1 June 2018
Friday fold: a quartet from Marli Miller’s website
Posted by Callan Bentley
Marli Miller is a senior instructor at the University of Oregon. She is the author of Roadside Geology of Oregon and (with Darrel Cowan) Roadside Geology of Washington. She’s also a very talented geological photographer. She launched a website recently to showcase her work and make it available for instructors: Geology Pics. After chatting with Marli a bit in Flagstaff at the Rocky Mountain / Cordilleran section meetings of GSA a few weeks ago, I got her permission to share a small sample of her lovely fold photos with you here.
Similar folds (passive folding) in marble and quartzite. Rock is of the Plattenkalk Series, Crete, Greece:
Axial planar cleavage and folds in quartzite:
>Proterozoic Banded Iron Formation, folded into asymmetric anticline:
Soft-sediment deformation expressed as folded Pliocene lakebeds of the Coso Formation, SE California:
There are many more awesome fold photos to be seen at Marli’s Geology Pics website, as well as geology themed images on many other subjects. Go check it out and explore!
Thanks for sharing, Marli.
Gotta ask – how can one bed be folded while sandwiched between unfolded beds?
Has to do w/ viscosity contrasts between layers and layer thicknesses.
I assume you’re talking about the last one – this is thought to be soft-sediment deformation, so this was loose sediment slumping.
Yes, the last photo. Slumping do to weight of overlying beds?
Yeah, or just general destabilization for whatever reason (lateral erosion, tilting, jostling by an earthquake…)