Saturday 28 January 2023

Three Film Series on the Geology of Ireland

Three Film Series on the Geology of Ireland 

A correspondent alerted me to the existence of this series. You can, if extremely persistent, find them on iPlayer. The easy way is to go to the programmes WEBSITE from which you can get the iPlayer link.

So far I have watched the first episode and it is reasonably good. Not all the contributors are experienced media performers but what they say is good stuff. And the scenery is superb.

Thursday 26 January 2023

Down to Earth Extra February 2023

Down to Earth Extra February 2023

The February 2023 edition of Down to Earth Extra has been published. You can dowload it from HERE or you can read it below.

Saturday 21 January 2023

How did Pterosaurs Learn to Fly?

How did Pterosaurs Learn to Fly? 

THIS ARTICLE discusses new evidence about the early days of reptile flight - and comes to no great conclusion.

Pterosaurs are the first reptiles to fly. They are not dinosaurs, although both are reptiles. 

The article discusses work done on fossils of Scleromochlus, now thought to be related to lagerpetids, which are a sister group of the pterosaurs. There is an article in NATURE (but paywalled) and HERE. The conclusion is that Scleromochlus is a pterosaur ancestor but the evidence for suitability for flight is absent. The conclusion reached is that the "first flying reptiles evolved from tiny, likely facultatively bipedal, cursorial ancestors".

The interest of the article is the amount of data that is now being found using CT scans. The fossils were found near Lossiemouth in Scotland in Late Triassic sandstone, more than 100 years ago. They have been much studied (by, among others, Mike Benton) but the conclusions reached were even less definitive.

Pterosaurs are not dinosaurs. Warpaint/Shutterstock

Thursday 19 January 2023

Earth Heritage 58 out now

Earth Heritage 58 out now 

You can download your copy of Earth Heritage 58 HERE. Or you can read it below.

Wednesday 11 January 2023

Barometric oscillations in UK caused by the Hunga-Tonga volcano

 Barometric oscillations in UK caused by the Hunga-Tonga volcano

I am a retired meteorological Office observer and I recorded traces of the atmospheric pressure surges caused by this eruption on my barograph which I have at home in Royal Wootton Bassett.

The barogram trace recorded on my instrument in Royal Wootton Bassett with time divisions at 2-hourly intervals

I thought they might be of interest to the readers of this blog. 

The Hunga-Tonga volcano eruption, at 0626Z on 15th Jan 2022 sent out a shock-wave which travelled around the globe.  Its audio-frequency, in Herz, fell with increasing distance in a similar way to thunder.  The shock-wave sound just went on getting lower in pitch as it raced away till it was far below the 20 Hz threshold of human hearing.  

By the time it got to the UK, 13 hours later, it was around 0.002 Hz.  In other words 10-15 minutes per single Herz.  It registered on barographs in the UK as a spike of 2-3 hPa amplitude travelling at the speed of sound, i.e. 20 Km per minute.  A second pressure signal arrived the next morning.

 Pressure readings at Southport.
Finer scale pressure graph of the 1900 peak and following dip, and dip around 0200Z.  x-axis =hourly time lines, y-axis pressure in 0.2 hPa steps.

Pressure readings at Stockport
Another paper barogram but with 3-hourly time divisions, midnight in bold. All 3 graphs show how widespread and similar the basic 2 events were.

After studying the timings of both at several weather stations' barograph records, it was apparent that there was just one shock-wave front, arriving via short- and long-paths. The first pulse came from the north, but the second one went the long path round the globe to arrive from the south.  

Arrival times of the shock waves

Sonic pressure surges like these occurred from the 1893 Krakatau eruption and also the Chelyabinsk meteorite explosion.

(Note that barometric oscillations are more usually caused by atmospheric gravity-waves travelling at speeds of 20-40 knots. Gravity waves are anomalies in the density and/or instability of the air causing the pressure to oscillate as the wave passes over, similar to water waves).

Richard Gosnell, Royal Wootton Bassett, Jan 2023

⃰(Z, zulu, equals GMT/UTC.  Each global hour-timezone is sequentially lettered, e.g. A for Central European time, B for the next zone eastwards, etc ending up at Z for GMT=UTC.  I recall that “I” and “O” are omitted to avoid confusion with numerical digits and neatly providing 24 letters for 24 hours)

⃰ (Hectopascals, being the S.I. unit for pressure, identical to Millibars)

Saturday 7 January 2023

Did Life on Earth Come from Asteroids?

Did Life on Earth Come from Asteroids? 

A correspondent brought THIS ARTICLE to my attention. It concerns the discovery of amino acids in the asteroid 162173 Ryugu. 5 grams of this asteroid were brought to Earth by the Hayabusa2 space mission. 

Amino acids are essential for life. They are not difficult to make - and the Ryugu discovery suggests that they could be made by gamma rays in asteroids! 

The carbonaceous chondrite Murchison meteorite which landed in Australia in 1969 had amino acids and their concentration in the meteorite could have been raised from zero, by gamma rays, in anything from 1,000 up to 100,000 years.

Part of the Murchison meteorite, photographed in the Maine Mineral and Gem Museum, Bethel, Maine by me on 5th October 2022.

The article notes that amino acids in the early Earth could have come from several, if not many, sources. Asteroids have been added to the list.

Making Sense of the End-Ordovician Mass Extinction

Making Sense of the End-Ordovician Mass Extinction 

THIS ARTICLE discusses the End-Ordovician mass extinction, the second-most severe in the Earth's history. The difficulty with this extinction is that all the usual suspects are absent - no meteor craters, no vast pile of lava. 

I addition there was an accompanying diversification in life. Many of the life forms from the Cambrian were replaced. And there was a lot of glaciation about.

How can it be explained? The article gives one attempt. It uses the position of the Earth's magnetic pole during the period between 460 and 435 Ma. And it seems to have whizzed about rather quickly. The researchers have the hypothesis that the lithosphere rotated 50° relative to the Earth's axis. This requires a speed of 55cm per year!

Palaeogeographic reconstructions charting true polar wander and the synchronised movement of all continental masses between 460 and 440 Ma. Note the changes in the trajectories of lines of latitude on the Mollweide projections. The grey band either side of the palaeo-Equator marks intense chemical weathering in the humid tropics. Credit Jing et al. Fig 5.

The article discusses the affect this would have. Habitats zooming through different climate zones would kill off many species. Equally it would give the opportunity for new species to develop. (Sounds a bit like Brexit!).

Read the article and the academic article it is based on. You can get the pdf of the Nature article HERE.