<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; charset=US-ASCII"> <META content="MSHTML 6.00.6000.16674" name=GENERATOR></HEAD> <BODY id=role_body style="FONT-SIZE: 10pt; COLOR: #000000; FONT-FAMILY: Arial" bottomMargin=7 leftMargin=7 topMargin=7 rightMargin=7><FONT id=role_document face=Arial color=#000000 size=2> <DIV>Back about a month ago, we learned of the publication of a paper titled "Climate-induced variations of geyser periodicity in Yellowstone National Park, USA", authored by Hurwitz, Kumar, Taylor and Heasler. The appearance of that paper, and discussions resulting from that, read (in essence): "How do they date geyser water, and where did the figure of '500 years' come from."</DIV> <DIV> </DIV> <DIV>Via Ralph Taylor, co-author Hurwitz provided an answer, namely: " In short answer to...[the] question ... 'OF's water supply is about 500 years old' -- I don't know how that info came about." </DIV> <DIV> </DIV> <DIV>Well... since my book(s) would seem to be one source of the "500 years" statement, a huge exclamation point could be part of my answer to Hurwitz. I have held this response for my return to my full library here in Arizona.</DIV> <DIV> </DIV> <DIV>In my short answer, check USGS publications by such rather well-known authorities as Truesdell, Fournier, Christensen, and White.</DIV> <DIV> </DIV> <DIV>A primary source, which I cite here, is:</DIV> <DIV>Rye, R. O. and Truesdell, A. H., 1993, The question of recharge to the geysers and hot springs of Yellowstone National Park, USGS Open-File Report 93-384.</DIV> <DIV> </DIV> <DIV>I acknowledge first that a complete lack of detectable tritium in water shows only that it is "older" than 60 years. (Well, the paper in question here seems to say 50 years while all these other USGS things say 60 -- but what's 20% or so when the authors admit they "enhance the signal-to-noise ratio" by "filtering [to eliminate] 15% of the [Old Faithful] intervals from the data set" -- as several people versed in math and statistics, as well as geysers, said upon seeing that: "WHAT!?!?!")</DIV> <DIV> </DIV> <DIV>Sorry, I digress... In the Rye and Truesdell article are the following items (as samples):</DIV> <DIV> </DIV> <DIV>-- the deep reservoir residence time of most of the thermal water "should" be less than 1900 years</DIV> <DIV> </DIV> <DIV>-- the discharge from the deep reservoir is [approximately] 7.5 X 10^10 kg/yr, and per the chloride inventory the residence time is between 370 and 1900 years.</DIV> <DIV> </DIV> <DIV>-- the above is consistent with water-rock reactions AND with a recoil model for radium isotope supply that yields a maximum of 1150 years. {NOTE: It is in another paper that unfortunately I am unable to locate at the moment in which Friedman states that this value is a "best guess figure" for recharge rate.}</DIV> <DIV> </DIV> <DIV>-- However, the above authors note that, if the deep reservoir is replenished from multiple sources, then the oldest deep geothermal component(s) could well be as "old" as 10,000 years.</DIV> <DIV> </DIV> <DIV>-- Finally, the authors hypothesize that there could well have been a major influx of water to the geothermal system during the "Little Ice Age" of the 15th century -- that is, at a time somewhat more than... errr... 500 years ago.</DIV> <DIV> </DIV> <DIV>I will also point out to the authors that they apparently missed one reference to the matter of surface water influences, supporting my initial reaction to the article of : "Duh." This is:</DIV> <DIV>Marler, G. D., 1964, Seasonal changes in ground water in relation to hot spring activity; Am. Jour. Sci, v.262, May 1964, p.674-685.</DIV> <DIV> </DIV> <DIV>Enjoy.</DIV> <DIV> </DIV> <DIV>T. Scott Bryan</DIV></FONT><BR><BR><BR><DIV><FONT style="color: black; font: normal 10pt ARIAL, SAN-SERIF;"><HR style="MARGIN-TOP: 10px">Gas prices getting you down? Search AOL Autos for fuel-efficient <A title="http://autos.aol.com/used?ncid=aolaut00050000000007" href="http://autos.aol.com/used?ncid=aolaut00050000000007" target="_blank">used cars</A>.</FONT></DIV></BODY></HTML>