UKC

We always knew Torridon was primordial...

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 wiwwim 29 Apr 2021
In reply to eaf4:

that's amazing.  I always knew I was Scottish

 Lankyman 29 Apr 2021
In reply to eaf4:

'the fossil is a collection of interlinking cells with attached strands of what looks like ginger hair ....'

 Doug 29 Apr 2021
In reply to eaf4:

for anyone interested in the original article

https://www.cell.com/current-biology/fulltext/S0960-9822(21)00424-3

(open access)

 DaveHK 29 Apr 2021
In reply to wiwwim:

> that's amazing.  I always knew I was Scottish

This could have powerful implications for our rugby team. How far back are you allowed to go in ancestry?

 wercat 29 Apr 2021
In reply to eaf4:

that is utterly fantastic!  People who knew about geology while I was up there in the 80s often quoted those rocks as predating life (so far as anyone knew) but I always had a prickling at the back of my neck out in the wilds or on Cioch Nose etc looking at that ancient rock and just wondering what might be SlyHiddentherein.

for this so old to be found and to be of this nature is wonderful!

 wercat 29 Apr 2021
In reply to wiwwim:

sorry to tell you it was elsewhere then ....

In reply to wercat:

The Torridonian has never been thought to predate life, as far as I'm aware - the oldest parts of it are "only" about 1.2 billion years old, and single-celled microfossils have been being found in it for a long time.

The Lewisian, that underlies it below an erosional unconformity, is a different matter - the older parts of it are thought to be over 3 billion years old, with some evidence for parts having an even older source.

Even then, there is evidence of life preserved in some ancient (3.7-ish billion years) rocks in Greenland - although it's disputed; there's clearer evidence in some Australian rocks dating from a couple of hundred million years later than those.

Edit - life seems to be pretty old, perhaps appearing quite soon after the Earth was able to support it.

Post edited at 12:31
 wercat 29 Apr 2021
In reply to skog:

That is interesting - perhaps the people saying so back then were not as well informed as they thought they were!  Or were not as precise as what you say.

Interesting nevertheless and I'm glad to be better informed.

 elsewhere 29 Apr 2021
In reply to skog:

I just think it's amazing that fossils have survived so long when most rock from that era must have been through some or all of being ground to a powder by a glacier, washed down into the sea, deposited as sedimentary rock, subsumed into the earth's crust and then thrown up as lava by a volcano.

It might have even happened every 100 million years or whatever the average age of the earth's surface layers is. Anybody know how many times a bit the earth's surface is likely to have been recycled into something else (geologically) and somewhere else?

Post edited at 12:51
In reply to elsewhere:

> It might have even happened every 100 million years or whatever the average age of the earth's surface layers is. Anybody know how many times a bit the earth's surface is likely to have been recycled into something else (geologically) and somewhere else?

I couldn't give you an average age of the crust and upper mantle, but the thing is it's quite different in different places, for different suites of rock. The Torridonian was mostly deposited on-land, in a desert-like landscape because there weren't land plants at the time, but not necessarily dry; many deposits are from rivers or lake. The area gradually sank down (due to plate movements), and other sediments were deposited on top of it (including plenty of marine ones, which can be seen widely further North and include the 'pipe rock' and the Durness Limestone amongst others. But the Torridonian deposits were then protected from the surface by the rocks and sediments above them, and were ultimately brought back up by a combination of continents colliding and thrusting huge sheets up and across, and by huge amounts of igneous rocks being injected and accreted underneath Scotland during the Tertiary, lifting everything else up.

More generally, the continents have been building up for billions of years as the less dense rocks have essentially been left floating on top - so parts of the continental crusts are very old indeed. Oceanic crust is more of a temporary thing - forming as plates move apart, and being consumed again as they move together; it's more dense, so sinks away back below and gets recycled (although some bits do get scraped off and incorporated into island and mountain chains).

Post edited at 13:14
 Doug 29 Apr 2021
In reply to skog:

By coincidence, I'm re-reading Richard Fortey's 'Life: A Natural History of the First Four Billion Years of Life on Earth' at the moment. As its some 20 years old I guess some of the detail is out of date but its a very readable account of the evolution of life & of the Earth's geological history.

 elsewhere 29 Apr 2021
In reply to skog:

Cheers! We are the scum living on the scum that floats on top!

In reply to elsewhere:

> We are the scum living on the scum that floats on top!

Ha, yeah, I suppose we are!

In reply to Doug:

I haven't read that, it looks great.

I'm particularly interested in the way that life seems to probably have popped up not too long after the Earth's surface settled into being a reasonable stable set of environments - as that suggests that it may actually be quite easy for simple life to form, and we might find a lot of it elsewhere when we start looking properly.

Complex life took a lot longer, though, so could be expected to be very much rarer.

 Martin W 29 Apr 2021
In reply to Doug:

> As its some 20 years old...

Blimey, I bought and read it when it first came out as Life: An Unauthorised Biography.  Scary to realise just how long a go that was...

 Doug 29 Apr 2021
In reply to Martin W:

looking at the cover that's what my copy is called as well - I wasn't quite sure so googled the title (the book was in another room at the time) & it didn't occur to me it might have changed. Worth reading whatever the title

In reply to eaf4:

The remarkable thing is that the Torridonian is virtually unmetamorphosed. The Lewisian below it highly so and the great slices thrust over it are also baked, bent, broken and generally buggered about by the Caledonian and other movements. Apart from a gentle tilt the Torridonian has sat there for a billion years, quietly preserving its fossils, while all this tectonic mayhem was going on.


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