tag:blogger.com,1999:blog-8712540294522210240.post5743245587212671570..comments2024-03-06T22:08:30.648-08:00Comments on The Dynamic Earth: ChugwaterErichttp://www.blogger.com/profile/01969672173684293621noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-8712540294522210240.post-84300909670025934872009-04-24T07:09:00.000-07:002009-04-24T07:09:00.000-07:00Howdy George! My interp of the Alcova as lacustri...Howdy George! My interp of the Alcova as lacustrine comes from me boppin' around the Chug for a few days, and I thought it looked awfully lake-y. Of course, I'm working in the Green River Fm for my PhD, so those carbonate lake phases might be coloring my worldview, too. <br /><br />I havn't read your work, but I guess I'll have to, now! I know Picard always interpreted the Alcova as a shallow marine tounge, so it's nice to know that someone out there has done the work and come up with an alternative interp.Erichttps://www.blogger.com/profile/01969672173684293621noreply@blogger.comtag:blogger.com,1999:blog-8712540294522210240.post-53509759172234186202009-04-22T13:42:00.000-07:002009-04-22T13:42:00.000-07:00Eric: On what do you base your decription of the A...Eric: On what do you base your decription of the Alcova limestone as a phase of shallow-water, carbonate-rich lake sedimentation. Is it possible that you have read my PhD dissertation? George F. C. University of Missouri prophiting@yahoo.comAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-8712540294522210240.post-65184946952745895382008-06-22T09:26:00.000-07:002008-06-22T09:26:00.000-07:00Thanks for the explanation, Eric. I appreciate it...Thanks for the explanation, Eric. I appreciate it. I found another place with similar concretions.Juliehttps://www.blogger.com/profile/16365431147428816749noreply@blogger.comtag:blogger.com,1999:blog-8712540294522210240.post-39767266210502058762008-06-21T07:42:00.000-07:002008-06-21T07:42:00.000-07:00Hi Julie! Sorry for contributing for your suspens...Hi Julie! Sorry for contributing for your suspense, but I'm only coming into town around once a week to stock up on supplies and get my internet fix. <BR/><BR/>Anyway, the little balls you found in the sandstone are not only iron-like, they are, in fact, iron. <BR/>Iron in fluids moving through the sandstone resulted in localized precipitation of what are called concretions. These little iron concretions formed in place, within the sandstone, after the sand had been deposited and buried.<BR/><BR/>Concretions have recieved a lot of attention, mostly in the field of geochemistry, where the fundamental question of why these things form where they form is still a big research area. Generally, it's believed that the iron-rich fluids encounter a localized micro-environment in the sandstone that results in extremely localized precipitation of iron-rich mineral phases in the area, often as a cement. The cement grows outward from a nucleus, and viola! You get concretions!Erichttps://www.blogger.com/profile/01969672173684293621noreply@blogger.comtag:blogger.com,1999:blog-8712540294522210240.post-29561720221057122872008-06-18T09:46:00.000-07:002008-06-18T09:46:00.000-07:00Hi Eric,I was just out to Alcova last Sunday, and ...Hi Eric,<BR/><BR/>I was just out to Alcova last Sunday, and we hiked around the canyon there. Embedded in the sandstone layers were these strange iron-like balls (much heavier than surrounding rock, with a deep purple and rust color). They are not eroding as fast as the surrounding sandstone. I'm perplexed as to what they are. My theory (having a very limited education in geology) is they are some sort of debris from a meteoritic impact? Do you know what they are? The question has been bothering me for days now.Juliehttps://www.blogger.com/profile/16365431147428816749noreply@blogger.com