Thursday, 22 April 2021

Deep Sea Volcanoes - What Do We Know - Not Much

Deep Sea Volcanoes - What Do We Know - Not Much

A correspondent and I both spotted THIS ARTICLE today, and we both thought it was worth putting on the blog.

Most of the Earth's volcanic activity occurs under the sea but this was not realised until the 1950's and even today very little is known about it - mid-ocean ridges and black smokers. 

It was thought that deep-sea eruptions were rather boring. In particular explosive eruptions would not happen as the water pressure would prevent the possibility of steam. But now the presence of tephra tells us that explosive eruptions do occur - caused by expanding bubbles of carbon dioxide.

Megaplumes of hydrothermal fluids in the ocean have been detected, up to and over 100 cubic kilometres in volume. This is a lot of Olympic sized swimming pools!

Mapping of volcanic ash deposits suggests that the ash dispersal is caused by high energy plumes. The amounts of energy required are huge and the plumes form quickly over seafloor eruptions and are formed, not from the energy of a lava flow - these would be too small - but by the expulsion of hot fluids (hotter than 300℃) from the sea bed. The eruption of the lava drives the expulsion of a much larger volume of  hydrothermal fluid.

The authors propose that a side effect of these plumes is the dispersal of life across the Earth. And as life may have started in the extremophile communities, they may have been an influence on the origin of life on Earth.


Friday, 16 April 2021

Did India Speed-Up to Create the Himalayas? - NO!

Did India Speed-Up to Create the Himalayas? - NO! 

A correspondent has sent me THIS LINK (and its ACADEMIC PAPER FOUNDATION) for which I am very grateful.

It was long thought India, on its journey from the edge of Africa to the site of its crashing into Eurasia, to create the Himalayas, sped up. The reason for the speed-up was that it "slid off" the dome caused by the rising of the Reunion mantle plume.

This seemed too simple for the authors of the academic paper. Their studies showed that there was a speed-up, not only in India's travels but, at the same time, the separations of Africa / Antarctica, Africa / South America and Antarctica / South America all sped up.

The time period was at the boundary between the Cretaceous and the Tertiary - the chrons C28-C29 to the aficionados of the period. They conclude that this period was actually 70% longer than previously thought.

And the result is that Plate Tectonics, once again follows the rules.

Ubiquitous 67 Ma acceleration in model divergence rates for five plate pairs in Indo-Atlantic circuit (see text for model references). Light-gray bars—magnetic reversal time scale of Gradstein et al. (2012), where C25n–C32n.2—magnetic chrons. Red hatching—Deccan volcanism. 


Sunday, 11 April 2021

Another Icelandic Volcano Video

Another Icelandic Volcano Video 

I came across THIS VIDEO on a photographic site. It shows some of the most spectacular video I have seen. It was shot almost entirely using drones. You will not be surprised that the photographer ended up with a somewhat melted drone! Watch the video on the largest screen you can.


Tuesday, 6 April 2021

Tungsten Isotopes and the Beginning of Plate Tectonics

Tungsten Isotopes and the Beginning of Plate Tectonics 

Super correspondent also sent the link to THIS ARTICLE. It describes, in a remarkably simple way, the use of tungsten isotope tungsten-182 to determine the start of plate tectonics about 3.2 billion years ago. Give or take 100 million years.

Tungsten-182 is formed from the radio-active decay of hafnium-182 within 60 million years of the formation of the solar system. Find a lot of tungsten-182 compared to the other tungsten isotopes and the rock concerned had not been churned by subduction.

So find rocks to which nothing much has happened in the last few billion years. That, of course, means the Yilgarn of Western Australia where nothing much geological happens.

All this sounds rather straightforward, but actually doing it is not easy - neither in the bush or in the laboratory. The article tells the story well.


Collecting specimens in the Yilgarn.

An Unusual Volcano - and Why it Matters

An Unusual Volcano - and Why it Matters 

A super correspondent brought THIS (and the next item) to my notice - thank you very much!!!

In January 2015, WEGA had a lecture by Dr. James Hammond, one of the geologists mentioned in the video, about the Mt Paektu volcano on the borders of China and North Korea. I remember his lecture as being very interesting. Obviously more work has been done on the data and the video goes into a lot of detail concerning the fate of the Pacific Plate as it descends into the mantle.


The video goes into what could be abstruse minutia but does it in an informative manner. Well worth watching.

If you spot something which you think should be on the blog, send me the link and you too could be a super correspondent!


Saturday, 3 April 2021

Jurassic Coast Geology Cruises

Jurassic Coast Geology Cruises 

In July 2007 WEGA took part in a Geology Cruise from Exmouth to (almost) Lyme Regis and it was a great success aided by magnificent weather and an expert commentary from Richard Scrivener, at that time, the Geological Survey's man in Exeter.

And recently I came across a reference which told me that these cruises are continuing. I do not know who is doing the commentary (if there is one) and the exact route but you can book for the 29th of June and the 13th September HERE.

The scenery is lovely - not all the rocks are Jurassic!

DSC06308


Our cruise in 2007

Friday, 2 April 2021

First Animals at the Oxford University Museum of Natural History

First Animals at the Oxford University Museum of Natural History 


Some of you must know about THIS WONDERFUL SERIES OF VIDEOS but I only came across it by accident. It discusses, in great detail, the Cambrian Explosion.

My favourite (so far) is THIS ONE by Paul Smith, which among much else, describes looking for fossils in the very north of Greenland. But every thing I have seen so far is excellent and very professional - in the best sense!



Cambrian Ocean Scene

Thursday, 1 April 2021

Stonechat - April 2021

Stonechat - April 2021 

Another edition of this excellent club Magazine has appeared. You can get it HERE.

And you can read it below. There is a good article about Svalbard which contains (with much else) this:-




Saturday, 27 March 2021

Icelandic Volcano Videos

Icelandic Volcano Videos 

There are a plethora of videos of the ongoing eruption in Iceland. But, as yet, I have not seen one by a geologist. The video below has very little geologic commentary but shows the "communal" aspects of the eruption. But there is some spectacular footage amidst the guff.




The next video is much more professional and even has some talking heads, some mentioning the dangers. There are even more videos all showing the same stuff if you go to youtube.com and search for "iceland volcano".


Down to Earth Extra - April 2021

Down to Earth Extra - April 2021 

The latest edition of Down to Earth Extra is HERE.

And you can read it below.



Saturday, 20 March 2021

As Expected, Icelandic Volcano Erupts

As Expected, Icelandic Volcano Erupts 

On 5th March I blogged that a volcano near Reykjavik showed signs of erupting.

And it has! There is mention of it everywhere but what I enjoyed most was a quote in the Financial Times:-

“I can see the glowing red sky from my window,” said Rannveig Gudmundsdottir, a resident in the town of Grindavik, only 8km from the eruption. “Everyone here is getting into their cars to drive up there,” she said."

As I said on the 5th March, Iceland is one of the best places to be if a local volcano erupts.


Thursday, 18 March 2021

The Great Dying

 The Great Dying

A correspondent has brought THIS ARTICLE to my attention. The author looked at food webs over the Permian - Triassic period in North China. There were three extinction events over the period and their relative severity was measured.

The events were the Guadalupian-Lopingian extinction event (259.1 million years ago), the End-Permian mass extinction (251.9 million years ago) and the Triassic-Jurassic extinction event (201.3 million years ago). And the conclusion reached was that the End Permian was the most serious one. 

It took 10 million years for life to recover from that one, much less for the others. The difference was, as Mike Benton explains, 

"We found that the end-Permian event was exceptional in two ways, First, the collapse in diversity was much more severe, whereas in the other two mass extinctions there had been low-stability ecosystems before the final collapse. And second, it took a very long time for ecosystems to recover, maybe 10 million years or more, whereas recovery was rapid after the other two crises."

The article is based on a research paper in "Proceedings of the Royal Society B" reading of which gives one a measure of the amount of work which went into this research.

Very interesting stuff and I get to show a picture of a sabre-toothed gorgonopsian!


The plant-eating pareiasaurs were preyed on by sabre-toothed gorgonopsians. Both groups died out during the end-Permian mass extinction, or "The Great Dying." Credit: © Xiaochong Guo

Tuesday, 16 March 2021

Sinkholes

Sinkholes 

For every 0.1°C rise in temperature, the number of sinkholes increases by 1%-3%. That is the statistic which intrigued me when I read THIS ARTICLE.

Sinkholes occur naturally when minerals in the Earth beneath us dissolve in rainwater, forming cavities. The sinkhole appears when rainwater loosens the soils around the cavities enough for the ground to fall in.

But this has been made much more common by human activity. The biggest culprit being, of course, climate change. This often leads to heavier rainfall and the subsequent sinkholes.

The article goes into a lot of detail, especially about a particularly large sinkhole in Naples. Incidentally there is a link (copied HERE) to underground Naples - next time Dave Green goes to Naples he should follow this up!

The author describes current means of strengthening ground which can cause rather than ameliorate danger. And mentions research into more novel means of ground engineering.


 Rescuing a farmer and his quad-bike from a sinkhole in Cumbria. 
Pic: Twitter/@CumbriaFire

Monday, 15 March 2021

The, Not So, Good Old Days

The, Not So, Good Old Days 

As geologists we know that the Earth changes over time. If it didn't geology would not exist! But THIS ARTICLE gives some indication as to how much it has changed.
The author, a geochemist at Cambridge, describes her conclusions from analysing very old rocks from South West Greenland.

And she concludes that for a long period the Earth did not have a solid crust - it was an ocean of molten magma. The article describes the conclusions and tells us that these came from measuring isotopes of iron. You can read all about these in THIS PAPER. Some of you may understand it!

An important mineral in the paper, and the lower mantle, is bridgmanite - a mineral with which I was not familiar. Apparently it is what I knew as perovskite. Perovskite is a structure rather than a mineral and a mineral can only have a name if it exists on the surface of the Earth. Then it was found in a meteorite and it could be named! You can read all about it HERE.


The Earth is now composed of the inner core, the outer core, the lower mantle, the upper mantle, and the crust. AlexLMX/Shutterstock.
The very early Earth was not like this at all!

Saturday, 13 March 2021

Global Warming Gone Mad!

Global Warming Gone Mad! 

Very little to do with geology, very little to do with the Earth but still very interesting!

THIS ARTICLE tell of the hottest planet ever found - Kelt-9 b. So hot that metals, in vapour form, are in the atmosphere! 

To get a planet that hot, start with a gas giant and move it, probably by collisions, into an orbit around its star much closer than that of Mercury round our Sun. It helps if the star is twice as hot as the Sun. And you get temperatures of 5,000°K.

The data which led to these conclusions came from the Hubble Space Telescope and is publicly available. Two methods of finding the composition of the atmosphere were used. In the transit method the light of the star passing through the planets atmosphere is used. In the eclipse method when the planet goes behind its star, its (very small) contribution to the total light is removed and its light contribution can be determined. I suspect some this process is a bit beyond my powers!

The authors look forward to the launch of other space telescopes - NASA's James Webb Space Telescope and the European Space Agency's Ariel Space Mission - which will be able to extend the study of exoplanets.


Artist’s impression of Kelt-9 b orbiting its parent star. NASA/JPL-Caltech

Tuesday, 9 March 2021

Keep the Geol. Soc. in Burlington House!

Keep the Geol. Soc. in Burlington House!

You may have seen this reported in the papers. See below. 

It has always seemed to me that it was appropriate that learned societies should be at a prestigious address. For over a century they were there rent free. The proposed rent increases would be ruinous for the societies, chicken feed for the government.

Who would occupy the place? I presume it is listed. It would be expensive, but convenient for Fortnum and Mason and Bond Street. Possible occupiers are few and I doubt that they would be better for society than the present residents.

Read what Jean Sippy has to write below.

------------------------------------

Dear Members,

 
You may already know the following news of  Burlington House where the Geological Society and other learned societies are based. This affects us directly as The Geological Association, of which we are a Local Group, is also based within the Geological Society and we have monthly and other meetings there and also occupy offices in the basement.

 
“Burlington House Under Threat

Rents of the Learned Societies in Burlington House have risen 3000% since 2012 and are set to bankrupt them.  Burlington House was originally conceived to bring together major cultural and scientific learned societies.  Unless they can come to a reasonable agreement on affordable rents with the government, they will have to find alternative accommodation that will divert their precious resources.  The Geological Society, the Linnean Society, the Astronomical Society and the Antiquarian Society are all under threat.  An article in the Observer on Sunday 28 February highlighted the problem: www.theguardian.com/science/2021/feb/28/under-threat-the-birthplace-of-darwins-historic-theory, and the Geological Society of London launched a campaign with the other societies to reverse the rent rises. Conservative MP Tim Loughton is leading a cross-party group of MPs trying to secure a long-term deal for the societies with the Ministry of Housing, Communities and Local Government. The Geological Society outline ways in which members of the public can help with the campaign and anyone interested should follow the link: www.geolsoc.org.uk/burlingtonhouse.”

------------------------------------

The following are extracts from the Geological Society’s web site.

 

“The Geological Society moved to Burlington House in 1874 by agreement with the Government of the day. Up until the first lease period (2005) the Society’s Burlington House ‘apartments’ bore no rental costs or external upkeep responsibilities.

In 2004, HM Government challenged in the High Court the legal basis of occupation of Burlington House by the five learned societies, including the Society of Antiquaries, Royal Society of Chemistry, Royal Astronomical Society and Linnean Society. The case concluded in 2005 with court-directed, fast track mediation under which the societies agreed terms of occupation under new leases. With effect from January 2005, after a 2-year rent-free period, rent was initially minimal.

Following a 2012 lease valuation resulting in an appreciable rent increase, a collective arbitration was initiated reflecting concerns around the valuation process and comparators being employed. In late 2016 the arbitrator found comprehensively in favour of the Landlord, concluding that the mechanism for the determination of rental value was being followed properly and the valuations used were not wholly unrealistic or negligent. Given the absence of independent valuation, the tenants were not entitled to dispute matters of valuation judgment exercised by the Landlord. 

Last year the rent for the Geological Society was £217,000 and under the current agreement rents will rise by c. 8% p.a. for at least the next five years. This means a 50% rise in five years and a 100% rise in the next nine years. 

The Society is asking the Government to recognise the value of having the learned societies and historically important libraries, archives and collections situated at Burlington House. We are asking Government to work with us to agree an affordable long-term arrangement for the Society to remain at its home, ensure that we and our fellow societies continue to deliver value to the UK economy and society.

Government originally brought the Society to Burlington House under a bespoke arrangement which has delivered immense public value as a hub of cultural and scientific discovery. Historical circumstance places a duty upon the Government to find a workable, affordable arrangement which recognises the value of the Society’s activities, its library and collections to the nation. 

If an affordable arrangement cannot be agreed, we will have no choice but to seek alternative accommodation. This will divert crucial funds from our core activities, adversely impacting our science, policy, education, outreach and professional standards work .

We ask those in support of the Society remaining at Burlington House to write to their MP to ask for an affordable, long-term agreement to be put in place, and to help raise further awareness of the campaign by retweeting @GeolSoc, and by using the hashtag #SupportGSL.”

 

Jean Sippy

Hon. Secretary

Harrow and Hillingdon Geological Society

www.hhgs.org.uk

Tel: 020 8422 1859

------------------------------------

Friday, 5 March 2021

North West Highlands Geoparks Zoom Lectures

North West Highlands Geoparks Zoom Lectures 

As a supporter of the North West Highlands Geopark i came across this Zoom Lecture which is fascinating. It is by a Bristol PhD - Frankie Dunn, now at Oxford Museum, talking about the Cambrian Explosion and what can be seen of it in the Cambrian of the Assynt area. She is introduced by Pete Harrison, whom many of us know from WEGA's excursion in April/May 2019. 

You can listen and watch the lecture HERE. A very interesting lecture and the audience includes a magnificent beard and moustache wearer. Absorbing lecture but I suspect not all the listeners were awake at the end!

They have an stimulating programme arranged. You can see it HERE.


Iceland Eruption Coming?

Iceland Eruption Coming? 

THIS ARTICLE tells us that there has been many small earthquakes beneath the Reykjanes Peninsula, west of Reykjavik. There are fears that the Krysuvik volcanic system might erupt. You can read all about the volcanic area HERE.

As the article says, Iceland is one of the best places to be if a local volcano erupts. You need to be very unlucky to be harmed by an Icelandic volcano erupting - unless you are an air traveller!

This is something to watch - it might get interesting.


Present day activity at Krysuvik

Wednesday, 3 March 2021

Down to Earth Extra - March 2021

 Down to Earth Extra - March 2021

The latest edition of Down to Earth Extra is HERE.

And you can read it below.


Tuesday, 23 February 2021

Chalk

 Chalk

HERE is a surprisingly good article about chalk. When I started it I thought it was going to be a fact-light piece of puffery, but it soon became apparent that lots of research had gone into the item. But its learning is worn lightly and it is a pleasure to read.

Well worth your time!



Monday, 22 February 2021

Events Poster

West Midlands Regional Group of the Geological Society - events poster 

I came across this poster which seems to have lots of goodies advertised. You can get it HERE or look at a rather too small to read version below.


Saturday, 20 February 2021

Magnetic Pole Reversal - the Impact

Magnetic Pole Reversal - the Impact

Here is something else to worry about! We all know that every so often the earths magnetic field reverses - the North Magnetic Pole switches to attracting the south pole of a compass. The last reversal was the Laschamp Event - see HERE - which occurred about 42,000 years ago.

THIS ARTICLE describes the use of a New Zealand kauri tree, of the relevant age, preserved in a peat bog, to examine the effect of the reversal. And it was found that there was a spike in atmospheric radiocarbon levels.

And there was a lot else going on at the same time. 
  • Tropical Pacific rain belts and the Southern Ocean westerly winds abruptly shifted 
  • Giant kangaroos and giant wombats went extinct
  • The vast Laurentide Ice Sheet rapidly grew across the eastern US and Canada
  • The Neanderthals spiralled into extinction
  • High UV levels caused early humans to seek shelter in caves, explaining the apparent sudden flowering of cave art across the world 42,000 years ago.
  • Lots of other things!
Are they all connected? No doubt many people will be looking at this. 

Remember The Hitchhiker's Guide to the Galaxy? The answer to life, the universe and everything was 42. So Douglas Adams knew more than he thought. All the stuff happening 42,000 years ago has been given the name "The Adams Event".



Sunday, 14 February 2021

Stonehenge and the Geochemistry of the Bluestones

Stonehenge and the Geochemistry of the Bluestones 

Last Friday I watched a fascinating programme about the bluestones of Stonehenge. A lot of it was digging holes in the rain (archaeology), but there was quite a lot about using geochemistry to find the exact origin of the bluestones. It is well worth watching - even the archaeology is interesting!

You can watch it from THIS LINK.



Saturday, 6 February 2021

Down to Earth Extra - February 2021

Down to Earth Extra - February 2021

The latest edition of Down to Earth Extra is HERE.

And you can read it below.



Thursday, 4 February 2021

Ammonite Unshelled!

 Ammonite Unshelled!

THIS ARTICLE in the New York Times refers to THIS ACADEMIC ARTICLE and concerns an ammonite fossilized without its shell. Once I got over my bemusement - how do you recognise an ammonite if it doesn't look like an ammonite?! - I found the articles very interesting, especially how did it come to be out of its shell.


Soft parts of Subplanites sp. with a Strigogranulaptychus sp. from the early Tithonian of Wintershof near Eichstätt (Germany); SMNS 70,610. a Photo taken under white light. b Line drawing of the structures visible in the white light-photo (a) with possible interpretations

The Times tells us that ammonitologists (?) are excited. It took some time to give names to the various bits which look like smears to me - but then I am not an ammonitologist! There are not much written about the soft parts of ammonites, comparisons have to be made with living relatives such as Nautilus pompilius, but the authors are able to give names to all the bits and conclude that it was a male.

How the beastie got out of its shell is discussed in great detail in the academic paper. It either lost its shell after death or it was pulled out by a predator.

In relation to the latter there is AN INTERESTING PAPER from Lyme Regis Museum concerning fatally bitten ammonites which may be relevant.

Saturday, 30 January 2021

Footprint on the Beach

Footprint on the Beach 

HERE is a nice story! A correspondent told me about it last night and it was on the radio news this morning. "A well-preserved dinosaur footprint has been discovered by a four-year-old girl on a beach."

And it was on Barry beach - not far from Bristol. It is now in Cardiff Museum and will, no doubt, be on display sometime soon. All you need to know is in the article.



Tuesday, 26 January 2021

Dinosaurs - Fundamental Matters

Dinosaurs - Fundamental Matters 

THIS ARTICLE informed me about something I didn't know, that I didn't know - an unknown unknown. Unlike mammals who have two openings "down there" dinosaurs have only one! We have one for reproduction and one for expulsion of faeces. Dinosaurs and similar have a multi purpose opening called a cloaca.

This is not commonly found in the fossil record, but a chance encounter in a Frankfurt museum with psittacosaurus - a herbivorous dinosaur of labrador size, related to triceratops - gave the opportunity to study a cloaca more closely.

And the conclusion drawn was that the animals bottom was designed, among more prosaic functions, for display. Which gives me pause for reflection.


The fossil concerned


This discovery was part of the study of psittacosaurus. There is a very interesting video HERE which goes into some detail of how to make a dinosaur.






Sunday, 17 January 2021

Where will your Electric Car really come from?

Where will your Electric Car really come from? 

A correspondent has brought this Bath Royal Literary and Scientific Institution lecture to my notice. It sounds rather interesting.

Where will your Electric Car really come from?


A study of the future availability of metals vital to emerging technologies

An on-line lecture by Professor Frances Wall of the Camborne School of Mines

 

Many countries including the UK have ambitious targets for a change from petrol and diesel vehicles to electric cars. The race is on, not only to get us to drive electric vehicles but to manufacture the cars and batteries. Other technologies such as wind turbines and a growing range of electronic devices are also needed for the sustainable society.  What is often forgotten is that the raw materials need to come from somewhere. New electric vehicles, and our other digital and clean technologies, need new metals. Not only do we need to find and mine enough of the technology metals like lithium, cobalt and rare earths, we need to make sure their production is contributing to sustainable development, not detracting from it.   

Professor Frances Wall is Professor of Applied Mineralogy, Camborne School of Mines, University of Exeter. She specialises in technology raw materials, especially rare earth elements, with interests in geology, processing, responsible sourcing and the circular economy. Frances has been leading two international consortium research projects on critical metals supply and now also leads a UK interdisciplinary Centre promoting the circular economy of technology metals. Frances was named one of the 100 Global Inspirational Women in Mining 2016 and awarded the William Smith medal of the Geological Society of London for applied and economic aspects of geology in 2019.

 

This on-line event takes place: 1st February 2021  7.30pm GMT

Book on Eventbrite £2 BRLSI members   £5 visitors:

https://www.eventbrite.co.uk/e/where-will-your-electric-car-really-come-from-tickets-135856433249

Footprints of Mass Extinction Survivor

Footprints of Mass Extinction Survivor

A correspondent has brought THIS ARTICLE to my attention. It is based on THIS PAPER which records the subject in great detail.

Tracks of the a creature were discovered in the Italian Alps, not far from the French border. And they were in rocks which have been assigned to the late Early Triassic. This is just after the Permian-Triassic mass extinction. At the time it was not far from the equator. And the temperature was rather hot.

They use photogrammetry to measure the tracks in exquisite detail.

The creature has been identified as being an archosaur - a terrestrial tetrapod but assigning a species to the trackmaker is rather difficult! But does not stop our authors! The give the tracks a name - Isochirotherium gardettensis - and then speculate that the track maker was a "a non-archosaurian archosauriform (Erythrosuchidae?)".

The main thing is that such a beast was there, so soon after the extinction event.


 

This is best seen as full screen - symbol at bottom right.

Mary Anning Statue

Mary Anning Statue 

You may know that there are plans to erect a statue of Mary Anning in Lyme Regis. A lot of money has been raised (including some of mine!) but they still need some more. If you are interested - and you should be - Go to THIS WEB PAGE and contribute. There is a very good short film to watch as well.


Denise Dutton’s preliminary sketch of how the statue will look.

Thursday, 14 January 2021

Megalodon Teeth

Megalodon Teeth 

Megalodons seem to be flavour of the month! Following on from Monday's story we have THIS ARTICLE from Bristol University's School of Earth Sciences.

Megalodon means big tooth and the beast certainly had big teeth, unlike those of other earlier members of the group. This was thought to show that the species diet had changed - the earlier members had curved, blade-like teeth, Megalodon had broad triangular ones. Therefore, it was reasoned, the earlier ones used their teeth to pierce small and fast fish. Megalodon tore off chunks of whales and seals.

But this study, using finite element analysis (described in greater detail in THIS PAPER) shows that Megalodon's teeth were weaker than the earlier ones (allowing for the change in size). This makes a lot of speculation on dietary habits redundant.

And the change in tooth morphology is due to the great size of Megalodon.



Von Mises stress distribution plots in the anterior (Ant.), lateral (Lat.), and posterior (Post.) teeth of the five analysed otodontid species, simulating (a) puncture and (b) draw scenarios with scaled force magnitude. Mesial is left, distal is right. Arrows indicate loading points. Grey areas represent von Mises stress values higher than 5 GPa and 10 MPa in each of the scenarios, respectively.

Jet Stream History

Jet Stream History 

Where was the jet stream during the Younger Dryas? And how do you map it? And how does it matter? Read all about it HERE and HERE.

The Younger Dryas was a period of cooling at the end of the last glaciation - 12.9 to 11.7 thousand years ago. It would be no surprise if the jet stream had something to do with it but how do you map the jet stream?

Answer:- look at the glaciers of the period; identify the equilibrium line altitude (ELA) where ablation (mass lost) equals accumulation (mass gain); from that draw a map of precipitation across Europe 12,000 years ago. Simple! The sources tell you how to do it. 

Western Europe and the eastern Mediterranean were wetter than now. The bit in between was drier. And from this you can map the jet stream. 

Current computer models of the climate do not show this. To have confidence in predictions of future climate we need models which model the past with some degree of accuracy. Work such as described above helps in this.




Equilibrium Line Altitude  elevation surface for the Younger Dryas.

The ELA surface should be viewed as “theoretical” (ELAthl) because glaciers can only form where the topography is higher than the ELAthl surface. For example, there are no glaciers in SE England or the low countries. Black dots show the location of palaeoglacier reconstruction sites. The FIS and the West Highlands icefield are shown, but the ice mass in the Alps is not shown due to incomplete knowledge of its geometry at this time.

Monday, 11 January 2021

Pregnant Megaladons - Avoid!

Pregnant Megalodons - Avoid!

If you can't find a scary dinosaur story a scary Megalodon story is almost as good! 

The source is THIS ARTICLE, referencing this ACADEMIC ARTICLE

Megalodons are extinct (thank goodness!) predatory sharks which grew up to 14 metres and died out about 3.6 million years ago. Being sharks, fossils are hard to come by as their skeleton is largely cartilaginous. But some parts can be mineralised and therefore preserved. Teeth (17cm.!) get a lot of attention but it is the spine which is the focus of the paper.

The vertebrae come from a specimen found in Belgium. X-ray scanning of the vertebrae revealed the internal structure and showed it to have growth rings, presumed to be annual. If so the beast died when it was 46 years old and was 9.21 metres long. The academic article details how this was worked out.

But what is fascinating is that it was 2 metres long at birth! And how did it get to be so big - by eating its siblings in the womb! It could not have been an easy pregnancy for the mother! (I may be projecting human values onto a shark in the last sentence. It was probably entirely normal for Megalodon mummies.)


Examples of examined vertebrae of Otodus megalodon (IRSNB P 9893). (a) One of the largest vertebrae (‘centrum #1ʹ) in IRSNB P 9893 (scale bar = 10 cm; photograph courtesy of IRSNB). (b) Computed tomographic image showing sagittal cross-sectional view of vertebra depicted in (a) (scale bar = 5 cm). (c) Computed tomographic image of sagittal cross-sectional view the largest vertebrae (‘centrum #4ʹ) in IRSNB P 9893 showing incremental grown bands presumably formed annually (* = centre of vertebra; scale bar = 1 cm)

Wednesday, 6 January 2021

DOWN TO EARTH EXTRA - JANUARY 2021

 


DOWN TO EARTH EXTRA - JANUARY 2021

The latest edition of Down to Earth Extra is HERE.

And you can read it below.