Tuesday 20 December 2016

Volcanic photos

Photos of this years volcanic activity

There are lots of reviews of the year appearing - HERE is the 2016 review of volcanoes. This has some fantastic photos.

Among the photos is one of tourist activity at the Cerro Negro volcano, in Leon, Nicaragua.



I was there in 2006 when things were not quite so organised.


Thursday 15 December 2016

Turbidity Current Studied

Turbidity Current Studied


The BBC reports on a study of a turbidity current in Monterey Bay, California, using a BED (Benthic Event Detector). These were placed on the sea bed in anticipation of a turbidity current occurring. And one did on the 15th January this year.

Details of how it was done are given but few measurements. Read it on the BBC website HERE.

A visualisation of Monterey Canyon falling away from the California coast

Earth Heritage Extra 5

Exploring geological language in the Welsh landscape


Earth Heritage Extra number 5 is now out and available for download HERE. It is all about Welsh place names and their relationship to local geology. Lots of interesting stuff!

Pen y Fan, the highest of the Brecon Beacons © Joe Cornish National Trust

Tuesday 13 December 2016

Finding micrometeorites in city gutters

Searching Gutters for Stars

The Economist reports on something you could do over the holiday - start by clearing your gutters!

The link to the Economist is HERE. Because Economist articles tend to disappear with time I have copied it below


“spherules”, each around 300-400 microns in diameter (a few times the width of a human hair).

Finding micrometeorites in city gutters

An amateur enthusiast advances planetary science


ABOUT 4.6bn years ago, a spinning disc of gas and dust began to coalesce into balls of matter. The largest sphere, at the disc’s centre, collapsed under its own gravity to form the sun. Other clumps of dust, scattered around its periphery, became planets and asteroids. In planets, this dust has long-since metamorphosed into rock. But in many asteroids, it is still more or less intact. As a consequence, when asteroids collide, some of it is liberated—and a small fraction of that material eventually falls to Earth as micrometeorites. This micrometeoritic dust arrives at a rate of around six tonnes a day. Spread over Earth’s surface, that amounts to just one particle per square metre each year.

Researchers go to great lengths to gather these grains, because they can reveal details of the solar system’s composition and history. They normally collect them by dredging up ooze from the ocean bed, then sifting and filtering it to find a few precious particles, or by melting tonnes of ice from the Antarctic to see what precipitates. Those two locations have the advantage of being isolated and reasonably free of dust from industrial sources. Now, in a study just published in Geology, a group of researchers have identified about 500 micrometeorites from an unlikely source: gutter sediment from the roofs of buildings in two of Europe’s capital cities.

Enthusiastic amateur astronomers have claimed to have found cosmic dust in such urban slurry before. Professional scientists, however, tend to be sceptical of such claims, and none has been verified. Jon Larsen, a Norwegian musician, refused to be discouraged. He collected detritus from gutters in his hometown, Oslo, and also from rooftops in several cities that he visited to play jazz or to attend conferences. Micrometeorites contain magnetite, a naturally magnetic form of iron oxide, commonly known as lodestone.

Mr Larsen’s first step was therefore to pass his slurry, about 300kg of it, past a magnet and keep anything that stuck. He then examined the 30kg or so of debris that resulted under a microscope, to hunt for cosmic dust. Micrometeorites melt as they zip through Earth’s atmosphere at speeds of around 12km a second. The globules then cool into spherical grains, and the minerals of which these are composed take on a distinctive stripy appearance (see picture). An experienced eye, such as Mr Larsen’s, can thus pick them out from other particles, which tend to be jagged and lack these markings. Altogether, he found about 500 of these “spherules”, each around 300-400 microns in diameter (a few times the width of a human hair).
To confirm that the spherules were indeed micrometeorites Mr Larsen needed both expertise and more heavyweight equipment than he had at home. He therefore turned to Matthew Genge of Imperial College, London and his colleagues. They analysed 48 items from Mr Larsen’s Oslo and Paris collections under a scanning electron microscope. They were able to confirm that the composition of these matched that of micrometeorites, which tend to be rich in olivine, a greenish semi-precious gemstone. Most tellingly, Mr Larsen’s samples contained iron and nickel alloys common in micrometeorites, but rare in Earth-bound rocks because these metals oxidise rapidly.

Micrometeorites dredged from the sea may have fallen to Earth any time within the past 50,000 years or so, depending on the depth of sediment recovered. Likewise, those found in Antarctic ice may have arrived up to a million years ago. In both instances the recovery technique mixes old and new, so it is impossible to identify specimens that have arrived in the past few decades. Some of the micrometeorites Mr Larsen has collected, on the other hand, must have touched down less than six years ago, because the gutters they came from were cleaned then.

Intriguingly, these recent arrivals are more densely striped than an average specimen plucked from Antarctica or the ocean floor. That, Dr Genge says, suggests that they arrived at particularly high velocity. The speed with which they hit the atmosphere is dictated by the combined gravitational forces on them of the solar system’s planets. That they are apparently arriving faster now than in the past may be because the planets’ orbits are in slightly different positions relative to each other than they were a million years ago.

That is to be expected. Planetary orbits are elliptical, rather than circular, and their gravitational interactions with one another may cause the shapes of these ellipses to change over the years. On Earth, such changes are believed to contribute to the waxing and waning of ice ages. If micrometeorites could be collected from conventional sources in ways that recorded when they had arrived, that might aid understanding of similar changes in the orbits of other planets.
Even if this proves difficult, Dr Genge and Mr Larsen hope the guttering of the world’s roofs will prove a useful third source of micrometeorites for general study. Oscar Wilde once wrote, “We are all in the gutter, but some of us are looking at the stars.” Little did he suspect that looking in the gutter itself would also yield a little of the stuff from which stars are made. 

Monday 12 December 2016

Ice Ages - a thing of the past?!

Ice Ages and Wobbly Orbits

Here is a discussion of the effects perturbations of the earths orbit. The conclusion is that global warming may save us from an ice age. But I don't think that makes it a good thing!


Saturday 10 December 2016

Dinosaur tail in amber

A Feathered Dinosaur Tail with Primitive Plumage Trapped in Mid-Cretaceous Amber

This has appeared in several places. The original paper can be found HERE. It is in the Economist HERE. But the BBC has the most approachable version HERE.



Mike Benton on the radio

Mike Benton on the BBC World Service

I came across this and thought it was very good. Mike talks about his work in palaeontology, geology and lots of other stuff. His talk will disappear soon so download it from THIS link. You will need to save it to someplace on your computer then play it.

Friday 9 December 2016

Next Week 12th to 18th December 2016

NEXT WEEKS EVENTS


12th December to 18th December 2016


The following is an extract from Bristol Geology Calendar

More details can be found in the Calendar and on the web sites of the relevant Society or organisation.

Monday



Tuesday

19:30      WEGA Lecture
When     Tue, 13 December, 19:30 – 21:00
Where     Earth Sciences Lecture Theatre, Wills Memorial Building, Queens Road, Bristol, United Kingdom (map)
Description    Three research students - various topics

Wednesday



Thursday

19:30      Thornbury Geology Group meeting
When     Thu, 15 December, 19:30 – 20:30
Description      Thornbury Geology Group, The Chantry, Thornbury, 7.30pm, contact 01454 416882 The group is is an offshoot of Thornbury and District Museum and we welcome new members. Previous geological knowledge can be helpful but is not necessary as members are very willing to share their own knowledge with anyone keen to learn more about Earth Science. The group is loosely following a pre-recorded lecture series which is supplemented by use of other material and geological specimens. On occasions a guest speaker will talk on their specialist topic. Costs are met from attending members' monthly contributions and the group does not have membership subscriptions or a committee

Friday



Saturday



Sunday

Friday 2 December 2016

Next Week 5th to 12th December 2016

NEXT WEEKS EVENTS


28th November to 4th December 2016

The following is an extract from Bristol Geology Calendar

More details can be found in the Calendar and on the web sites of the relevant Society or organisation.

Monday

19:30
 Dave Green - Palaeontology and Evolution
WhenMon, 5 December, 19:30 – 22:30
WhereWynstones School, Stroud Road, Whaddon, Gloucester (map)
DescriptionPalaeontology and Evolution. This will be a mainly practical class, focussing on the preservation, identification and classification of fossils, and an account of the evolution of life on Earth. Starts Mon 19th September for 10 weeks (not 17th or 24th Oct), until 5th December Held at Wynstones School, Stroud Road, Whaddon, Gloucester from 7.30-9.30pm on Mondays. Cost £70 (including tea, coffee etc at breaktime!).

Tuesday

18:30
 Geological Society - Western Region
WhenTue, 6 December, 18:30 – 19:30
WhereUniversity Walk, Queen's Building, University Walk, Bristol BS8 1TR, UK (map)
DescriptionChristmas Social: Geological Quiz and Meal

Wednesday

19:30
 South Glos Mines Research Group - Talk
WhenWed, 7 December, 19:30 – 21:00
WhereMiners Institute (aka Coalpit Heath Village Hall), 214 Badmington Rd, Coalpit Heath, BS36 2QB (map)
DescriptionBristol Locomotive Builders: 1841-1958 - Dr Martin Murray and David Martin For details contact Roger Gosling tel. 01454 883607

Thursday



Friday

19:00
 Cheltenham Mineral and Geological Society
WhenFri, 9 December, 19:00 – 21:00
WhereShurdington at The Century Hall (map)
Description Sale, Quiz, and Raffle

Saturday

11:00
 South Wales Geologists' Association - Lecture
WhenSat, 10 December, 11:00 – 12:00
WhereLectures at Cardiff University are held in the Department of Earth Sciences in the "Main Building". We meet in the Earth Sciences staff room and lectures are held in Lecture Theatre 1.25. (map)
DescriptionSaturday 10th December: (Cardiff) From the depths: How cave precipitates (speleotherms) tell us about past environments and climates. Professor Ian Fairchild (Birmingham)

Sunday