Down to Earth Extra - October 2021

  Down to Earth Extra - October 2021 
 

The latest edition of Down to Earth Extra is HERE.

And you can read it below.

 

Apocalypse Then 

I came across THIS ARTICLE today and thought it very interesting if not particularly geological. It is a popularisation of THIS PAPER in Nature.

It concerns the total destruction of Tall el-Hammam, a Middle Bronze Age city north east of the Dead Sea, in Jordan. This occurred about 3,600 years ago and it is speculated that it may have inspired the Old Testament story of the annihilation of Sodom. There is a Lot of evidence. (Sorry!)

The site has been excavated for 15 years and is continuing. Objects found which are of interest include, pottery sherds with glassy surfaces, melted mudbrick fragments, melted building plaster. One begins to think of an extremely high temperature event.

Also the buildings did not just fall down - they were levelled. Walls were sheared off. Most of the mud bricks were pulverised and blown off the site to the north east.

Could this be signs of warfare - No. There is a complete lack of arrowheads, sling stones and spear points at the destruction layer.

The researchers did not find nanodiamonds (often found at sites of cosmic impact) but they did find diamonoid particles - the smallest unit found in the diamond crystal lattice. Shocked quartz was also found.

There is much more evidence described in the articles and they all lead to the conclusion that there was a cosmic airburst a bit bigger than the Tunguska event in Siberia in 1908.

Both articles are well worth reading. And both are free!

The comments on the first article are enlightening and entertaining. The suggestion that the Sumerians had atomic bombs but not wheels is dismissed.

Catastrophic leveling of the palace at TeH. (a) Artist’s evidence-based reconstruction of the 4-to-5-story palace that was ~ 52 m long and 27 m wide before its destruction. (b) Artist’s evidence-based reconstruction of palace site on upper tall, along with modern excavation. “MB II” marks the top of 1650-BCE Middle Bronze rubble. Note that the field around the excavation is essentially flat, unlike the view in panel ‘a’. Originally, parts of the 4-story palace were ~ 12 + m tall, but afterward, only a few courses of mudbricks remain on stone foundations, labeled as “wall remnants”. Part of the foundation of the massive wall around the palace is at the bottom. Debris from between sheared walls has been removed by excavation. A comparison of panel ‘a’ to panel ‘b’ shows that millions of mudbricks from the upper parts of the palace and other buildings are missing.

Meet the Magma Tree 

Two correspondents have brought THIS ARTICLE to my attention - many thanks and keep them coming! The article is based on AN ARTICLE (£) in Nature Geoscience. (The pound sign indicates that you need to pay to read it.)

The article describes research which has been going on for decades. Using seismometers to determine the inner structure of the earth is now developing to describe the plumes which bring volcanism to the unexpected parts of the globe. And now researchers think they have found "a titanic mantle plume "tree"" which rises from core mantle boundary.

One of the branches of the tree hits the surface at the Indian Ocean island of La Réunion. It has an extremely active volcano but is more than 1,000km from the nearest plate boundary. It is the current end of a track which leads to the Deccan Traps of India which produced 10⁶km³ of basalt around 65 million years ago.

Much effort has been expended in mapping the Réunion plume and the other plumes of the magma tree and the articles describe how they look as they do. And also does some predictions into the future - Africa seems to have a fiery future!

There is far too much to describe here - read the article!

The caldera of the Piton de la Fournaise on Réunion.
Henner Damke/Shutterstock

Underwater Glacial Geomorphology 

A correspondent spotted THIS on the BBC website and passed it on to me.

It concerns sub-glacial landforms which were made under ancient ice sheets. These were where the North Sea is now and have only recently been discovered using seismic survey techniques. Deep seismic techniques are used to find possible oil bearing structures, these shallow ones were originally developed to find suitable foundations for oil industry infrastructure,

The structures may give us a picture of what is happening beneath Greenland's ice cap as it melts under today's conditions of global warming.

How the Moon Made Life on Earth Possible

A  correspondent brought two links to my notice. THE FIRST is the scientific paper on which THE SECOND (a YouTube Video) is based. If you are anything like me you will find the video much more approachable.

The thesis is multi staged. 

• The moon slows down the rotation of the Earth.
• Oxygen producing cyanobacteria rise to the sea surface during daylight.
• Anaerobic bacteria rise to the sea surface at night.
• Cyanobacteria rise slowly.
• When day length is short cyanobacteria are not in daylight for long.
• Longer days mean more oxygen produced.
• Oxygen in the atmosphere allows multicellular life to develop.

You can read all about it in the Nature paper, or you can watch the video. Also in the video you have the chance to buy a T shirt!!!

You can read about the sinkholes which feature in the previous links HERE.

A term used in both paper and video is "diel". It is one I had not come across before. It is usually phrased as diel vertical migration, and Wikipedia defines it as:- 

Diel vertical migration (DVM), also known as diurnal vertical migration, is a pattern of movement used by some organisms, such as copepods, living in the ocean and in lakes. The migration occurs when organisms move up to the uppermost layer of the sea at night and return to the bottom of the daylight zone of the oceans or to the dense, bottom layer of lakes during the day. The word diel comes from the Latin dies day, and means a 24-hour period. In terms of biomass, it is the greatest migration in the world. It is not restricted to any one taxon as examples are known from crustaceans (copepods), molluscs (squid), and ray-finned fishes (trout). Various stimuli are responsible for this phenomenon, the most prominent being response to changes in light intensity, though evidence suggests that biological clocks are an underlying stimulus as well. The phenomenon may arise for a number of reasons, though it is most typically to access food and avoid predators. While this mass migration is generally nocturnal, with the animals ascending from the depths at nightfall and descending at sunrise, the timing can be altered in response to the different cues and stimuli that trigger it. Some unusual events impact vertical migration: DVM is absent during the midnight sun in Arctic regions and vertical migration can occur suddenly during a solar eclipse.

Dave Green's Programme for 2021 - 22 

Dave Green has produced a programme for the next year which is bursting with geological goodness!. I have put down my name for the trip to the Eastern Pyrenees next February already!

You can download the programme HERE.

Or read it below. 

Down to Earth Extra - September 2021

  Down to Earth Extra - September 2021 
 

The latest edition of Down to Earth Extra is HERE.

And you can read it below.