Op 25/09/2023 om 22:20 schreef Samuel B.:
> Thomas de Groot <tho### [at] degrootorg> wrote:
>> While digging through my archives I came across a couple of macros I
>> wrote back in 2006, inspired by textures devised by PM 2Ring [...]
> 
> Those are what you attached? The cross-bedded sandstone material looks very
> good.
> 
Yes they are indeed (i.e. attached, and very good) ;-)


>>> The links you posted are quite inspiring. The first image in the first link is
>>> something I've tried to do, but always seem to fail at. Later on that page, I
>>> was amazed to see that sand ripples could be captured in such a way.
>>>
>> Yes, amazing, isn't it? Those things are what have always attracted me
>> in sedimentary geology. And to realise that those same features can also
>> be found as far back as deep into the Precambrian, more than 4 billion
>> years ago, before even life took hold on this planet...
> 
> Yeah... And to think, one could also find such things (and even
> never-before-seen things) on different planets and moons. Differences in
> gravity, atmospheric pressure, heat level and dissipation, primary erosive
> liquids... these could all create geology quite a bit different than what we see
> here on Earth.
> 
Yes, I thought about that too. There are definitely (rippled) sand dunes 
on Mars, very similar to Earth's despite a much thinner atmosphere. I am 
not sure, but I seem to remember that the few photographs we got from 
the surface of Titan in 2005 showed some tell-tale sedimentary 
structures. At least there are wind-blown dunes and "river" systems in a 
really alien landscape where water is replaced by hydrocarbons... And 
indeed, we can already predict that any planet we discover outside the 
Solar System (James Webb telescope) which has an atmosphere will also 
show very similar sedimentary processes and structures on its surface in 
accordance with its own particular chemistry.

-- 
Thomas

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