Article 20512 of talk.origins: Newsgroups: talk.origins Path: klaava!hydra!news.funet.fi!fuug!mcsun!uunet!nntp1.radiomail.net!fernwood!aurora!isaak From: isaak@aurora.com (Mark Isaak) Subject: Response to the Response to the Flood FAQ, part 2 Message-ID: <1992Dec31.184608.6523@aurora.com> Reply-To: macrae@pandora.geo.ucalgary.ca (Andrew MacRae) Organization: The Aurora Group Date: Thu, 31 Dec 92 18:46:08 GMT Lines: 279 [More contributions from Andrew MacRae, who himself can't post.] > folta@cs.umd.edu (Wayne Folta) [lots of deletions] >> How do you explain the formation of varves? The Green River formation >> in Wyoming contains 20,000,000 annual layers, or varves, >> identical to those being laid down today in certain lakes. >> [From: bill@bessel.as.utexas.edu (William H. Jefferys)] >In Whitcomb & Morris, ("The Genesis Flood"), pages 424-428 talk about the >Green River formation. The book was written in 1961, so things may have >changed, but it says that the only real study of the formation was made >more than thirty years before that by Bradley, with all other papers >pointing back to this one. The Green River Formation is still actively studied today. Especially because of the economic potential of the substantial oil shale deposits. >They say that the 6 million years (to deposit) figure was based on >Bradley's estimates of an ancient drainage basin's size, slope, character, >erosibility, drainage characteristics, and the amount of water available. Well, of course these affect it. So? Is there any evidence that the estimates Bradley made were off by, say, several orders of magnitude (6000 versus 6 000 000)? Or are we talking about a variation of "only" 50% (3 000 000 years)? >They also say that the Green River formation has layers that are too thin >and too uniform over too wide an area to have been deposited in a normal >lake bed. What an insight! Yes, it was a _big_, _deep_ lake, not a "normal" lake. The Green River Formation occurs over a very large area. >That is, there are no signs of any stirring up of the sediments or of any >deposits that reflect flooding conditions where large amounts of sediment >would have been dumped into the lake and would have sorted out in graded >series. Man, haven't these guys heard of "proximal" versus "distal" sedimentary environments? Proximal is nearshore, near the sediment sources. Distal is away from the shore, in the central, deep part of the lake, below the influence of waves, and well away from the front of active deltas. Think of proximal environments as "on the beach", and distal as "out to sea". Clearly the varves were deposited in the centre of the lake, in distal sedimentary environments - not near shore, because the wave activity and high sediment influx near the shore would interfere with the deposition of the thin, continuous layers. This still leaves a problem, since the normal lake infauna (worms, clams, etc.) would burrow in the sediments and disturb the varves. However, it is not uncommon for lakes (especially large, deep ones) to become stratified - that is, have an oxygenated, warm water layer near the surface; and a cool, anoxic (little or no oxygen) bottom layer. What happens to the infauna at the bottom of the lake in the anoxic layer - it dies. In fact, variations in the vertical position of the anoxic layer is thought to be the reason for the massive fish kills that periodically produced the beautiful fish fossils from the Green River Formation (they occur in the varved sediments). The anoxic conditions are perfect to suppress the decay of the animals that fall into the lake, allowing them to be preserved over thick intervals of rock. >They have pictures of true lake deposits and of the Green River shales, >and the difference in appearance is dramatic. From this, it seems to me >that the Green River deposits are not what they claim... That a lake sould >not have been so still and undisturbed form six million years that there >is no sign in the formations. See above. Their "dramatic difference" is the difference between proximal and distal lake environments. Note that in a small lake, all you may see is the proximal environments, because you are always close to shore. Morris et al. should go snorkelling in a large anoxic lake sometime. Besides, the Green River Formation is not just the varved shales (which really would be anomalous). It also contains the nearshore, more proximal facies (rock types), including terrestrial river channels and shallow lake deposits. The proximal facies laterally intertongue with the varved, distal shales, exactly as predicted. Also as predicted, the proximal deposits are better oxygenated, and contain bottom dwelling faunas, like snails and clams. You can see these deposits along the road cuts in Spanish Fork Canyon, Utah, southeast of Salt Lake City [Rigby, J.K., 1968. Guide to the Geology and Scenery of Spanish Fork Canyon Along U.S. Highways 50 and 6 Through the Southern Wasatch Mountains, Utah. Brigham Young University, Geology Studies, v.15, part 3, p.1-31]. A more serious problem with the short amount of time used by some flood models is the wide lateral area of deposition. There are millions of individual varve layers. It does not matter whether they are one year for each varve, you still must make millions of laterally continuous layers by some sort of event that takes a finite amount of time. The sedimentology puts some constraints on the rate. The varves are composed of very fine material - clay-sized organic and mineral grains - that is graded into alternating mineral-rich and organic-rich layers. The water must be slow moving for the fine-grained material to settle out, and in order to leave the underlying layers undisturbed. Additionally, you must spread this fine-grained layer over many hundreds of square kilometres, allowing the minerals (more dense) to settle first, followed by the organics (less dense). In modern environments, such laterally continuous laminations take months to form (at least). Even if you make a _ridiculous_ assumption, and say each varve could form in a few minutes over hundreds of square kilometres, you are still dealing with much longer than some flood creationist models propose. How many minutes in a year? 60X24X365=525600, i.e. about half a million. So, even with these _ridiculous_ assumptions, the deposition of 20 million Green River Formation varves took almost 40 years - and this is only one of many older and younger formations, including varved ones!! A good example is the mm-thick laminae of alternating, very fine-grained calcite and anhydrite ("dehydrated" gypsum) in the Permian Castile Formation, Texas [Anderson, R.Y., Dean, W.E., et al., 1972. Permian Castile varved evaporite sequence, west Texas and New Mexico. Geological Society of America, Bulletin, v.83, p.59-86]. Individual laminae are traceable over tens to hundreds of kilometres. Similar laminated carbonates and evaporites occur in Alberta. Producing these units by catastrophic, rapid processes is very difficult to envision - especially evaporites (anhydrite, gypsum, salt). If you start using reasonable lower limits on a varve's formation - say, a few hours, days, or even months - the duration for the formation becomes correspondingly much longer. So, it does not matter if 1 varve = 1 year exactly - the total duration is still a long time. In fact, in the Dead Sea, one varve lamina is deposited every three or four years. If you restrict the deposition of all the varves to the 1 year total duration of flood models, you must deposit a varve in a few seconds (assuming you have all year - not taking into account other, thicker rock formations). This does not jive with the physics of fluid mechanics. This sounds very supernatural to me. -Andrew macrae@geo.ucalgary.ca