tag:blogger.com,1999:blog-3728725441575309638.post5934021539938335730..comments2023-10-30T08:13:43.200-07:00Comments on Questioning Answers In Genesis: Dispelling a few myths about Steve Austin's cave dissolution modelChemostrat1646http://www.blogger.com/profile/01067579479402100587noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-3728725441575309638.post-11466281006908857602011-08-26T15:03:47.687-07:002011-08-26T15:03:47.687-07:00Steve, I apologize that I did not give you enough ...Steve, I apologize that I did not give you enough credit in that response. You are absolutely right in pointing out that much of the Ca lost to groundwater is ultimately derived from the bedrock (regardless of the relative contribution from dust/rain). I should have been more clear in the article and in my response. Thanks again for your comment.Chemostrat1646https://www.blogger.com/profile/01067579479402100587noreply@blogger.comtag:blogger.com,1999:blog-3728725441575309638.post-83524509100870194622011-08-25T17:49:04.675-07:002011-08-25T17:49:04.675-07:00Thanks for your feedback, Steve. Calcium cycling i...Thanks for your feedback, Steve. Calcium cycling is a complicated topic, which I have admittedly simplified here. But I am relying on several recent papers that have tried to quantify Ca fluxes in forested ecosystems (e.g. Holmden and Belanger, 2010 and references therein). Ca loss to groundwater from soil, even in forested ecosystems with silicate bedrock, is pretty substantial and should be considered in any models.<br /><br />But your objection is rather about the ultimate source of Ca in soil. In the long term (steady-state models), as much as 50% or more of Ca lost to groundwater is ultimately derived from wet and dry atmospheric deposition (the actual percentage depends on the geography/climate of the region). Wind-blown dust and dissolved Ca in rain is small in terms of concentration, but constitutes a large external source to the system. Therefore, one cannot say that all dissolved calcium is derived from the bedrock.<br /><br />Since the Ca loss to groundwater is greater than atmospheric deposition, Ca tends to decrease in soils over time. Conversely, the loss of exchangeable Ca in soils over time verifies that soil-derived Ca is an important source to groundwater.Chemostrat1646https://www.blogger.com/profile/01067579479402100587noreply@blogger.comtag:blogger.com,1999:blog-3728725441575309638.post-11933457980843956372011-08-25T13:55:03.818-07:002011-08-25T13:55:03.818-07:00I think your analysis of calcium flux is flawed. Y...I think your analysis of calcium flux is flawed. Yes, much of the calcium is leached from the soil or vegetation, but since that calcium is ultimately derived from the bedrock, it's legitimate to exclude it only if there's a huge non steady state amount locked away in soil and vegetation somehow. If the landscape is steady state then the dissolved calcium is all derived from the bedrock.Steve Dhttps://www.blogger.com/profile/10306339430255071009noreply@blogger.comtag:blogger.com,1999:blog-3728725441575309638.post-25434988943518610862011-08-15T18:51:05.556-07:002011-08-15T18:51:05.556-07:00Good points. My understanding is that a cave netw...Good points. My understanding is that a cave network starts in weak points in the limestone, and grows from there (so much for "assuming present rates and conditions!). This happens at multiple levels - not just one as many YECs envision. One look at all the different levels shown in a 3-D map of Mammoth Cave kind of blows apart the idea that it formed through the simple mechanism Austin described.<br /><br />I've been told that the hydrology of karst areas is a nightmare for National Weather Service hydrologists who have to forecast rivers in the Mammoth Cave and similar areas. The exact route the water lost in sinkholes takes underground isn't always known, introducing uncertainty when you have to predict which part of rivers will flood when local heavy rainfall occurs.<br /><br />I drove out to Sinking Creek in Kentucky to see the location where the data was taken that Austin used. I ran into the owner of the land immediately to the south of where the terminating sinkhole is for the creek, and he took me to where it was located. The cave entrance looked like it was only a few feet high. He said when they get a real good storm (e.g., 3" plus), the water backs up in the sinkhole like it would in a slow draining bath tub and takes several hours to empty out.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-3728725441575309638.post-43804296175293083562011-08-15T18:29:53.292-07:002011-08-15T18:29:53.292-07:00Thanks, Tim, for keeping me honest. :) I subtly tr...Thanks, Tim, for keeping me honest. :) I subtly tried to avoid talking about direct infiltration through sinkholes and other conduits because it makes any quantitative discussion too complicated (esp. without more detailed geographic data from the region). But you are right. Presumably, much of the water that actually carves out the cave enters in this manner.<br /><br />On the other hand, sinkholes only cover a small percentage of the landscape, but Austin envisaged 82% of the total precipitation entering the cave system as slightly acidic, highly undersaturated rainwater. I don't mean to speculate, but I can't imagine how 82% of annual precipitation could bypass soil/vadose zones altogether. Either way, this question is worth following up in recent literature, which may have more detailed figures on cave flowthrough.<br /><br />Lastly, before 'sinkhole infiltration' is a viable factor, sinkholes themselves must form, and this occurs by much slower infiltration through soil, regolith, joints, etc. When all steps are considered, I believe one of the steepest challenges—and most easily understood—to the Creation Museum lies in its own backyard.<br /><br />Thanks again for the feedback!Chemostrat1646https://www.blogger.com/profile/01067579479402100587noreply@blogger.comtag:blogger.com,1999:blog-3728725441575309638.post-7843993376695230242011-08-15T11:25:37.303-07:002011-08-15T11:25:37.303-07:00Good post, John. You introduced some information ...Good post, John. You introduced some information that I didn't cover in "deceptive tactic #6" in my presentation "Are the Young Earth Creation Ministries Shooting Straight With Us" at http://www.slideshare.net/TimH/are-the-creation-ministries-shooting-straight-with-us-part-1. While I think Austin's use of an encyclopedia to obtain the amount of water entering the aquifer was rather sloppy scholarship, I think the actual amount is probably closer to Austin's number than yours. Evapotranspiration (ET) numbers are derived from in-depth studies of small watersheds (on the order of a few acres or less) where the moisture input and plant cover are relatively uniform. In the Mammoth Cave area, most of the water enters the cave system from sinkholes at the surface (e.g., see top photo on this website: http://www.karstwaters.org/educationlinks/karst.htm. I doubt if the ET numbers calculated for small study watersheds in Kentucky took into account the loss of water into sinkholes.<br /><br />Actually, I think the loss of surface runoff into sinkholes was the biggest "hole" in Austin's analysis. In a 1971 article in the Journal of Hydrology by Evan T. Slusher and William B. White, the authors found that most water passing through a cave network enters during major rainfall events, when there is no chance to dissolve calcium and magnesium to the concentrations identified by Austin. (This J. of Hydrology article came out 1 year prior to the J. of Hydrology article Austin used to obtain his average Ca and Mg concentrations -- too bad he didn't use it!) During heavy rainfall events, we see water gushing from the outlets of cave systems along side rivers, indicating a pretty rapid throughput. I think this plus "assuming present rates and conditions" were the big flaws in Austin's analysis.Anonymousnoreply@blogger.com