Geology news

Rainfall Records

At https://phys.org/print446394010.html ... ancient rainfall records stretching back 550,000 years into the past show a monsoon pattern closely in step with the Ice Ages. The article is in the journal Science (May 25th 2018). During the northern hemisphere summer the tropics and sub-tropics north of the equator warm while the tropics and sub-tropics south of the equator cool. The Asian monsoon season brings rainfall to about a half of the world's population -between April and September.

Too weak to build mountains

A fascinating article at www.newgeology.us/presentation21.html ... plate tectonics is too weak to build mountains is the claim. In the 1970s it was accepted the kinematics of continental drift and sea floor spreading was successfully described by plate tectonics theory. However, very little is known about the driving mechanism of plate tectonics. In 1982 the assumption was that the generating of plate movement was understood but the driving mechanism, again, was elusive.

Volcanism in Rocks

At https://phys.org/print444408979.html ... new evidence that volcanism drove the Late Devonian extinctions. Perhaps this title should be stood up on its head - new evidence that the Late Devonian extinction event involved volcanism (with the caveat that it is not known what caused volcanism to come into play). It is otherwise an enjoyable read on an event dated 370 million years ago (one of the Big Five). It is said to have killed 80 per cent of species, including the Devonian coral reef system. It seems the presence of mercury is an indicator of volcanism.

Old Rocks

At https://phys.org/print444379905.html ... why parts of earth have hardly changed over the last 3 billion years. This title refers to ancient rocks in the western deserts of Australia (and elsewhere). Geologists are not agreed on what the earth was like prior to the formation of the plates (as in plate tectonic theory). Research published in the journal Geology (April 2018) claims earth was highly volcanically active and the evidence of a violent transition to plate tectonics (or a fractured crust) can still be seen on the surface today.

Pannotia

Supercontinent cycle theory goes back to the 1980s - see https://phys.org/print442074739.html ... Pannotia is one of five supercontinents that predate Pangea and is 'known' to have had 'profound' influence on the course of earth history and the condition of its oceans, atmosphere, and biosphere - even on the circulation of the Earth's mantle. One wonders how these things are known - rather than thought to be - but one of its adherents tells us 'we know a lot more about on what is going on between the surface and the earth's core.

Mount Etna Cone

At https://phys.org/print441599802.html ... did high sea levels in the Mediterranean create the iconic shape of Mount Etna? A study by Iain Stewart of Plymouth University has explored changes in the volcano from 130,000 years ago. It changed from a fissure type of shield volcano which came to an end around 130,000 years ago - the last interglacial period. Instead, it became an inland cluster of nested stratovolcanoes driven by a rearrangement of major faults. At the point of change there seems to have been very high sea levels in the Mediterranean and Etna was submerged.

Ruislip Bed

At Down to Earth geological group we learn that an ancient shoreline has been discovered during preliminary diggings in West London - along the line of HS2. A tunnel is being built between Northolt and Old Oak Common but the anomaly was found a little to the west, at Ruislip. The coast line is said to be subtropical - so we are going back to the Paleocene era, which followed on from the K/T boundary event. It ws found 33m below the surface, as a layer of black clay formed from what they say was a wooded and wetland environment.

Salt Shaker

At www.scientificamerican.com/article/primeval-salt-shakes-up-ideas-on-how-... ... an excellent link sent in by Jovan - primeval salt deposit shakes up ideas on how the atmosphere got its oxygen (by Nola Taylor Redd). An ancient deposite of 'sea salt' drilled from a geological basin in Russia is providing dramatic new clues on how Earth's 'early' atmosphere became oxygen rich - allowing life to evolve. This salt deposit is a billion years older than other salt deposits we are told.

German Glacial

At https://phys.org/print441019716.html ... Germany was covered by glaciers 450,000 years ago. In Britain the Anglian glaciation is dated at the same time and is most famously visible in sedimentary rocks in East Anglia. Arguments persist in how far south it reached - possibly as far as the chalk escarpment. Other theories suggest melting ice at the end of the Anglian also played a role - and this was part of the Anglian glaciation (terminal stage). One has to decide how quickly you might like the ice to melt.

Flooded Mediterranean

This story is at https://phys.org/print441004470.html ... evidence of an abrupt sea level rise 7600 years ago has been discovered in the northern Aegean. It is not immediately apparent why that number rather than 8000 years ago is used but it becomes more obvious the deeper one reads. We are told a flood of fresh water invaded the North Atlantic by a lake of glacial water (thousands of years after the last glaciation) which caused ocean currents to change etc.