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!

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.

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".

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.

Down to Earth Extra - February 2021

The latest edition of Down to Earth Extra is HERE.

And you can read it below.

 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.