"Hidden ‘star’ sand dune mystery solved by ancient find
These are seen forming today around the earth, and even on other bodies in the solar system.
But strangely, geologists can’t find any in Deep Time.
Q: Why is that?
Geologists at Aberystwyth went to Morocco to look for clues and took their divination tool with them.
They observed an existing star dune, not any in the geologic record.
"The research reveals the oldest parts of the base of the Moroccan dune are 13,000 years old. However, the discovery that it had formed rapidly in the last thousand years surprised scientists who had thought larger dunes were far older.
Believed to be the tallest dunes on Earth – with one in the Badain Jaran Desert in China reaching 300 metres high – star dunes are also found elsewhere in the solar system, on Mars and on Saturn’s moon Titan.
Despite being common today, star dunes have almost never been found in the geological record. Their absence has bemused scientists as past deserts are a common part of the history of Earth, preserved in rocks deep underground."
They observed an existing star dune, not any in the geologic record.
Q: How does that solve the mystery?
“This research is really the case of the missing sand dune – it had been a mystery why we could not see them in the geological record. It’s only because of new technology that we can now start to uncover their secrets. These findings will probably surprise a lot of people as we can see how quickly this enormous dune formed, and that it is moving across the desert at about 50 cm a year. These fantastic star dunes are one of the natural wonders of the world.”
Just like in Darwinian biology, Stuff Happens at different rates at different times. The model required some radical time adjustments. No slow and gradual dune formation here! It’s more like punctuated equilibria in evolutionary biology:
"The scientists’ breakthrough research suggests the star dune formed at around the same time as the Younger Dryas event, an abrupt cooling period in Earth’s history. It also reveals that the dune stopped growing for a period of 8,000 years.
Pottery found at the site also suggests wetter conditions, perhaps an enlarged monsoon, that stabilised the dune before the onset of a great drought.
The study used luminescence dating techniques developed at Aberystwyth University to discover the last time minerals in the sand were exposed to sunlight to determine their age."
They are proud of their homegrown divination method, but have to
They never got back to why star dunes are not found in the geological record. Does their paper in Science Advances help? No; they just explain it away as something that’s hard to identify, but they have some futureware to sell.
"Individual sedimentary structures in star dunes are similar to those in linear or barchanoid dunes, likely leading to misidentification in the rock record. However, the suite of features described in this paper will permit identification of star dunes in future studies of the rock record. Optically stimulated luminescence (OSL) dating shows that accumulation of the Erg Chebbi star dune post-dates the end of the African Humid Period (AHP). At the base of the dune, there is an ~ 8000-year hiatus in the record. Since then, the dune has grown rapidly to create a 100 m high dune within the past 1000 years and is migrating towards the west. Changes in the cross-strata support the idea that star dune construction was accompanied by a change in the wind directions."
Q: Is this plausible?
---Their deep-time narrative goes like this:
--A long time ago, a big erg (sand field) with a star dune forms in Morocco.
--Then nothing happens for 8,000 years.
--Then the wind shifts.
--A world record star dune piles up within centuries, and it’s moving. Yes, stuff happens in strange ways.
Q: Are you bemused like these geologists? (bemused: bewildered, confused, lost in thought, preoccupied).
Q: Are you bemused like these geologists? (bemused: bewildered, confused, lost in thought, preoccupied).
No need to be.
Read Genesis 1-12 to see what happened."
CEH