How Old are Sponges? 

A correspondent sent me the link for THIS ARTICLE - many thanks. It is based on THIS ARTICLE in Nature. 

The researcher, working on 890 million year old reef rocks, found structure in some of her thin sections which looked rather like those found in more modern rocks. She did this 10 years ago. In the intervening period there have been many publications which have identified similar structures as being sponges.

But her rocks were more than 400 million years older than the oldest confirmed sponge. And the oxygen content of sea and atmosphere was rather different. But she argues that the cyanobacteria, that made the reefs she was working on, were close enough to her sponges to provide enough oxygen.

So, perhaps sponges are the oldest animals and were around for a lot longer than we thought.

ABOVE: A low-magnification view of the connected network of tunnels that form a putative sponge protein skeleton fossil found in an 890-million-year-old rock. The field of view is about 9 millimeters.

EC TURNER

 

The Earth's Inner Core 

I came across THIS ARTICLE and now know more about the inner core than I did before - and some of it is very surprising!

The inner core is solid but is very hot and under great pressure. Previously it was even hotter and was liquid. When did the temperature drop low enough to allow solid iron to appear? Between 500 and 1,500 million years ago. People discovered its existence in 1936.

Its radius increases by 1mm per year. This implies 8,000 tonnes of iron solidify every second! Eventually all the core will solidify and the Earth will not have a magnetic field.

The inner core is lop-sided. The eastern part, under Indonesia, is growing faster than the western part, under Brazil. But, thankfully, gravitational forces sort things out and the core remains spherical.

The article tells us how all this is surmised - none of this can be found first hand! Read the page - there is lots of good stuff therein.

Seismic waves have suggested Earth’s solid iron core is asymmetrical. Sanne Cottaar, Author provided

A "Jurassic Pompeii" - Somewhere in the Cotswolds 

Many of you must have seen THIS WEB PAGE from the BBC. A correspondent brought it to my attention - Thank You!

At first glance the article looks like a very superficial piece of work, but it isn't. There is a lot of information about the geology, the palaeontology, the sedimentology and the excitement of scientific discovery. Read all the page - it goes on for a long way - look at the photos, play the videos. It is a good example of making geology interesting.

At the moment the location is secret. No doubt, some of you can work out where it is. I look forward to seeing the specimens in the Natural History Museum.

Frozen in time: Fossilised seafloor animals from the Jurassic, all piled on top of each other

Seismology of Mars 

A few years a go WEGA had a lecture from a Bristol University lecturer on this subject. He was somewhat limited as the only seismometer on Mars was ON a lander which had a very effective suspension. He thought that you would need an earthquake marsquake above 8 on the Richter scale to be recorded! So a lot of his talk was about the next seismometer on Mars. 

And that seismometer is the subject of THIS ARTICLE by two researchers at Bristol. 

The seismometer has detected hundreds of quakes and the conclusion is that Mars has a much larger core than previously thought. Because it is larger it must have a larger proportion of lighter elements than Earths core. And such a composition would not have an inner solid core - and hence no magnetic field.

The crust of Mars has been estimated from the quakes as 24 to 72km thick and the lithosphere 400 to 600km.

Shear waves travel from a marsquake and reflect off the iron-nickel core. Chris Bickel/Science

Even More Iceland Volcano Videos 

John Nicklin of the Teme Valley Geological Society has, among other things, sent me A LINK to three very good drone videos. Three different styles but all good. They are all on YouTube so I can embed them below.

Stonechat July 2021 

I have been sent a link to "Stonechat" the magazine of the Horsham Geological Field Club. It is well worth reading, especially the article on Rock Bands! You can get it HERE, or read it below.

Fossils Are Found in the Most Unexpected Places! 

A correspondent brought THIS ARTICLE to my notice - Thank You! It discusses THIS ACADEMIC PAPER.

The Barberton Greenstone Belt in South Africa is very old - 3.42 billion years old. The rock discussed is interpreted as a subseafloor hydrothermal vein.

3.42-billion-year-old chert veins (dark gray) in rocks at the Barberton Greenstone Belt in South Africa

AXEL HOFMANN

The researchers found (using sophisticated microscopes and other instruments) that they were looking at filamentous cellular colonies. Because they were in rocks which originated deep below the sea floor, they obtained their energy from chemical processes and probably generated methane.

Down to Earth Extra - July 2021  

The latest edition of Down to Earth Extra is HERE.

And you can read it below.