Very nice, Bob but why are the stones picking up the colour of the road? It looks really wrong.
I think it's because you have either got the stones before the road shader in your network and the colour isn't blended out where the road overlaps them OR, that you have slope constraints set in the stones layer and forgot to select 'terrain normal' as the slope key so the stones are still picking the underlying colour up.
Other than that, pretty cool!
You might rather these cirrocumulus clouds, I updated them a while back because I thought they were too harsh and the patterns a bit repetitive. Give v.2 a go, they look like this, not so sharp...
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And clipfile... [attachimg=#]