our rocks reveal the story of change h - metlinkgsa today. globes reconstructed globes show how the...
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Inverness
Ullapool
Stornoway
Lerwick
Aberdeen
Fort William
EdinburghGlasgow
Middlesbrough
NewcastleUpon Tyne
Carlisle
Londonderry
EnniskillenArmagh
Downpatrick
Coleraine
Belfast
Dublin
Birmingham
Leicester
Liverpool
Manchester
Sheffield
Nottingham
LeedsKingstonUpon Hull
Peterborough
Cambridge
Norwich
London
Reading
Oxford
Cardiff
Swansea
Aberystwyth
Dover
Exeter
Southampton
Bristol
Penzance
Plymouth
Omagh
Limerick
Cork
Galway
Athlone
Waterford
ESTA
Cambrian (E)
Mesoproterozoic (Y)
Palaeoproterozoic (Z)
Archaean (A)
Ordovician (O)
Silurian (S)
Devonian (D)
Carboniferous (C)
Permian (P)
Triassic (T)
Jurassic (J)
Cretaceous (K)
Palaeogene (G)
Quaternary (Q)
542 million
488 million
444 million
416 million
359 million
299 million
251 million
200 million
145 million
65 million
2.6 millionNeogene (N)
23 million
Ice
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Present day
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4600 million years ago Earth forms
Neoproterozoic (X)
time gap
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The northern half of Britain and Ireland occupy a position south of the equator and are separated
from the southern half by an ocean.
Britain and Ireland have collided and are located on the flank of a mountain chain on the edge of
an arid continent.
Positioned just north of the equator, Britain and Ireland experience desert conditions, while to the
south, Antarctica is covered by a vast ice-cap.
Britain and Ireland occupy a tropical position and are below sea level.
Britain and Ireland sit just south of their present position on the edge of the
opening North Atlantic ocean.
pres
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& s
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Temperature and sea level
through timePosition of Britain and Ireland through time
Geological periods and environments
Fossil evidence
ISBN 978-0-7518-3589-2
Our rockkss reveal the story of cchangeEarth's climate is predicted to change rapidly in ways that could have serious consequences for humanity. However, the climate has varied throughout the billions of years of Earth's geological history. Rocks record evidence for past climates including the extreme conditions that have been linked to mass extinctions. ’The present is the key to the past’ is a vital principle of geology. As geological understanding improves, so we are better able to forecast the impact future change may have on us — the past is the key to the future.
Many environments, and therefore the rocks formed in them, are directly influenced by climate. On this poster each environment is represented by a particular colour. Orange areas on the map, for instance, show where rocks that formed in ancient deserts may now be found. On the timeline, orange represents those geological periods when the climate was hot and arid in Britain and Ireland. The same colour is used to highlight photographs of a present-day desert and examples of ancient desert sandstones.
In other cases, however, rocks are formed by geological processes regardless of climate. For example, igneous intrusions, shown in red are formed during episodes of tectonic activity, independent of surface conditions.
The formation of some rocks may influence climate. For instance, thick sequences of coal 'locked up' atmospheric carbon dioxide as they formed. This greenhouse gas is now being released as we burn fossil fuels such as coal and oil. As another example, ash-filled skies from large volcanic eruptions block the Sun’s rays and cause global cooling.
On the map, letters in each coloured region refer to the age of the rocks, as shown in the timeline. For instance, rocks in areas marked 'J' are of Jurassic age, while 'PT' represents rocks of Permian to Triassic age.
P
Britain and Ireland sit just south of theirpresent position on the edge of the
North America
South
America
North
Europe
Africa
Gre
enland
Siberia
India
Australia
Antarctica
China
Equator
30° N
30° S
Mountains
Land
Britain and Ireland occupy a tropical position and are below sea level.
North
America
South
America
Europe
Africa
Greenla
nd Siberia
India
China
Equator
30° N
30° S
Australia
Antarctica
SE Asia
Central
Asia
Mountains
Land
Positioned just north of the equator, Britain andrIreland experience desert conditions while to the
Mountains
Land
Extent of Carboniferous -
Permian glaciations
North
America
South
America
Africa
Siberia
India
Spain
Equator
30° N
30° S
Australia
Antarctica
SE Asia
Britain and Ireland have collided and are located on the flank of a mountain chain on the edge of
North
America
South
America
Northern
Europe
Africa
Siberia
NW
China Equator
30° N
30° SAustralia
SE Asia
Southern
Europe
Mountains
Land
OO
The northern half of Britain and Ireland occupy a position south of the equator and are separated
North
America
Equator
30° N
30° S
Siberia
Northern
Europe
Africa
Britain and Ireland
Land
Phases of:
Colour banding on the timeline indicates the predominant environment or process.
Volcanic eruptions
Igneous intrusions
Mountain building
Typical examples of life-forms preserved as fossils in the rocks of Britain and Ireland.
The timeline before 542 million years is not drawn to scale but condensed to fit the poster. Time gaps indicate where the rock sequence is incomplete.
MASS EXTINCTION
MASS EXTINCTION
MASS EXTINCTION
MASS EXTINCTION
MASS EXTINCTION
Woolly Mammoth
Diplocynodon — alligator
Hyracotherium — early horse
Iguanodon — dinosaur
Scaphites — ammonite
Plesiosaur — marine reptile
Kuehneosuchus — flying lizard
Hyperodapedon — reptile
Elginia — early reptile
Tree-fern
Coral
Dragonfly
Cartilaginous fish
Dactylioceras — ammonite
Tetrapod — amphibian ancestor
Eurypterid — sea scorpion
Orthoceras — nautiloid
Didymograptus — graptolite
Paradoxides — trilobite
Jawless fish
Cooksonia — early land plant
Charnia — earliest complex animals
Temperature and sea level Position of Britain and Geological periods Fossil O kk l thh t f h
Sea levelThe blue curve* shows the average sea level compared to its present level for the whole Earth through geological time. This global sea-level may be affected by, for example, changes in the volume of water in the oceans or the changing shape of the ocean basins. However, relative sea-level changes affecting Britain and Ireland may have differed markedly from this 'global' curve. For example, there are localised vertical changes of the land caused by the movement and interaction of the plates that make the Earth’s crust, and by the formation and melting of ice-sheets. We cannot measure sea level in the ancient past directly, and a variety of techniques are used to estimate it, including the evidence of erosion by the sea, and fossil reefs approximating to sea level.
* The sea-level curve is simplified from one compiled by Joel Collins (1996 to 1998) for the article 'The carbonate analogs through time (CATT) hypothesis and the global atlas of carbonate fields. A systematic and predictive look at Phanerozoic carbonate systems' found in the SEPM (Society for Sedimentary geology) Special publication, No 89. 2008. 'Controls on carbonate platform and reef development' edited by Jeff Lukasik and J A T Simo.
TemperatureThe red curve† shows the average global temperature back to the Cambrian period. We cannot directly measure past temperatures, instead we use evidence preserved in the rocks that records temperature in a predictable way. One such method uses the proportion of the oxygen-18 isotope found in carbonate fossil shells; a high oxygen-18 content is associated with cold sea temperatures and times of glaciation.
The white 'bars' next to the curves shows ice ages — when ice caps covered the polar regions. Note that although the Earth experienced an ice age during the Permian, Britain and Ireland were enjoying tropical conditions.
† The temperature curve is derived from the article 'Celestial driver of Phanerozoic climate?' by Nir J Saviv and Jan Veizer published in July 2003 in the journal GSA Today.
GlobesThe reconstructed globes show how the continents have moved across the surface of the Earth through geological time as a result of plate tectonic activity, variously splitting apart and reassembling elsewhere in changing patterns.
Copyright This poster is the product of a collaboration between the British Geological Survey, the Geological Survey of Ireland and the Geological Survey of Northern Ireland. Unless otherwise stated, BGS © NERC 2009, © Geological Survey of Ireland 2009, and GSNI © Crown Copyright. All rights reserved.
UK Mainland topography © HarperCollins Publishers Ltd 2005.
Direction of ice flow
0 200 km
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Quaternary ice age deposits are found across most of Britain and Ireland. These relatively thin surface deposits are not shown on the map as they would obscure the underlying rocks. In the diagram above, the white area shows the maximum extent of ice during the most recent glacial advance, which ended 10 000 years ago. There have been many such advances during the past 2.6 million years. Each advance is followed by a warmer interglacial period, when the ice melts and retreats. We are now in an interglacial period — a temperate phase within a continuing ice age.
© Getty Images
Evidence: schist and gneiss are formed by the metamorphism of existing
rocks and are often deformed and folded with new minerals, such as
garnet, growing. Examples include the 'Lewisian' rocks of the North-West
Highlands of Scotland (Archaean).
Process: ancient rocks of varied origin, deformed and baked under high
temperatures and pressures during collision of Earth's tectonic plates, forming the
roots of mountain ranges.
© Getty Images
© Alex Donald
Photo by Woods Hole Oceanographic Institution
Tropical swamps, rivers and seas
Ice ages Warm seas
Cold and temperate seas
Ocean depths
Deserts
Ancient mountains
Volcanic eruptionsEvidence: basalt and rhyolite
lava and ash. Fine-grained crys-tals indicate rapid cooling at the
Earth's surface. Examples include the Antrim Plateau as seen at the Giant's Causeway (Palaeogene); English Lake District (Ordovician).
Process: fluid molten rock pours out at the surface as basalt lavas. Sticky rhyolite
erupts in violent explosions.
Proceess: fluid molten rock pours out at the:
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Igneous intrusionsEvidence: coarse-grained granite and
gabbro are evidence that magma crystallised slowly beneath the
Earth's surface. For example Cairngorm Mountains, Donegal, south Connemara (Silurian to Devonian) and Dartmoor (Carboniferous to Permian).
Process: intrusion of molten rock into the Earth's crust from below, crystallising
slowly at depth. May produce geothermal area of geysers and hot
springs at the surface.
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Evidence: sandstone, mudstone and coal. Beds rich in marine fossils
alternate with beds containing land and freshwater species. Examples include South Wales, the Midland Valley (Carboniferous)
and the Weald (Cretaceous).
Evidence: sandstone, mudstone and limestone (including chalk),
containing abundant fossils of warm-water species. For example Central Plain of Ireland, Peak District and Pennines (Carboniferous); North and South Downs (Cretaceous).
Environment: tropical swamps, rivers and shallow seas. Sand and mud
accumulate in layers, sometimes rich in plant remains.
Environment: warm, shallow to deep seas. Sand, mud and calcareous 'oozes'
accumulate and reefs build up.
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Evidence: desert dunes are pre-served as 'cross-bedded' sand-
stones with a rusty red colour. Desiccation cracks, salt and gyp-sum deposits indicate an arid climate. Examples are seen in Cork and Kerry (Devonian) and Cheshire (Permian to
Triassic).
Environment: hot, arid to semi-arid, with some rivers and temporary lakes. Wind
shapes sand into dunes; rivers deposit sand and gravel along channels;
evaporation forms salt pans.
Environment: hot arid to semi-arid with:
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Evidence: sandstone and mudstone containing fossils of marine
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Evidence: thick sequences of fine-grained sedimentary rocks, mainly
mudstone, containing fossils such as graptolites and trilobites. Examples are found in North Wales (Cambrian); Wicklow–Wexford
(Ordovician).
Environment: coastal waters to deep seas in cold to temperate latitudes. Sand and
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Environment: deep, cold and dark ocean floor. Mud slowly settles to form an
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Evidence: rock surfaces polished and grooved by ice; U-shaped valleys and
corries eroded by glaciers; drumlins moulded out of glacial debris; eskers formed by meltwaters; tills, sands and gravels cover most of Britain and Ireland (Quaternary). Older tillites are only rarely
preserved in bedrock.
Environment: very cold glacial periods with ice sheets and glaciers, alternating with
warmer interglacial periods.
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© Northern Ireland Environment Agency
© Getty Images
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