Venusian Tectonics 

We know remarkably little about Venus - the second rock from the sun - but THIS ARTICLE summarizes what we do know and goes on to talk about the planets tectonics.

Radar images give us our best picture of the planets surface. There is little erosion but also very few impact craters. This has led to speculation that the planet gets a new "carpet" every few hundred million years. If we presume Venus's composition is similar to that of the Earth, there must be a build up of heat in the planets interior. The Earth gets rid of it by means of plate tectonics, but Venus does not - the heat is got rid of by means of a vast volcanic episode which resurfaces the planet.

Polygonal blocks or ‘campuses’ on the lowland surface of Venus. Note the zones of ridges that roughly parallel ‘campus’ margins. Credit: Paul K. Byrne, North Carolina

 State University and Sean C. Solomon, Lamont-Doherty Earth Observatory

The article, while not contradicting the mega volcanic story, suggests another means of Venus losing heat. This is the jostling of what they call campuses on the surface of the planet. There is no lithosphere formation or destruction but implies mantle convection.

Hopefully the lack of evidence will be cured by the recently announced missions to Venus.

Huge Diamond Discovered - But Not By Me! 

A correspondent brought this to my attention. It is from The Mineralogical Record but I could not find an online source, so I have copied some of what he sent me.

The Debswana mining company in Botswana recently announced the discovery of a huge diamond that they believe ranks as the third-largest gem-quality diamond crystal ever found—the two larger ones being the Cullinan (3,106 carats, found in 1905) and the Lesedi La Rona diamond, 2,109 carats, found in 2015). The new, as-yet unnamed diamond weighs 1,098 carats (7¾ ounces) and measures 7.3 cm (2.9 inches) × 2.7 × 5.2 cm. If you had this crystal in your collection and wanted to compete with it at the Tucson Show, it might be a bit too large for the “miniature” category (maximum 2 inches), so you would have to enter it in the “small cabinet” category!

 

The crystal was found at the Jwaneng mine, located about 75 miles from the capitol city of Gaborone and operated jointly by the Botswana Government and the De Beers Group. Officially opened in 1982, the mine typically yields between 12.5 million and 15 million carats of diamonds a year. This month's find is the largest gem unearthed by the company since diamonds were first discovered in Botswana in 1967. Whether the new diamond will be sold through De Beers channels or through the state-owned Okavango Diamond Company has yet to be decided, so you still have a chance to acquire it for your collection. But you’ll need deep pockets; the Lesedi La Rona diamond sold for $15 million.

The diamond is sub-rounded. Presumably on its journey up the kimberlite pipe the corners got knocked off. 

I once found the diamond from my wife's ring on the kitchen floor, but it was a bit smaller than this one.

Coal's Future - Hydrogen Storage? 

I came across THIS ARTICLE and found it interesting for a couple of reasons. 

Recent research shows that coal can store gases and the amount absorbed increases with pressure - 600kg per ton of fractured coal. The suggestion is that old coal mines could act as batteries storing hydrogen produced from sources such as wind power. 

I suspect the engineering required for this to happen is some distance in the future, but it is a nice thought.

The other reason this article was of interest was the graph showing the historical contribution of various energy sources. The implications for the future are rather frightening.

Growth in energy supply from different sources since 1800 CE (Credit: ourworldindata.org)

Articles of Interest 

I have been quite busy this week and not able to give as much time to the blog as I would like. But my correspondents send me stuff which is worth passing on. Below are the links to web pages sent to me. Normally I like to write something about them but don't have the time this week. - Sorry!

• https://www.scientificamerican.com/article/mushroom-evolution-breaks-down-lignin-slows-coal-formation/

• https://news.umich.edu/egyptian-fossil-surprise-fishes-thrived-in-tropics-in-ancient-warm-period-despite-high-ocean-temperatures/

• https://www.quantamagazine.org/seismic-data-helps-scientists-forecast-volcanic-explosions-20210601/

• https://www.nationalgeographic.com/science/article/an-earthquake-lasted-32-years-and-scientists-want-to-know-how

• https://www.sciencemag.org/news/2021/06/rise-and-fall-world-s-largest-lake?utm_source=Nature+Briefing&utm_campaign=6b35e184ca-briefing-dy-20210607&utm_medium=email&utm_term=0_c9dfd39373-6b35e184ca-45855494

All of these are worth looking at. My apologies for not dressing them up a little.

How Geology Affects Politics 

I came across THIS on Twitter.

In the election results, blue is Democrat, red is Republican. (This counterintuitive for us Brits.)

The fertile soil was good for cotton, - and hence, lots of slaves.

Congo Canyon Turbidity Current 

I suspect many of you have seen this on the BBC website, but HERE it is for the rest of us. The turbidity current current occurred on the 14th January 2020 and swept 1,100km into the Atlantic breaking a couple of submarine cables.

The event occurred a couple of weeks after a 50 year flood on the Congo river. This dumped a vast amount of material at the canyon head. There is speculation about why there was a pause between the flood and the turbidity current. The avalanche started at low tide, when the pore pressure inside the sediment is at its highest.

The Congo Canyon has many instruments along its length so the speed of the current could be measured.

The Scablands 

A correspondent brought THIS VIDEO to my attention and it interested me for two reasons. The first is that it is about the Ice Age Floods of the Scablands in Central Washington which I visited on a WEGA excursion led by Doug Robinson in May 2016. We stayed in Ellensburg which is the home of Central Washington University with which the speaker is affiliated.

The second is that it is a journey back in time. He speaks in front of a blackboard with chalk! It brings me back to the days of my youth.

I haven't watched all of the video yet but the guy seems to know what he is talking about. I'm looking forward to seeing the rest.

Geologic Map of the World - Online 

I came across THIS WEB PAGE and thought you might find it interesting. You can zoom in and a lot of the sea bed has also been mapped

The UK

And you can get fairly detailed views.

Bristol

There is a vast store of knowledge incorporated and sometimes you can get references to look up when you click on a spot. Happy exploring!

Down to Earth Extra - June 2021 

The latest edition of Down to Earth Extra is HERE.

And you can read it below.