You don't need a geologist Jan, from what I recall you convert geologists who think RA is all natural into being avid cup spotters ;)
Apparently when you get the concave areas in between the harder striations, there's a process called arenisation which accelerates the hollowing effect. Seems it's what's responsible for a lot of the freaky shapes in Millstone grit. I'm not sure it happens in metamorphic rock though, and I've the vague sense that most of Aberdeenshire is metamorphic. So I'm just waffling here really. I'll shut up.
Hi Drew,
Nature does strange things to (sand) stone over the millions of years being exposed to the elements.
The stripes in the sandstone are most probably caused by layers of different -obviously harder- sediment.
It could point to fires or a (very) long period of dryness.
But these are all rough guesses!
We hope for an explanation by a geologist!
Cheers,
Jan
You don't need a geologist Jan, from what I recall you convert geologists who think RA is all natural into being avid cup spotters ;)
Apparently when you get the concave areas in between the harder striations, there's a process called arenisation which accelerates the hollowing effect. Seems it's what's responsible for a lot of the freaky shapes in Millstone grit. I'm not sure it happens in metamorphic rock though, and I've the vague sense that most of Aberdeenshire is metamorphic. So I'm just waffling here really. I'll shut up.