to break up about 150 million years ago ('''Figure 4f''') and, by 50 million years ago, development of the Atlantic Ocean was well under way ('''Figure 4g''').		'''As we go back in time''', interpretation of the data becomes more difficult, and the conclusions drawn become less confident. Nevertheless it is fairly clear that by around 800 million years ago, all of the Earth’s land areas were combined into one massive ‘supercontinent’ known as Rodinia, though not all of the future parts of Britain were adjacent to each other ('''Figure P785799a'''). By about 500 million years ago Rodinia had fragmented and a huge ocean — the Iapetus Ocean ('''Figure P785799b''') — separated England, Wales and southern Ireland (then part of the Avalonia–Gondwana continent) from Scotland and the northern part of Ireland (then part of the Laurentia continent). The Iapetus Ocean progressively closed over the next 100 million years ('''Figure P785799c''') and by 400 million years ago the different parts of northern Britain had been juxtaposed ('''Figure P785799d''') though the extreme south and much of Europe did not catch up for another 50 million years. By about 250 million years ago, the Earth’s land areas had recombined to form the ‘supercontinent’ known as Pangaea ('''Figure P785800e''') but, in its turn, Pangaea began to break up about 150 million years ago ('''Figure P785800f''') and, by 50 million years ago, development of the Atlantic Ocean was well under way ('''Figure P785800g''').

	'''This remarkable, if convoluted''', geological history has produced the sequence and distribution of rocks seen in Britain and Ireland. The succession of collision and accretion events also means that they can be viewed, especially in the north, as a series of geological ''terranes'', each one characterised by a distinctive rock assemblage and tectonic history, but separated from its neighbours by major fault zones ('''Figure P785801'''). All of this helps to explain some seemingly paradoxical relationships that were inexplicable when the first editions of the 1:625 000 scale maps were produced in 1948, well before the development of plate tectonic interpretations from about 1960 onwards. For example, much of Scottish geology can be compared more closely with that of Newfoundland and Greenland rather than England and Wales, while the older rocks of England and Wales have more in common with those of Nova Scotia than with those of Scotland, immediately to the north.		'''This remarkable, if convoluted''', geological history has produced the sequence and distribution of rocks seen in Britain and Ireland. The succession of collision and accretion events also means that they can be viewed, especially in the north, as a series of geological ''terranes'', each one characterised by a distinctive rock assemblage and tectonic history, but separated from its neighbours by major fault zones ('''Figure P785801'''). All of this helps to explain some seemingly paradoxical relationships that were inexplicable when the first editions of the 1:625 000 scale maps were produced in 1948, well before the development of plate tectonic interpretations from about 1960 onwards. For example, much of Scottish geology can be compared more closely with that of Newfoundland and Greenland rather than England and Wales, while the older rocks of England and Wales have more in common with those of Nova Scotia than with those of Scotland, immediately to the north.

Dbk: Protected "Bedrock Geology UK North:Introduction" ([Edit=Allow only administrators] (indefinite) [Move=Allow only administrators] (indefinite)) [cascading]

2014-06-11T12:19:17Z

Protected "Bedrock Geology UK North:Introduction" ([Edit=Allow only administrators] (indefinite) [Move=Allow only administrators] (indefinite)) [cascading]

← Older revision		Revision as of 13:19, 11 June 2014
(No difference)

Dbk: /* Stratigraphy and plate tectonics */

2014-06-03T12:10:27Z

Stratigraphy and plate tectonics

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	[[Image:P785800.jpg\|thumb\|center\|500px\| Moving continents: reconstructions of the position of the main landmasses and their continental shelves form Neoproterozoic to Cenozoic times. Modern coastlines are included for reference. P785800.]]		[[Image:P785800.jpg\|thumb\|center\|500px\| Moving continents: reconstructions of the position of the main landmasses and their continental shelves form Neoproterozoic to Cenozoic times. Modern coastlines are included for reference. P785800.]]

	'''~~This booklet~~ aims to assist the interpretation''' of the accompanying 1:625 000 scale map by providing descriptions of the rock types, and by giving a brief explanation of their origins. A convention in geological descriptions is to always start at the bottom, with the oldest rocks, and work upwards towards the youngest rocks. This way we start closest to the beginning of everything. In British terms, the beginning — the oldest rock — is marked by the three-billion-year-old gneisses in the Lewisian Gneiss Complex of north-west Scotland (Hebridean terrane). But to keep things in perspective, remember that the Earth itself (and the rest of the Solar System) formed about 4.6 billion years ago — and even that was quite recent in comparison to the initiation of the Universe between 13 and 14 billion years ago.		'''These pages aims to assist the interpretation''' of the accompanying 1:625 000 scale map by providing descriptions of the rock types, and by giving a brief explanation of their origins. A convention in geological descriptions is to always start at the bottom, with the oldest rocks, and work upwards towards the youngest rocks. This way we start closest to the beginning of everything. In British terms, the beginning — the oldest rock — is marked by the three-billion-year-old gneisses in the Lewisian Gneiss Complex of north-west Scotland (Hebridean terrane). But to keep things in perspective, remember that the Earth itself (and the rest of the Solar System) formed about 4.6 billion years ago — and even that was quite recent in comparison to the initiation of the Universe between 13 and 14 billion years ago.


	[[category:Bedrock Geology UK North\| 00]]		[[category:Bedrock Geology UK North\| 00]]

Dbk: /* Stratigraphy and plate tectonics */

2014-06-03T12:09:58Z

Stratigraphy and plate tectonics

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	[[Image:P785799.jpg\|thumb\|center\|710px\| P785799.]]		[[Image:P785799.jpg\|thumb\|center\|710px\| P785799.]]
	[[Image:P785800.jpg\|thumb\|center\|500px\| Moving continents: reconstructions of the position of the main landmasses and their continental shelves form Neoproterozoic to Cenozoic times. Modern coastlines are included for reference. P785800.]]		[[Image:P785800.jpg\|thumb\|center\|500px\| Moving continents: reconstructions of the position of the main landmasses and their continental shelves form Neoproterozoic to Cenozoic times. Modern coastlines are included for reference. P785800.]]

	'''This booklet aims to assist the interpretation''' of the accompanying 1:625 000 scale map by providing descriptions of the rock types, and by giving a brief explanation of their origins. A convention in geological descriptions is to always start at the bottom, with the oldest rocks, and work upwards towards the youngest rocks. This way we start closest to the beginning of everything. In British terms, the beginning — the oldest rock — is marked by the three-billion-year-old gneisses in the Lewisian Gneiss Complex of north-west Scotland (Hebridean terrane). But to keep things in perspective, remember that the Earth itself (and the rest of the Solar System) formed about 4.6 billion years ago — and even that was quite recent in comparison to the initiation of the Universe between 13 and 14 billion years ago.		'''This booklet aims to assist the interpretation''' of the accompanying 1:625 000 scale map by providing descriptions of the rock types, and by giving a brief explanation of their origins. A convention in geological descriptions is to always start at the bottom, with the oldest rocks, and work upwards towards the youngest rocks. This way we start closest to the beginning of everything. In British terms, the beginning — the oldest rock — is marked by the three-billion-year-old gneisses in the Lewisian Gneiss Complex of north-west Scotland (Hebridean terrane). But to keep things in perspective, remember that the Earth itself (and the rest of the Solar System) formed about 4.6 billion years ago — and even that was quite recent in comparison to the initiation of the Universe between 13 and 14 billion years ago.


	[[category:Bedrock Geology UK North\| 00]]		[[category:Bedrock Geology UK North\| 00]]

Dbk: /* Stratigraphy and plate tectonics */

2014-06-03T12:08:33Z

Stratigraphy and plate tectonics

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	'''This remarkable, if convoluted''', geological history has produced the sequence and distribution of rocks seen in Britain and Ireland. The succession of collision and accretion events also means that they can be viewed, especially in the north, as a series of geological ''terranes'', each one characterised by a distinctive rock assemblage and tectonic history, but separated from its neighbours by major fault zones ('''Figure P785801'''). All of this helps to explain some seemingly paradoxical relationships that were inexplicable when the first editions of the 1:625 000 scale maps were produced in 1948, well before the development of plate tectonic interpretations from about 1960 onwards. For example, much of Scottish geology can be compared more closely with that of Newfoundland and Greenland rather than England and Wales, while the older rocks of England and Wales have more in common with those of Nova Scotia than with those of Scotland, immediately to the north.		'''This remarkable, if convoluted''', geological history has produced the sequence and distribution of rocks seen in Britain and Ireland. The succession of collision and accretion events also means that they can be viewed, especially in the north, as a series of geological ''terranes'', each one characterised by a distinctive rock assemblage and tectonic history, but separated from its neighbours by major fault zones ('''Figure P785801'''). All of this helps to explain some seemingly paradoxical relationships that were inexplicable when the first editions of the 1:625 000 scale maps were produced in 1948, well before the development of plate tectonic interpretations from about 1960 onwards. For example, much of Scottish geology can be compared more closely with that of Newfoundland and Greenland rather than England and Wales, while the older rocks of England and Wales have more in common with those of Nova Scotia than with those of Scotland, immediately to the north.

	[[Image:P785799.jpg\|thumb\|center\|710px\| ]]		[[Image:P785799.jpg\|thumb\|center\|710px\| P785799.]]
	[[Image:P785800.jpg\|thumb\|center\|500px\| Moving continents: reconstructions of the position of the main landmasses and their continental shelves form Neoproterozoic to Cenozoic times. Modern coastlines are included for reference. ~~P785799 &~~ P785800.]]		[[Image:P785800.jpg\|thumb\|center\|500px\| Moving continents: reconstructions of the position of the main landmasses and their continental shelves form Neoproterozoic to Cenozoic times. Modern coastlines are included for reference. P785800.]]
	'''This booklet aims to assist the interpretation''' of the accompanying 1:625 000 scale map by providing descriptions of the rock types, and by giving a brief explanation of their origins. A convention in geological descriptions is to always start at the bottom, with the oldest rocks, and work upwards towards the youngest rocks. This way we start closest to the beginning of everything. In British terms, the beginning — the oldest rock — is marked by the three-billion-year-old gneisses in the Lewisian Gneiss Complex of north-west Scotland (Hebridean terrane). But to keep things in perspective, remember that the Earth itself (and the rest of the Solar System) formed about 4.6 billion years ago — and even that was quite recent in comparison to the initiation of the Universe between 13 and 14 billion years ago.		'''This booklet aims to assist the interpretation''' of the accompanying 1:625 000 scale map by providing descriptions of the rock types, and by giving a brief explanation of their origins. A convention in geological descriptions is to always start at the bottom, with the oldest rocks, and work upwards towards the youngest rocks. This way we start closest to the beginning of everything. In British terms, the beginning — the oldest rock — is marked by the three-billion-year-old gneisses in the Lewisian Gneiss Complex of north-west Scotland (Hebridean terrane). But to keep things in perspective, remember that the Earth itself (and the rest of the Solar System) formed about 4.6 billion years ago — and even that was quite recent in comparison to the initiation of the Universe between 13 and 14 billion years ago.


	[[category:Bedrock Geology UK North\| 00]]		[[category:Bedrock Geology UK North\| 00]]

Dbk: /* Stratigraphy and plate tectonics */

2014-06-03T12:07:48Z

Stratigraphy and plate tectonics

← Older revision		Revision as of 13:07, 3 June 2014
Line 41:		Line 41:
	'''This remarkable, if convoluted''', geological history has produced the sequence and distribution of rocks seen in Britain and Ireland. The succession of collision and accretion events also means that they can be viewed, especially in the north, as a series of geological ''terranes'', each one characterised by a distinctive rock assemblage and tectonic history, but separated from its neighbours by major fault zones ('''Figure P785801'''). All of this helps to explain some seemingly paradoxical relationships that were inexplicable when the first editions of the 1:625 000 scale maps were produced in 1948, well before the development of plate tectonic interpretations from about 1960 onwards. For example, much of Scottish geology can be compared more closely with that of Newfoundland and Greenland rather than England and Wales, while the older rocks of England and Wales have more in common with those of Nova Scotia than with those of Scotland, immediately to the north.		'''This remarkable, if convoluted''', geological history has produced the sequence and distribution of rocks seen in Britain and Ireland. The succession of collision and accretion events also means that they can be viewed, especially in the north, as a series of geological ''terranes'', each one characterised by a distinctive rock assemblage and tectonic history, but separated from its neighbours by major fault zones ('''Figure P785801'''). All of this helps to explain some seemingly paradoxical relationships that were inexplicable when the first editions of the 1:625 000 scale maps were produced in 1948, well before the development of plate tectonic interpretations from about 1960 onwards. For example, much of Scottish geology can be compared more closely with that of Newfoundland and Greenland rather than England and Wales, while the older rocks of England and Wales have more in common with those of Nova Scotia than with those of Scotland, immediately to the north.

	[[Image:P785799.jpg\|center\|710px\| ]]		[[Image:P785799.jpg\|thumb\|center\|710px\| ]]
	[[Image:P785800.jpg\|center\|500px\| Moving continents: reconstructions of the position of the main landmasses and their continental shelves form Neoproterozoic to Cenozoic times. Modern coastlines are included for reference. P785799 & P785800.]]		[[Image:P785800.jpg\|thumb\|center\|500px\| Moving continents: reconstructions of the position of the main landmasses and their continental shelves form Neoproterozoic to Cenozoic times. Modern coastlines are included for reference. P785799 & P785800.]]
	'''This booklet aims to assist the interpretation''' of the accompanying 1:625 000 scale map by providing descriptions of the rock types, and by giving a brief explanation of their origins. A convention in geological descriptions is to always start at the bottom, with the oldest rocks, and work upwards towards the youngest rocks. This way we start closest to the beginning of everything. In British terms, the beginning — the oldest rock — is marked by the three-billion-year-old gneisses in the Lewisian Gneiss Complex of north-west Scotland (Hebridean terrane). But to keep things in perspective, remember that the Earth itself (and the rest of the Solar System) formed about 4.6 billion years ago — and even that was quite recent in comparison to the initiation of the Universe between 13 and 14 billion years ago.		'''This booklet aims to assist the interpretation''' of the accompanying 1:625 000 scale map by providing descriptions of the rock types, and by giving a brief explanation of their origins. A convention in geological descriptions is to always start at the bottom, with the oldest rocks, and work upwards towards the youngest rocks. This way we start closest to the beginning of everything. In British terms, the beginning — the oldest rock — is marked by the three-billion-year-old gneisses in the Lewisian Gneiss Complex of north-west Scotland (Hebridean terrane). But to keep things in perspective, remember that the Earth itself (and the rest of the Solar System) formed about 4.6 billion years ago — and even that was quite recent in comparison to the initiation of the Universe between 13 and 14 billion years ago.


	[[category:Bedrock Geology UK North\| 00]]		[[category:Bedrock Geology UK North\| 00]]