Moki Marbles

You may have noticed a theme in my recent postings... these are all from a new series I am working on from the Southwest, photographs made over the past year. I'm hoping to get the whole body of work up on my site in the next week or so.

These are Moki Marbles in Harris Wash, near Escalante. 30D, 17-40 L, processed in Lightroom.

If anyone can explain how these are formed I'd be happy to hear it...

I really like this one. I wonder what the color version looks like.

Moki Marbles are such fun subjects! One of these days I'm going to get out there and find some of my own.

These "marbles" are just iron rich concretions. If you look around you will probably find them weathering out of nearby sandstones, uphill. The Jurassic, Navajo Sandstone seems to be the dominant host rock. Apparently the porosity and permeability of these dune sands is especially suited to iron concretion precipitation. They certainly are capable of transmitting a LOT of fluid.

See pages 8 through 11 in this pdf for some additional details on the chemistry. Page 11 as a condensed summary:
http://geology.utah.gov/online/pdf/pi-77.pdf

Bill - it's so funny, when I wrote that, the first thing I thought is "I wonder if Bill will answer this"?

I heard that you and my dad (Edward Coalson) used to work together at Amoco?

Small world...

You're kidding me! Your dad is Ed!!!!!!!!!!!!! One of the best petrophysicists that I have had the pleasure to work with.

So, how is it that you didn't already know the answer to your question?

Bill, I will email you... but I never asked my dad about Moki Marbles...

I just assumed that you had the equivalent of a graduate degree in geology before entering high school.

A very cool image, Nat.

Very nice, Nat. I like the high-key treatment as it strengthens the graphic qualities of the image. Nice work with the comp, too. I imagine this looks phenomenal in print!

Wow, and here I thought they were just elk droppings!