Saturday, September 10, 2011

Fold Analogs

After spotting the folds in meta-argillite up on Wheeler, I came across these distorted, fold-like growth bands in an old tree stump. These "folds" are quite variable, ranging from gentle to tight. They are locally similar, broadly disharmonic. Maybe Callan could describe them a little better than that!
Two small "folds" that are slightly overturned to the east.

5 comments:

off_the_shelf_edge said...

wow, that is pretty cool. i wonder what makes the roots fold like that, growing up against rocks? it would be a really cool analog picture to find a tree stump growing all folded right up against a folded metamorphic rock :)

Silver Fox said...

I don't know what causes the distortions, but they are common in old junipers everywhere (and other trees - these may be limber pine) and in the Bristlecones higher on the mountain.

Next time I'm up there (probably not until next summer), I'll have to look for one of these next to a folded rock!

Gabe J said...

I found some cool folds the day before yesterday too! This is straight from the sides of the Erta Ale volcano in Ethiopia https://picasaweb.google.com/105848048633478205070/20110916GeotourErtAleAndDallol?authkey=Gv1sRgCNib5v-a2Ln8gwE#5653013256638135458
And the whole album in case you are interested, there is tons of ridiculous geology especially at the end of the album (Dallol)
https://picasaweb.google.com/105848048633478205070/20110916GeotourErtAleAndDallol?authkey=Gv1sRgCNib5v-a2Ln8gwE

John Lamerand said...

In rocks this kind of disharmonic folding might indicate that the folds formed during soft sediment slumping, and in that way they are also similar to the folds that you sometimes see in Chromitite near the "plumbing end" of a Chromitite sill. There are many trees in Western Australia that share this kind of grain, just as an aside.

Silver Fox said...

@Gabe, thanks for the links to primary volcanic folds (photos).

@John, I'm not terribly good at identifying soft sed slumping, and the rocks I work in often show later deformation that confuses the issue! Would love to see photos of a chromitite sill.