Awesome, thanks for sharing
Great photo, thanks for sharing
Wuts a tafoni?
Just one tafone pls, I’m driving
https://www.nps.gov/articles/tafoni.htm
if you had typed your post into the address bar this is literally the first result
..Sir this is a Wendy’s
if you had typed your post into the address bar this is literally the first result
God forbid we might discuss it on the geology subreddit, eh?
It’s worth some further consideration at least, given that (despite what that NPS link says) tafoni isn’t always well defined or at least doesn’t always seem to refer to exactly the same process. There is the honeycomb tafoni that the term often refers to, then there is also the the large tafoni that occur as singular hollows carved into rock. This is the origin of the term in fact, when it was used to describe the hollows carved into granite boulders on the island of Corsica eg. this bad boy.
The NPS page emphasises the dissolution aspect, but the granite boulder exampke should be enough to tell us that isn’t the whole story. Tafoni more akin to OPs examples also occurs in sandstones with little to no calcareous cement, particularly in arid environments, something noted by geologists like Eliot Blackwelder and Kirk Bryan around 100 years ago:
”The cavities have also been explained as the effects of solution. It is significant, however, that they are rarely found in limestones and other soluble rocks, but are common in rocks that contain little soluble material.”
Both of those factors (arid environments + non-soluble rock) would seem to indicate something other than dissolution is going on, at least in some cases. Most important seems to be strong temperature variances (possibly involving freeze-thaw action, but could be just strong heating-cooling cycles) and salt/sand blasting from the wind. Once a depression is initially formed, cavities will become foci for salt accumulations and further salt weathering. This sort of process then explains why tafoni also occurs in coastal environments.
I think as it stands, it’s not clear whether the salt action I’ve described above is promoting selective chemical attack, or whether it promotes purely physical weathering with crystals effectively prising apart the rock grains. Even if not via chemical dissolution, water is probably involved to some extent - a lab study to recreate tafoni type weathering certainly makes it look that way anyhow.
I think probably there is not a one-size-fits-all answer as to the exact process(es) involved, though I would be happy to be set straight by anyone who knows more.
Thanks bro!
No worries. I found a decent review paper with quite a lot to say about tafoni if you have access:
I LOVE TAFONI RAGHHHHH!
SP?
Salt Point State Park, California
Thanks! These are beautiful outcrops.
Ah yes Arrakis the Desert Planet
Needs banana, I have no idea how to perceive these images.
Forbidden ravioli
So cool!
https://imgur.com/a/s56r1us
Me in my younger days, ha ha. Shore Acres state park. Southern Oregon coast. Coos county.