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When the Mediterranean evaporated
Much to geologists’ surprise seismic surveys and drilling of the Mediterranean basin revealed that it is floored by an immense thickness of evaporite salts, laid down during the Late Miocene about 6 Ma...
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Quaternary snatched from jaws of extinction
At a stormy meeting in August 2004at the 32nd International Geological Congress in Florence, a rearguard action was mounted by a group of stalwart geologists to thwart an attempt to expunge the last...
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BIFs and bacteria
Banded iron formations from the late Archaean, Palaeoproterozoic, and in a few short time intervals linked with Neoproterozoic tillites, have long fascinated geoscientists with their counterintuitive...
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The ‘real’ Flood
At the end of the Miocene tectonic uplift in the region of the present Straits of Gibraltar cut the Mediterranean Sea off from the Atlantic. The only water able to flow into the isolated marine basin...
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Rationalising geological time
The Geologic Time Spiral: A Path to the Past. Designed by Joseph Graham, William Newman, and John Stacy. Get it from http://pubs.usgs.gov/gip/2008/58/ The Système International d’Unités (SI) is the...
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Winds of Change
Altyn Tagh range at top - click for detail. Image via Wikipedia The transport of sediment by wind action is generally visualised as sand dunes of all kind of shapes. Yet shifting sand particles arm...
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Very persistent cycles
Carboniferous shale (Photo credit: tehsma) The last of five written papers in my 1967 final-year exams was, as always, set by the ‘Prof’. One question was ‘Rock and rhythm: discuss’ – it was the 60s....
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The Great Blurting
It is hard to resist curiosity when a phrase includes a superlative. Dickens knew this when he opened A Tale of Two Cities with the words, ‘It was the best of times, it was the worst of times…’. So...
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Erosion by jostling
Inca dry stone wall in Sacsayhuamán fortress, Cusco, Peru (credit: Håkan Svensson via Wikipedia) These days it is a rare thing for an entirely novel surface process to be discovered; two centuries of...
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The Time Lords of Geology
Time Lord, possibly outside the offices of the International Commission on Stratigraphy (credit: Sorcyress via Flickr) Because it is the ultimate historical discipline, the essence of geology centres...
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Not-so-light, but essential reading
In its 125th year the Geological Society of America is publishing invited reviews of central geoscience topics in its Bulletin. They seem potentially useful for both undergraduate students and...
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Assessing submarine great-earthquake statistics fails
Geologists who study turbidites assume that the distinctive graded beds from which they are constructed and a range of other textures represent flows of slurry down unstable steep slopes when submarine...
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Age calibration of Mesozoic sedimentary sequences: can it be improved?
Relative age sequences in sequences of fossiliferous sediments are frequently intricate, thanks to animal groups that evolved quickly to leave easily identifiable fossil species. Yet converting that...
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Reconstructing the structure of ancient vegetation canopies
One of the central measures used to describe modern ecosystems is the ratio of foliage area to that of the ground surface – the leaf area index (LAI) – which expresses the openness of vegetation...
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January 2015 photo of the month
Angular unconformity at Telheiro Beach, Portugal (credit: Gabriela Bruno) This image posted at Earth Science Picture of the Day would be hard to beat as the definitive angular unconformity. It shows...
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Anthropocene: what (or who) is it for?
The made-up word chrononymy could be applied to the study of the names of geological divisions and their places on the International Stratigraphic Chart. Until 2008 that was something of a slow-burner,...
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A new explanation for banded iron formations (BIFs)
The main source for iron and steel has for more than half a century been Precambrian rock characterised by intricate interlayering of silica- and iron oxide-rich sediments known as banded iron...
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Fascinating glacial feature found on Mars
Many of the vast wastes of northern Canada and Scandinavia that were ground to a paste by ice sheets during the last glacial cycle show peculiar features that buck the general glacial striation of the...
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Some cunning radiometric dating
At the end of the 1970’s I was invited by the Deputy Director of the Geological Survey of India (Southern Region) to participate in the Great Postal Symposium on the Cuddapah Basin: a sort of harbinger...
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A ‘proper’ stratigraphic view of the ‘Anthropocene’
Readers may recall my occasional rants over the years against the growing bandwagoning for an ‘Anthropocene‘ epoch at the top of the stratigraphic column. I , for one, was delighted to find in the...
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