Comments on: Geopuzzle: What are these things? (UPDATED)

By: Kyle House

Kyle House — Tue, 08 Dec 2009 01:39:50 +0000

Obviously clay pigeons. Imagine an aghast Kennewick-ish man at shooting practice when a giant flood from Montana rolls in. (?)

Symmetry is troubling for a primary feature. In any case, I want one.

By: lockwooddewitt

lockwooddewitt — Mon, 07 Dec 2009 23:30:16 +0000

Not too far from Howard’s Okanagan Valley, and a similar looking environment.

By: BrianR

BrianR — Mon, 07 Dec 2009 23:24:15 +0000

This site is along the Pend Oreille River near the town of Ione, Washington. Again, sorry about the confusion … but those of you who felt confused can feel good about your geo-instincts!

By: Brian

Brian — Mon, 07 Dec 2009 23:05:24 +0000

Hey everybody … my bad, the site is in NE Washington. Sorry about that.

By: lockwooddewitt

lockwooddewitt — Mon, 07 Dec 2009 21:53:43 +0000

Following up on Andrew’s comment, Missoula Flood beds were what came to my mind as well, but I was and am uncertain that 10 Ka would be enough time to get concretions of that size. Anne, you’ve spent some time looking at this stuff, haven’t you? Have you ever seen concretions in Missoula sediments?

By: Andrew

Andrew — Mon, 07 Dec 2009 21:29:57 +0000

I think you're misleading us by calling this exposure an outcrop of rocks. It looks like floppy sloppy lake beds, or Missoula Flood beds, east of the Wallula Gap. These would be clean silts with a component of fresh basalt particles, which would release calcium and iron promoting cementation. It's hard to tell, but it looks like the concretions are restricted to a few horizons. I'll bet these hockey pucks have very little strength. There would be no diagenesis. I also note that there are several dogbone concretions, where two grew together. People in my forum bring me concretions all the time; I add them to my photo collection.

By: Anne Jefferson

Anne Jefferson — Mon, 07 Dec 2009 21:00:28 +0000

I’m with Lockwood in wanting to know more specifically where these are located, because flat siltstones do not jibe with mental geologic map of Oregon Are we looking at another Anthropocene stratigraphic marker – the skeet-shooting clay pigeon layer?

By: Howard Allen

Howard Allen — Mon, 07 Dec 2009 20:44:20 +0000

Concretions, possibly calcareous, possibly nucleated by mollusc shells (that lowermost object in the third close-up photo looks suspiciously like a clam valve, but maybe just a superficial resemblance). The deposits could be lacustrine; very similar-looking beds with very similar-looking concretions occur in south-central British Columbia (Okanagan Valley); there they are Quaternary lake bed deposits.

By: lockwooddewitt

lockwooddewitt — Mon, 07 Dec 2009 17:53:34 +0000

I’m going with concretions as well. Odd shapes such as these ellipsoids are pretty common. It also looks as if there are distinct horizons where the objects are forming, which is, again, typical for concretions.

My only puzzlement is that in the far NE portion of the state, I don’t know of mudstones/siltstones like this… almost everything is igneous or metamorphic. And almost everything older than the CRB is seriously deformed. Did your reader say more specifically what the location is?

By: quantum_flux

quantum_flux — Mon, 07 Dec 2009 17:38:03 +0000

….oh, the round ones look like river rocks of some sort, perhaps rounded out cement from abrasive silty erosion from upstream?