Scott - Oct 25, 2004 4:06 pm - Hasn't voted
Iron conceretionsI believe those are iron concretions, which are present in quatzites and sandstones in the region. When an impurity is in the sandstone, iron particles are attracted to it. The iron concretions are more erosion resistant than the surrounding rock, so what is left it alot of weird dark-colored "bumps" in the rock.
Klenke - Oct 25, 2004 7:55 pm - Hasn't voted
Re: Iron conceretionsThanks, Scott. Sounds good to me. Your analysis corroborates Steve's.
JonBradford - Oct 25, 2004 10:05 pm - Hasn't voted
Re: Iron conceretionsKlenke,
There is one way to verify our speculation... got a magnet?
I would assume iron concretions as well but magnatism is a great indicator of iron content.
Jon
Scott - Oct 26, 2004 7:00 pm - Hasn't voted
Re: Iron conceretionsNope, they don't stick to magnets. There's just some iron in the sand, not enough to stick to a magnet. I have some perfectly round concretions at my house, usually refered to as "Moki Marbles" in Utah.
mdurrant - Jul 5, 2005 4:00 pm - Hasn't voted
Re: Iron conceretions...Worm CastingsThese are common in the Utah limestone formations. They are formed when the substrate was still soft by the organic rich worm dung. Many of these occur from the Bonneville Lake era.
Scott - Jul 5, 2005 5:44 pm - Hasn't voted
Re: Iron conceretions...Worm CastingsLooks like it, I would have to disagree. The core of the Uintas is made of precambrian quartzite about 1.3 billion years old. There is no limestone at all in the core of the Uintas, and I believe the age of the quartzite is much older than worms even existed.
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