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Geology
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Geoscientist Jelle Zeilinga de Boer shares his expansive knowledge of Connecticut in a series of entertaining essays about the unexpected ways the land shapes the way we live. An utterly unique way to engage with local history, Stories in Stone reveals the secrets embedded in the world around us-in its rocks, deep below its surface, and in its unpredictable and outsized weather.
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A new technique has been helping scientists piece together how the Earth's continents were arranged 2.5 billion years ago.
The novel method allows scientists to recover rare minerals from rocks.
By analysing the composition of these minerals, researchers can precisely date ancient volcanic rocks for the first time.
By aligning rocks that have a similar age and orientation, the early landmasses can be pieced together.
This will aid the discovery of rocks rich in ore and oil deposits, say the scientists. The approach has already shown that Canada once bordered Zimbabwe, helping the mining industry identify new areas for exploration.
Dr Wouter Bleeker, from the Geological Survey of Canada, explained that much of the geology that exists today formed around 300 million years ago when the supercontinent Pangea existed.

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Geodynamic evolution of the Earth
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The fossil record is known to be biased by the unevenness of geographical and stratigraphical sampling, and the lack of exposed rocks containing fossils. In a recent Perspective in Science [2 January 2009] Professor Chris Hawkesworth from the University of Bristol and colleagues suggest that a similar unevenness biases the record of the evolution of the continental crust.
Rocks of the continental crust are dated using zircons, an extremely durable mineral that forms during the generation of granitic rocks. Some granites represent the formation of new continental crust and the zircons eroded out of these can persist for billions of years in sedimentary deposits. Other granites are generated from the melting of continental crust formed from such deposits. The age of that pre-existing crust can still be determined from the zircons, and the oldest zircon ever found is from such ancient sediments. It is 4.4 billion years old, only 150 million years younger than the planet itself.
It has long been known that the ages of rocks which form the continents are constrained to several peaks throughout Earth's history, but why this should be is open to question. The debate has previously focused on the likelihood that these peaks are related to deep-seated thermal anomalies within the Earth, resulting in so-called 'superplumes' which lead to periods of accelerated magmatism and the growth of continental crust.
More recently, the debate has turned to the potential correlation of peaks of continental magmatism with the periodic formation of 'supercontinents', such as Pangea and Gondwanaland. It is not clear, however, why the development of supercontinents should be associated with the generation of unusual volumes of igneous rocks. What seems more likely is that the age peaks in the continental rock record reflect a bias in preservation during periods of supercontinent formation where magmatism and crustal growth have an enhanced chance of preservation, because they are protected within the enveloping supercontinent.
In between periods of supercontinent formation, continuous magmatism at plate margins such as the Pacific 'Ring of Fire' where oceans are subducted beneath the continents, appears to have a much lower preservation potential, since crust along subduction zones is destroyed as fast as it is made.
Hawkesworth and his colleagues argue, therefore, that the age peaks within the continental crust are largely a bias related to preservation, or the lack of it, and that this needs to be taken into account when using the continental crust as a probe for the geodynamic evolution of the Earth. One implication is that at least since the Archaean (2.5 billion years ago) Earth geodynamics have been relatively uniformitarian.

Source University of Bristol

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RE: Geology
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New Surface Geology Map Breaks Fresh Ground For Tasmania
Mining companies, mineral explorers, geologists and the general public will be able to have a better understanding of Tasmanian and Australian geology, thanks to the first integrated Surface Geology Map of Australia.
The Minister for Energy and Resources, David Llewellyn, said that Tasmania had contributed to a cooperative program, led by Geoscience Australia, that has compiled a 1:1 million scale map which extends over the whole country in a seamless representation of Australias geology.

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Physicists at the University of Toronto have cracked the mystery behind the strange and uncannily well-ordered hexagonal columns found at such popular tourist sites as Northern Ireland's Giant's Causeway and California's Devil's Postpile, using water, corn starch, and a heat lamp.

"The size of the columns, which varies from site to site between a few inches and a few yards, is primarily determined by the speed at which lava from a volcanic eruption cools" - U of T physics professor Stephen Morris, who supervised the thesis project of PhD student Lucas Goehring.

Cooling lava sometimes forms strange column-shaped formations with a remarkable degree of order. The most famous of these hexagonal columns are found at the Giant's Causeway in Northern Ireland, where they are said to be the work of Finn MacCool, an Irish giant.
Using a combination of field observation, experiments and mathematical theory provided by Harvard University professor L. Mahadevan, they have solved the problem of what decides the size of the columns. The key to understanding the size of the columns was to reproduce the phenomenon in the lab. Using a mixture of water and corn starch which cracks as it dries out and forms very similar columns they carefully controlled the drying process, and established a relationship between the size of the columns and speed with which the drying front moved.

Source: University of Toronto

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Earth's oldest rocks
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Earth's most ancient rocks, with an age of 4.28 billion years, have been found on the shore of Hudson Bay, Canada.

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Jan Zalasiewicz, a lecturer in geology at the University of Leicester, has published a new study looking at the lasting impression made by mankind -100 million years hence.
He takes the perspective of alien explorers arriving on earth - their geologists study the layers of rock, using the many clues to piece together its history over several billion years
A story unfolds of moving and changing continents, rising and falling oceans, ice ages, and evidence of life going back many millions of years. They grow familiar with its phases of change, the rise of great new ecosystems, and occasional catastrophic collapses of life. But then they stumble on something quite different in a thin layer of rock: a striking signal of climate changes, extinctions and strange movements of wildlife across the planet. Following this trail, decoding clues in the rocks takes them to the petrified remains of cities, and finally to the fossilised bones of those, long dead, who built them.

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Geovandalism
You might have noticed that pretty as my komatiite deskcrop is, when I wanted to show the most impressive examples of spinifex textures, such as the variations in crystal size within a lava flow, I had to resort to field photos. In fact, whereas those photos come from a lovely fresh exposure in a stream bed, the hand sample on my desk comes from a nearby field, where the outcrop was rather badly weathered and horrible. This was deliberate: the small exposure in the stream is one of the best examples of spinifex textures found in the entire Barberton Greenstone Belt, and much of its value comes from being able to study the relationships within and between the different lava flows (in fact, we were visiting the locality with 60-odd students in tow for precisely this purpose). Hacking off a chunk simply to beautify my desk would therefore be rather irresponsible.
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The Public Information Geologist at The University of Texas at Austin Bureau of Economic Geology (BEG) answers hundreds of questions from the public every year. A common request is for information about their local geology and resources for student projects, youth group field trips, and family outings.
The Geologic Wonders of Texas web module was created as an online resource for students and families to learn about the earth across the State of Texas. Descriptions include significant geological features such as rocks and fossils, geologic age, additional resources, answers to frequently asked questions, and lesson plans.

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Fish helps geologists
The valuable food fish Antarctic toothfish (D. mawsoni) can be used as a bottom dredge with a large collection area. Such proposal was made by the specialists of the All-Russian Research Institute of Fish Industry and Oceanography and the Institute of Mineralogy, Geochemistry and Crystal Chemistry of Rare Elements. It makes no difference to the toothfish as the fish swallows stones all the same.

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