tag:blogger.com,1999:blog-7563205518828267408.post1167135656249857887..comments2024-01-19T08:08:23.595-08:00Comments on All of My Faults Are Stress-Related: Sunday stroll: UFOs and alcovesKimhttp://www.blogger.com/profile/07738706550175991130noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-7563205518828267408.post-60720445305380738172008-03-24T13:05:00.000-07:002008-03-24T13:05:00.000-07:00You piqued my interest; I had to look around for c...You piqued my interest; I had to look around for carbonic acid's part in enhancing erosion in calcite-cemented sandstones. When gw surfaces, it combines with CO2 to form carbonic acid which, in turn, enhances the erosion process by dissolving the calcite cement. I hate to think of how the Ancient Puebloans teeth looked after 35 years of alcove/metate sand. <BR/><BR/>http://ohwm.blogspot.com/coconinohttps://www.blogger.com/profile/12050625735753145388noreply@blogger.comtag:blogger.com,1999:blog-7563205518828267408.post-10996428267933541812008-03-24T12:43:00.000-07:002008-03-24T12:43:00.000-07:00I would argue that there is a combination of both ...I would argue that there is a combination of both overland flow and sapping for most alcoves. Monsoon events in the desert southwest, even for small catchments, will produce considerable overland flow (occasional inch/hour storms can be frequent as was the norm during monsoon 2006). I seem to recollect that the overland flow during brief intense storms is of the Hortonian type, where the surface essentially seals and very limited infiltration occurs. Also could there be a synergistic effect between normal weathering and gw surfacing to enhance the solution of the gypsum or calcite cement?<BR/><BR/>http://ohwm.blogspot.com/coconinohttps://www.blogger.com/profile/12050625735753145388noreply@blogger.comtag:blogger.com,1999:blog-7563205518828267408.post-14460103776769606382008-03-24T11:50:00.000-07:002008-03-24T11:50:00.000-07:00Oh, interesting! Thanks for pointing that out.Now ...Oh, interesting! Thanks for pointing that out.<BR/><BR/>Now I really wish I had taken a picture. This particular alcove was tiny - my son wouldn't be able to crawl into it - and was no more than three feet below the top of the (tiny) cliff. The catchment area for any overland flow would have been pretty small (especially compared to places like Mesa Verde).<BR/><BR/>What would you look for? Is there a minimum amount of water necessary to drive the erosion?Kimhttps://www.blogger.com/profile/07738706550175991130noreply@blogger.comtag:blogger.com,1999:blog-7563205518828267408.post-12691755216831424852008-03-24T11:17:00.000-07:002008-03-24T11:17:00.000-07:00There are those that dispute that sapping is an ef...There are those that dispute that sapping is an effective process in bedrock. They argue that in every alcove (or at least every amphitheatre headed valley) they observe, that there was evidence of overland flow and plunge pool erosion. See Lamb et al. 2006. "Can springs cut canyons into rock?" JGR. E07002, doi:10.1029/2005JE002663ScienceWomanhttps://www.blogger.com/profile/11252480538852802610noreply@blogger.com