Wednesday, 17 September 2014

Conditions on early Earth?

Conditions on Earth for the first 500 million years after it formed may have been surprisingly similar to the present day, complete with oceans, continents and active crustal plates.
This alternate view of Earth’s first geologic eon, called the Hadean, has gained substantial new support from the first detailed comparison of zircon crystals that formed more than 4 billion years ago with those formed contemporaneously in Iceland, which has been proposed as a possible geological analogue for early Earth.
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Friday, 12 September 2014

19th September - Two Somerset Quarries

FRIDAY 19th September
Ashen Cross Quarry, near Somerton and Bowdens Lane Quarry, Langport
Simon Carpenter and Richard Ashley
This meeting visits two working quarries. In the morning we will visit Ashen Cross Quarry where the very lowest beds of the Blue Lias are worked. Following a pub lunch in Somerton we will visit Bowdens Lane Quarry where beds in the White and Blue Lias are worked. 
Please note that this meeting is being held on a Friday, as access to these quarries cannot be obtained on the usual Saturday. Hard hats and high visibility jackets or vests are required and the party will be limited to 16 so bookings are essential. Collecting is permitted.
Meet at 10.30 am at Ashen Cross Quarry south of Somerton. Grid reference ST 495 275.

Contact Bristol NATS - Geology for details

Giant swimming dinosaur

A giant fossil, unearthed in the Sahara desert, has given scientists an unprecedented look at the largest-known carnivorous dinosaur: Spinosaurus.
The 95-million-year-old remains confirm a long-held theory: that this is the first-known swimming dinosaur. Scientists say the beast had flat, paddle-like feet and nostrils on top of its crocodilian head that would allow it to submerge with ease.
The research is published in the journal Science.
It had a long neck, a long trunk, a long tail, a 7ft (2m) sail on its back and a snout like a crocodile. When its body proportions are examined, the animal was clearly not as agile on land as other dinosaurs were, so it probably spent a substantial amount of time in the water.
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New branch of life?

A mushroom-shaped sea animal discovered off the Australian coast has defied classification in the tree of life. The tiny organism does not fit into any of the known subdivisions of the animal kingdom.
Such a situation has occurred only a handful of times in the last 100 years.
The organsims seems to have several similarities with the bizarre and enigmatic soft-bodied life forms that lived between 635 and 540 million years ago - the Ediacaran Period.
 These organisms, too, have proven difficult to categorise and some researchers have even suggested they were failed experiments in multi-cellular life.
Two new species of mushroom-shaped animals have been recognised: Dendrogramma enigmatica and Dendrogramma discoides. Measuring only a few millimetres in size, the animals consist of a flattened disc and a stalk with a mouth on the end.
More info

Friday, 5 September 2014

Latest news - Iceland's Bárðarbunga volcano

Click here to keep up to date with the latest developments

Bárðarbunga is a large central vent volcano lying underneath Iceland's 500-m thick Vatnajokull glacier in the centre of the country. It is located at the junction between the eastern and northern volcanic rift zones in the area close to where some scientists consider is the present-day location of the mantle hotspot beneath Iceland. The complex rifting means that there are probably sub-surface magmatic connections to both the Grimsvotn and Askja volcanoes.
Bárðarbunga has had about 300-400 eruptions during the past 10,000 years including 23 eruptions in historic times with the last one having occurred in 1910. Worryingly, it produced the largest known lava flow during the past 10,000 years on earth (more than 21 cubic kilometers of volume). The lava was erupted from the Veidivötn fissure system and travelled more than 100 km to the south coast.
Since the beginning of August the  Icelandic Meteorological Office (IMO) has been keeping a close eye on activities in the Bárðarbunga area. They were particularly concerned that there may be a major sub-glacial eruption (jökulhlaup) that had
the potential to repeat the historic eruption referred to above.
Recent activity:-
Initially, there were small ash eruptions from a point close to the old Bárðarbunga vent and then major magma movement was detected along a 6 km rift that has taken the activity away from the glacier and towards the Askja volcano. Meanwhile, large circular depressions in the glacier have been detected, indicating that there is still some activity further to the south.
On August 30th and 31st a classic lava curtain eruption began along a section of the rift where a shallow dyke had been emplaced. Basaltic lava and a little tephra has been erupted, well away from the glacier.
So far there has been no major disruption to aviation and the eruption remains of the effusive lava type.
Seismic events:-
Several seismic events have occurred around the Bárðarbunga caldera rim of magnitudes around 4.5.
If this goes according to the pattern of many previous Icelandic eruptions, one of the following may occur:-
• eruption continues at the present level for a month or so
• the eruption dies down and then ceases with the basalt cooling
• the eruption becomes concentrated on a single point which could be Askja or another location
• none of the above scenarios may apply!