Friday, 29 May 2020

Down to Earth Extra - June 2020


DOWN TO EARTH EXTRA - June 2020

The latest edition is available HERE

Or you can read it below.



Wednesday, 27 May 2020

Strong Poison - in the well

Strong Poison - in the Well

I came across Lord Peter Wimsey and arsenic in Dorothy L. Sayers novel "Strong Poison" which I strongly recommend - the novel, not the arsenic. THIS ARTICLE is much less entertaining but very informative. 

What started as a good thing became a tragedy. Providing water from drilled wells stopped people becoming ill from gastro-intestinal infections. But, over time, signs of arsenicosis appeared. 

Why arsenic got into the water is far from obvious. The article explains the complex chemistry involved - goethite (containing Fe-3 and other stuff including arsenic) in reducing conditions breaks down to Fe-2 and releases its arsenic. Fascinating and deadly chemistry!

Well worth reading and here is a map showing where it is not safe to drink the well water.

Modelled global probability of arsenic concentration in groundwater exceeding 10 μg l-1. Click to display a larger map in a separate browser tab. (credit: Podgorski & Berg; Fig 2A, with enhanced colour)

Mary Anning - her story in an unusual form

Mary Anning - Her Story in an Unusual Form

I came across THIS and thought most of you would like it. Turn up your loudspeakers



Saturday, 23 May 2020

Edenville Dam Breach

Edenville Dam Breach

One of my favourite blogs (The Landslide Blog) has 3 very interesting articles about the the breaching of this dam in Michigan USA.
The FIRST gives the news and the information that its licence had been withdrawn.

The SECOND has a video showing the failure of the dam. It is this which drew my attention.



And the THIRD discusses what happened and the consequences. The author suggest many similar dams will need to be looked at as global warming is changing weather patterns and higher rainfall may be greater than many dams can cope with. 

Tuesday, 19 May 2020

Martian Mud Flows

Martian Mud Flows

There are features on Mars that could be mud flows or lava flows. Until this is settled, perhaps (but unlikely) by a geologist with a hammer, speculation continues. And to provide some facts for the speculation we have THIS ARTICLE (brought to my attention by a correspondent) which describes experiments which look at how mud acts in a Martian environment.

In the low pressure of Mars's atmosphere mud acts like pahoehoe lava and looks like it also.

The initial article can be found HERE.

A suggested mud flow on Mars spied from orbit. A geologist on the ground could tell for sure.

Friday, 15 May 2020

Has Metamorphism Always been the Same?

Has Metamorphism Always been the Same?

THIS VERY INTERESTING ARTICLE follows the debate whether metamorphism has always been the same. The minerals in a metamorphic rock can tell you its temperature and pressure history. 

It has long been suspected that the average T/P conditions revealed by metamorphic rocks have varied over geological time, this article discusses A RECENT PAPER which tries to put some numbers to this speculation. And also A DISCUSSION of the paper.

At the heart of the discussion is thermobarometric data - derived from mineral assemblages which indicate the temperature and pressure at which they were formed. The 564 data points are, as one would expect, not evenly scattered through time. And clusters of data points show a wide scatter of T/P. 

But the original authors manage to extract a smooth curve showing that T/P lowered with time and suggest this is linked to the development of modern plate tectonics. 

The author of the discussion thinks the lowering of P/T is due to a fall in mantle temperature. 

All this is far above my competence - I leave you to read the articles and decide for yourselves!


The latest division in pressure-temperature space of different styles of metamorphism (colours) and the main mineral equilibria (dashed lines) that define them. Note the three T/P lines. Did early rocks follow the 30℃/km line and later ones the 10℃/km line? - very roughly speaking and using averages and with all sorts of caveats!

Peter Cawood’s ‘take’ on the relationship between tectonic development and other important variables in the Earth-system with the estimate by Brown et al. of the mean metamorphic T/P (‘thermobaric’) variation through Earth history



Footnotes May 2020

Footnotes May 2020

Footnotes, the newsletter of the Wessex Branch of the Open University Geological Society, is available for download HERE.

Remember

And, keeping the correct distance apart, read it below!



Sunday, 3 May 2020

Stonechat Magazine

Stonechat Magazine

A correspondent has brought this magazine of the Horsham Geological Field Club to my notice and now I bring it to yours! 

If I edited a magazine as good as this I would be very proud! Read it and Marvel!

You can get it HERE. Or read it below.

Thursday, 30 April 2020

Down to Earth Extra - May 2020

Down to Earth Extra - May 2020

The latest edition was sent to me in 2 parts. Get Part 1 HERE and Part 2 HERE.

I have combined the parts and you can get the complete version HERE.

Or you can read it below.



Tuesday, 28 April 2020

Geologic Map of the Moon

Geologic Map of the Moon

A frequent correspondent has sent me THIS LINK. It introduces a newly released Geologic Map of the Moon produced by NASA. 

NASA introduces it HERE. The download is a little slow but you can get it, in all its glory, HERE. Also, below.




Monday, 20 April 2020

Dinosaurs on Selsey Common!

Dinosaurs on Selsey Common!

Another correspondent has brought this interesting sight near Stroud to my attention. The pictures speak for themselves.

LATER
This post has created some controversy. Yet another correspondent writes:-
--------------------------------------------
I love getting the updates and I like seeing art and science promoted but I have to say I am incensed by the latest offering 

Placing stones on grass seems set to become a craze and publicising it without a severe rebuke is unacceptable and can only fuel this act of utter thoughtless vandalism and conservation evil.

Environmental gems such as fescue and bent grasslands have taken millennia to establish and one thoughtless  (mindless) act will destroy the delicate grasses forever - eliminating the wild flowers which many butterflies depend upon as well as other less obvious problems. Tourists will exacerbate the problem as their footprints compact the soil making it impossible for these delicate grasses to survive. Not to mention the animals and plants living on or under the stones which will also lose their homes or die. 

I have seen stones placed onto heathland and downland before but never on this scale.  Please please let try to nip this illegal and damaging stupidity asap.

At the very least make it clear anyone making such art has a duty to restore nature, after a few minutes  - ensuring the stones are replaced EXACTLY where they were found and right way up Like the sand beach artists washed by the tide


I am sorry I am not a kill joy but the stupidity of our species knows no bounds. 
-------------------------------------------------
I have received a reply from the original correspondent.
----------------------------------------------------------
I’m always amazed at the comments made by the narrower minded ‘conservationists’ who are only concerned with their own interest and point of view.   Totally ignoring the impact that all animals make on the planet - including homo sapiens!    Their comments give much cause for amusement though so they are not all bad...

Bearing in mind that this is in an old (human made) quarry where the locals for generations have created pictures and written their names in stone I can’t see the problem.     Especially as the quarry is surrounded by plenty of ‘natural’ grassland.


Keep up your good work of informing us all of events.
-----------------------------------------------------------
This blog is not the place for continuing this controversy, so it is now closed.








Saturday, 18 April 2020

Iceland Volcanoes - all the information

Information on Iceland's Volcanoes

A correspondent has sent me THIS LINK. It is a catalogue of all of Iceland's volcanoes and the amount of information is astonishing. Well worth a browse!



Thursday, 16 April 2020

Dinosaurs Overhead Underground

Dinosaurs Overhead Underground

500 metres below the Causse Méjean karst plateau, in the Castelbouc cave on the River Tarn, a scientist on a caving trip spotted dinosaur footprints on the roof of a rather large cavity. 

A scientist on a caving trip happened to spot dinosaur tracks in the ceiling of Castelbouc Cave in France. Credit: Jean-David Moreau et al./J. Vertebr. Paleontol.
The result is THIS ARTICLE based on THIS JOURNAL ARTICLE (you need to pay to see more than the abstract, unfortunately).

It seems that access is difficult and not for the likes of me, but it is reported that the tracks were made by some very large beastie, presumed to be titanosauriforms. Indeed the authors erect the new ichnogenus and ichnospecies Occitanopodus gandi, igen. et isp. nov. I suppose all the abbreviations mean something to the people professionally concerned with the matter.

Tuesday, 14 April 2020

A (Virtual) Geological Trip to the Karoo

A (Virtual) Geological Trip to the Karoo

Yet another correspondent forwarded me THIS LINK to a very interesting article mostly about Karoo dolerites and included three of her own photos. 

The Karoo is the "Fly Over" part of South Africa, between Cape Town and Johannesburg. Much of it is flat and boring but there are occasional spectacular, flat topped mountains and these are the result of intrusions of dolerite sills and dykes.

A particular emphasis of the article is the hope that dolerite intrusion has reduced the attractiveness of the area for companies looking to exploit shale gas. 

But my correspondents photos are the best for appreciating the dolerites of the Karoo.


Thaba Thabo, near Fouriesburg in the Freestate, near the Lesotho border.  A vertical dyke in sandstones has weathered out more than the baked margins - the hornfels.  Note that this is close to the contact with the overlying Drakensberg lavas, so it may have been a feeder dyke.
A thick dolerite body, which is climbing up section but nearer to a sill than a dyke., capping a hill near Harrismith in the North-east Freestate.

Top is a sill and another intrusion which not quite a dyke or a sill, which appears to have displaced the sandstone layers and bent them downwards, at the right.  There is a small dyklet feeding in to it along the fracture. On the road from Beaufort West to Calvinia in the Northern Cape.





Ordnance Survey - Things to do at home

Ordnance Survey - Things to do at Home

Another correspondent suggested this might be useful.






Thank goodness the step up challenge is over!


Severn Bore

Drone on the Severn Bore

A correspondent directed me to watch this footage of the Severn Bore as there were no surfers present! It was filmed from a drone and you can see it HERE or below. The reason there are no surfers is because of the Coronavirus lockdown. I suppose that is a positive.



Saturday, 11 April 2020

Oxford Geoheritage Virtual Conference

Oxford Geoheritage Virtual Conference

I know a lot of you are interested in our geoheritage in one form or another. Because of COVID-19 many conferences on the subject have been cancelled or postponed. So, of course, the answer is to have a virtual conference. This has many disadvantages - you cannot have face to face conversation or travel to exotic locations - but at least the conference can take place and you do not need to get out of bed! (or your preferred place for being online.)

You can read all about one being organised by Oxford Museum of Natural History HERE. If you want to submit a paper the abstract has to be in by 29th April. If you want to attend (virtually) you have to register by 18th May. And the conference starts on 25th May.

This sounds very good for the person with a casual interest - no cost for travel, accommodation, food etc.

Monday, 6 April 2020

Coronavirus - Seismologists Notice Something

Coronavirus - Seismologists Notice Something

A correspondent brought THIS and THIS to my attention. They both record that lockdowns imposed as a result of the Coronavirus outbreak have reduced the amount of seismic noise which reduces the sensitivity of seismometers located in urban areas. Obviously not earth shaking news but still very interesting!


Saturday, 4 April 2020

Footnotes in a Time of Virus

Footnotes in a Time of Virus

The Wessex Group of the OUGS is one of the most active and this continues in the present lockdown. 

For all of you looking for something geological to do they have produced a special edition of Footnotes, their rather well produced Newsletter.

You can get it HERE, or read it below.


Wednesday, 1 April 2020

Slow Earthquakes

Slow Earthquakes

I had heard of such things but did not know much about them, so I was interested in reading THIS ARTICLE. After reading the article I realise that calling them earthquakes is dramatising something with no drama at all! 

An earthquake releases a lot of energy very quickly. A "slow earthquake" can release the same amount of energy but over a period of months or even longer. Is a slow earthquake somewhere between rocks moving steadily and moving in earthquakes? Can a slow earthquake trigger a catastrophic one nearby?

What makes an area have slow earthquakes rather than a catastrophic one? The author (from Cardiff) has been working in New Zealand where the Hikurangi subduction zone off the south eastern coast of the North Island demonstrates slow earth earthquakes in a conveniently shallow and accessible place. 

He hypothesises that the very variable seafloor rocks and sediments may have something to do with it. Also the presence of seamounts, pressurised fluids decreasing frictional resistance, seafloor roughness and other things might be involved. Obviously we are in a phase of looking for a cause.




Out and About - on Mars

Out and About - on Mars

A correspondent emailed me THIS LINK and it is wonderful. I make a lot of panoramas with my photos but they pale in comparison (on at least two levels - quality and location!) with this one. Look on it and wonder!



Wednesday, 25 March 2020

DOWN TO EARTH EXTRA - April 2020


DOWN TO EARTH EXTRA - April 2020


You can get the latest edition HERE




At this Moment of Crisis........

At this Moment of Crisis........

Several correspondents have brought the following to my notice.


I think it originated on EPOD, which contains much of interest.

Diamonds Make a Craton Bigger

Baffin Island Kimberlites and the North Atlantic Craton

A correspondent has brought THIS ARTICLE to my attention. Researchers working on kimberlites in southern Baffin Island found that wall rocks brought to the surface by the kimberlites bore evidence that they were part of the North Atlantic Craton. 

This increases the craton's size by 10%. You can find more from HERE, and for the truly dedicated HERE. If you are dedicated and solvent and want to investigate further look HERE

Geologists studying rock samples from Baffin Island find lost fragment of continent. Photo: istock.

Saturday, 21 March 2020

23rd to 29th March 2020


NEXT WEEKS EVENTS


23rd to 29th March 2020


THE FOLLOWING IS AN EXTRACT FROM BRISTOL AND WEST COUNTRY GEOLOGY CALENDARS


MORE DETAILS CAN BE FOUND IN THE BRISTOL AND THE WEST COUNTRY CALENDARS AND ON THE WEB SITES OF THE RELEVANT SOCIETY OR ORGANISATION.


Nothing Happening!

Blame the Virus
and wash your hands!


If you know of any events, let me know.



Saturday, 14 March 2020

16th to 22nd March 2020



NEXT WEEKS EVENTS

16th to 22nd March 2020


THE FOLLOWING IS AN EXTRACT FROM BRISTOL AND WEST COUNTRY GEOLOGY CALENDARS

MORE DETAILS CAN BE FOUND IN THE BRISTOL AND THE WEST COUNTRY CALENDARS AND ON THE WEB SITES OF THE RELEVANT SOCIETY OR ORGANISATION.


MONDAY 16TH

Geostudies Lecture Course - Germany
When
Mon, 16 March, 19:30 – 21:30
Where
Wynstones School, Stroud Road, Whaddon, Gloucester (map)
Description
The Geology of Germany 

 Monday 13th for 10 weeks (not 17th Feb) until 23rd  March. Held at Wynstones School, Stroud Road, Whaddon, Gloucester from 7.30 - 9.30pm on Mondays. 

Like Britain, Germany consists of a number of exotic Terranes, derived from different continents and amalgamated together by plate tectonic collisions. Northern Germany is part of Avalonia, which amalgamated with the East European Craton (Baltica) along the Tornquist suture in the east. A great deal of this area is plastered by thick Quaternary glacial sediments. 

Central Germany is part of Armorica, which collided with the north during the Variscan orogeny. There is, in places, thick Mesozoic unconformable cover. The extreme south is part of the Alpine orogeny, but its effects were transmitted northwards to affect and reactivate older structures. There was extensive volcanic activity during the Tertiary, and some famous asteroid impact sites. 

Cost £75
-----------------------------------------------

Teme Valley G S - Lecture
When
Mon, 16 March, 19:30 – 21:00
Where
Martley Memorial Hall B4197 by Sports Ground (map)
Description
Richard Edwards, The Japanese Island Arc:Perspectives on the Malvern Complex and Warren House Formation  

tuesday 17th


wednesday 18th


thursday 19th

Thornbury Geology Group, 7.30pm, The Chantry, Thornbury
When
Thu, 19 March, 19:00 – 21:30
Description
Thornbury Geology Group, 7.30pm at The Chantry, Thornbury, and every 3rd Thursday in the month.  

friday 20th


saturday 21st

South Wales G A - Lecture and AGM
When
Sat, 21 March, 10:30 – 12:30
Where
Lectures at University of Wales Swansea are held in the department of Geography in the Wallace building. We meet on the landing area inside the main entrance to the building for refreshments with lectures in the main lecture theatre. (map)
Description
AGM and retiring President's Address


sunday 22nd