Down to Earth Extra November 2025

The November 2025 edition of Down to Earth Extra has been published. You can download it HERE or you can read it below.

Jurassic Lives Uncovered

A little while ago I was complaining about a lack of local geological stories. Then two come along at once! You have probably read all about them yourselves but just in case, here is what I have found out.

First of all - Xiphodracon goldencapensis - is an 185 million year old icthyosaur found in 2001 in the cliffs between Charmouth and Seatown. I read about it first in a BBC ARTICLE and, later, tracked down the ACADEMIC PAPER which describes the beastie in great detail. The lead author of this paper, Dean Lomax, is based at Bristol and Manchester Universities.

The holotype and only known specimen of the hauffiopterygian leptonectid, Xiphodracon goldencapensis (ROM VP52596) from Golden Cap, between Charmouth and Seatown, Dorset, UK. The skeleton is exposed in ventrolateral view. The skull has been fully prepared free of matrix whereas most of the skeleton is still in matrix. The left (upper) forefin has been prepared so that it is three-dimensionally preserved and projects upwards. Scale bar represents 20 cm.

The animal has been identified as a new species and dated as being from the early Pliensbachian. This is a time from which few icthyosaur fossils have been collected and this makes the find of some importance.

And secondly - a dinosaur trackway found. The BBC has produced a YOUTUBE VIDEO about the discovery of a very long sauropod trackway in an Oxfordshire limestone quarry. One suspects that a documentary is on its way.

The trackway is over 220m long and is thought to have been made 166 million years ago. The dinosaurs were land animals but they were walking in shallow sea water - there are marine fossils next to the footprints. 

Anne Bronte's Rocks

 Anne Bronte's Rocks

A correspondent, in reply to my remark that it was becoming difficult to find things suitable for this blog, sent me THIS LINK to the journal "Bronte Studies". This journal does not usually find its way to the top of my reading list but it takes us back to a time when being educated meant being interested in everything!

If you go to the Bronte Parsonage Museum you will see Anne Bronte's collection of stones.

 Anne Bronte’s collection of stones, as displayed at the Bronte Parsonage Museum. Courtesy of the Bronte Society.

The collection has been studied and found to be largely carnelians - a form of the silica mineral chalcedony. There is also a piece of flowstone and a couple of agates. The stones could not all have come from one site and they seem to have been deliberately chosen.

The article suggests that Scarborough is the most likely place where Anne collected her rocks. Her work as a governess took her to the place. She may have collected them herself or purchased them from a lapidary, of which there were several within the town. Some of the carnelians are of high quality and suggest that Anne knew what she was doing while making her collection. She certainly valued her collection enough to take it back to Haworth.

(You have probably noticed the plethora of links in this post. This is a new feature of Blogger, the app which I use to write this blog. I suspect that I will turn it off in future posts.)

 Air Balloon Geology

Recently a subscriber to this blog asked "I wonder if you know of any geological treatise on the A417 "Missing Link" at the Air Balloon pub site? ..... They plan to keep the strata exposed for all to see when driving past, like has been done on the Cirencester dual carrageway."

Well, the short answer is that I do not know what is happening there. If you do, send me the details HERE and I will pass them on. 

But the request sent me on a mission to discover what the geology is at the Air Balloon Pub. My knowledge of the place is being stuck in a traffic jam, waiting to get on to the M4 at Gloucester. And I discovered the latest addition to the BGS web site - the GeoIndex Beta.

With a little persistence I managed to produce the following map.

The original map can be found HERE.

If you click, on the original map, on a formation you get a pop-up similar to the following:-

The link takes you to THIS PAGE which tells you a lot about the Birdlip Limestone. The parent of this page IS THIS - the Lexicon of named rock units of the BGS.

I used this to name several of the formations on my Air Balloon map.

To search the Lexicon use the Computer Code given in the pop-up, or the Preferred Map Code. (This the code in the last line of the rock names I have put on my Air Balloon map.)

So now I know a great deal more about the Air Balloon Pub area and know how to access a vast amount of Geological Knowledge, but I still cannot answer the question which started this search!

 Dead Sea Models Salt Deposition

A correspondent sent me THIS LINK. The article is based on THIS ACADEMIC PAPER. The Dead Sea is, at the moment, the only water body sufficiently deep enough and salty enough to model the conditions which produced the vast salt deposits which are found in many places and times in the geological record.

The academic paper, in particular, examines, in great detail, all the things which determine the salt deposition. These include temperature, which varies with the seasons, salt concentration which varies with depth, temperature and the season, evaporation which depends on temperature and wind, wind which affects mixing, sizes of the deposited halite crystals and beach deposits.

Reading the reports makes me realise that it is very complicated! And that I am ill equipped to explain it all to you! So read the papers, and hope that you can begin to understand what is going on. 

 Is the Core Separate from the Mantle - Maybe Not

A correspondent sent me THIS LINK which looks at new evidence suggesting that material from the core is getting into the mantle and, eventually, to the Earths surface.

We have long been taught that the lighter mantle floats above the denser metallic core and that there cannot be movement between the two (except for earthquake waves).

But work on helium isotopes casts doubt about the separation. Helium-3 was formed just after the Big Bang and was confined to deep in the Earth, some believed it was confined to the core. Helium-4 is formed from the decay of uranium and thorium and is confined the mantle and the Earths surface. But then Helium-3 was found in volcanic lavas from mid-ocean ridges.

Ruthenium is an element with an affinity for iron and thus is concentrated in the iron-rich core. This applies particularly to Ruthenium-100. Other ruthenium isotopes came to Earth later via meteorites but Ruthenium-100 should be confined to the core. But it is now found at the surface.

So how is the core stuff getting into the mantle? Debate rages with a lot of attention being paid to two huge "blobs" - one under the Pacific and the other under Africa. These are believed to be hot but dense and supplying plumes leading to the surface. Are they "mining" the core or are they a bridge from the core to the surface.

Expect to hear more about this in the future.

 Down to Earth Extra August 2025

The August 2025 edition of Down to Earth Extra has been published. You can download it HERE or you can read it below.