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Member (Idle past 5937 days) Posts: 3435 From: Edmonton Alberta Canada Joined: |
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Bill Birkeland Member (Idle past 2561 days) Posts: 165 From: Louisiana Joined: |
sidelined wrote
>Ok so let us crunch the numbers shall we? ...text deleted... >Anyway we shall go to>http://polarmet.mps.ohio-state.edu/...tracts/abs.CBV.97.html >for this data on Antarctica. > >For the eleven year period 1985-95, the average >continental value is 151 mm yr-1 water-equivalent. > >151 mm into 3 miles or 4.8 km > >4.8 km = 4,800,000 mm >divded by 151 mm = 31788 years As the snow is buried, it goes from snow to firnto ice. In this process, the volume of the initial snow layer is decreased. Also, with depth, there is some thinning of the ice due to stretching from spreading of the ice sheet. As a result, any layers become thinner with depth. Thus, a simple linear extrapolation will greatly underestimate the time it took the ice took to accumulate. To get an accurate estimate, the changes in volume of the snow /ice as it is buried and thinning due to stretching need to taken into account. Other web pages on the Lost Squadron: Ice Core Dating by Matt Brinkmanhttp://www.talkorigins.org/faqs/icecores.html Feedback for July 2003TalkOrigins Archive - Feedback for July 2003 Claim CD410:CD410: Airplanes Buried in Ice Rescue of the Lost SquadronHTTP 429 Yours, Bill Birkeland [This message has been edited by Bill Birkeland, 10-08-2003]
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Bill Birkeland Member (Idle past 2561 days) Posts: 165 From: Louisiana Joined: |
Coragyps wrote
"After some exhaustive Googling, partlyin Danish, I have found that the average annual snowfall along the SE coast of Greenland ranges from about 150 cm (as water - much more as depth of snow) to 247 cm. Compare 25 cm at Summit, where the GRIP and GISP2 cores were drilled. That's 6 to 10 times as much." Information, including maps, about the variation of snow accumulation across all of Greenland can be found at the below web pages. 1. Bales et al. (2001a) snow accumulation map for Greenlandhttp://www-bprc.mps.ohio-state.edu/...racts/BALESGRLFIG5.jpg 2. Bales et al. (2001b) snow accumulation map for Greenlandhttp://www-bprc.mps.ohio-state.edu/...bstracts/BALESFIG3.jpg 3. Bales, R. C., McConnell, J. R., Mosley-Thompson, E., and Csatho, B., 2001a, Accumulation over the Greenland ice sheet from historical and recent records. Journal of Geophysical Research (Atmospheres). vol. 106(D24), no.33, pp.813-33,825. http://www-bprc.mps.ohio-state.edu/...tracts/bales-jgr-1.pdf 4. Bales, R. C., McConnell, J. R., Mosley-Thompson, E., and Lamorey, G., 2001b. Accumulation map for the Greenland ice sheet 1971-1990. Geophysical Research Letters, 28(15), 2967-2970 http://www-bprc.mps.ohio-state.edu/...s/Bales2001GRL-Aug.pdf 5. PDF files of publications on Green land climatologyhttp://www-bprc.mps.ohio-state.edu/...stracts/Abstracts.html 6. Snow Accumulation at GISP2 Summit, GreenlandPage not found - The University of Maine 7. NASA Greenland FiguresPage not found | Department of Hydrology & Atmospheric Sciences ++++++ Antarctica Climatic Data and information +++ Information about the net snow accumulation and other climatic data for Antarctica can be found in the below web pages: 1. The mass balance of Antarcticahttp://www.nbs.ac.uk/public/icd/ant.mass.bal.html "The surface mass balance is generally agreed to be about 150 mm/y (plus or minus up to 20%, though the degree of accuracy is, of course, unknown too; also, the value is not constant in time) (averaged over Antarctica, but with very wide variations from more than 1000 mm/year to less that 50 mm/year in the interior to some smaller areas with average net loss). 2. [WMC's] Climate information for AntarcticaClimate information for Antarctica and Climate Data for Antarctica Examples of Snow Accumulation Datasets for Antarctica: http://www.antarctica.ac.uk/met/climate/wmc/dgv-surfbal.gif http://www.antarctica.ac.uk/...climate/wmc/cg-global-acc.gif http://www.antarctica.ac.uk/met/climate/wmc/gio-dgv.gif 3. Antarctica WeatherPage not found - British Antarctic Survey Page not found - British Antarctic Survey Page not found - British Antarctic Survey Yours, Bill Birkeland
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Bill Birkeland Member (Idle past 2561 days) Posts: 165 From: Louisiana Joined: |
sidelined wrote:
"I do hope I wasn't angering you withthe crudity of my "number crunching." No problem. Your number crunching was neither "angering" nor "crude." I noticed that people were discussing the accumulation rates of snow in Antarctica and Greenland and thought that I might give a head's up to people where they can find such data. I had found the URLs related to this subject, while doing something else, and just thought I might pass them on so people would have some real data with which to do number crunching and just have fun discussing. For example, it is a fun amd instructive exercise to print out the map showing the accumulation rates of snow in Greenland and plot the approximate location of where ices cores have been taken and the location where the Lost Squadron was found. If someone has the time, maybe they can create and post a figure of this exercise. Yours, Bill Birkeland [This message has been edited by Bill Birkeland, 10-08-2003]
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Bill Birkeland Member (Idle past 2561 days) Posts: 165 From: Louisiana Joined: |
NosyNED wrote
"UH, what are the issues? Are these them: 1) What is the flood model for glaciation? 2) Snow depth over some aircraft? If so:1) I don't know where this is. 2) Done with, gone as an issue." In case of item 1, the flood model for glaciation, Young Earth creationists have an extreme problem in that their model postulates a single glacial episode. However, geologists, who have studied glacial deposits in detail, have found an abundance of evidence that demonstrates there have been multiple glaciations, 10 to 12. This evidence is summarized by books such as Sibrava et al. (1986). The glacial sediments directly deposited by glaciers and ice sheets are called glacial tills or, for short, "till". These glacial episodes were each separated by periods of time long enough for the deep weathering of the previous glacial tills; formation of well-developed soils, called "paleosols" when buried, in the tills; and the erosion of valleys in the glacial tills. For example, In Iowa, a person can find the following sequence of glacial - interglacial deposits as summarized in Chart 1 of Sibrava et al. (1986). (NOTE: Loess is a wind-blown sediments created during glacial episodes. During nonglacial times, loess deposition ceased and a soil formed in it as the result of weathering.) 1. Alden Member, Dowes formation (glacial till)2. "Wisconsin" loess 3. basal loess paleosol 4. "basal Wisconsin" loess 5. nonglacial sediments 6. "Yarmouth-Sangamon" paleosol 7. Hickory Till Member, Wolf Creek Formation 8. Dysart Paleosol 9. Aurora Till Member, Wolf Creek Formation 10. Franklin Paleosol 11. Winthrop Till Member, Wolf Creek Formation 12. Westburg Paleosol and Bishop volcanic ash bed 13. Alburnett Formation (multiple unnamed glacial tills) This is a sequence of glacial sediments, either loess or (glacial) till separated by either nonglacial deposits of river or streams deposits or a lengthy period of the nondeposition of glacial during which a soil was developed in the glacial tills of the previous glaciation. The character of the soils developed in the glacial tills and the fossil plants and animals that are found in the sediments associated with them indicate that the climate was much warmer than when the ice sheets deposited tills over Iowa. In Nebraska, the glacial tills of the Alburnett Formation, as found above in Iowa, overlies even older glacial tills. As summarized by Sibrava et al. (1986), the following sequence is found. 1. Peoria Loess2. Gilman Canyon Paleosol 3. Gilman Canyon Formation (loess and paleosols) 4. "Sangamon" paleosol complex 5. Loveland loess (subdivided by two paleosols) 6. "Yarmouth" paleosol with "Pearlette O" volcanic ash 7. Aurora Till Member, Wolf Creek Formation 8. Franklin Paleosol 9. Winthrop Till Member, Wolf Creek Formation 10. Westburg Paleosol and Bishop volcanic ash bed 11. Alburnett Formation (multiple unnamed glacial tills) 12. unnamed paleosol 13. "B" tills 14. unnamed paleosol 15. eolian and fluvial deposits with numerous paleosols and "Pearlette S and B" volcanic ashes. 16. paleosol 17. Elk Creek tills / "C" tills. In Illinois, a person finds this sequence 1. Peoria Loess2. Wedron Formation - numerous glacial tills 3. Farmdale paleosol 4. Winnebago Formation - numerous glacial tills 5. Sangamon Soil 6. Rador and Hulick Till Members of the Glasford Formation 7. Pike Paleosol 8. Kellerville Till Member of the Glasford Formation 9. Yarmouth Paleosol 10. Upper Banner Formation - multiple glacial tills 11. unnamed paleosol 12. Lower Banner formation - multiple glacial tills 13. West Lebanon Till As illustrated above, the various glacial tills are separated by well-developed "fossil" / buried soils, called "paleosols" when buried. The repetition of tills separated by paleosols clearly demonstrate that was not one glaciation, but multiple alternating periods of the formation of extensive ice sheets followed by either the extensive shrinkage or complete disappearance of these ice sheets from North America, Europe, and elsewhere. During extended period of glaciation during cold glacial climates the glacial tills and wind-blown silt called, loess, accumulated. During the interglacial periods, the accumulation of glacial tills and loesses ceased when the ice sheets melted away and these glacial deposits were weathered to create well-defined soils, called "paleosols", after being buried by younger glacial deposits. Tills were also eroded to form valleys in which alluvial sediment accumulated. Both were then buried by glacial tills deposited by ice sheets of the next glaciation. The laterally consistent alternation of paleosols and nonglacial deposits with glacial tills in the United States and elsewhere in the world clearly refute idea that the Ice Age was a single, short episode of glaciation. Also, the degree of weathering and soil (paleosol) formation that occurred between the deposition of individual sets of glacial till demonstrates that the period of time between the deposition of individual glacial tills was on the order of a 1,000 to 10,000 years depending on the specific soil. In their glacial model, Young Earth creationists ignore this and many other types of evidence that has been documented in innumerable published papers. Some papers that can be downloaded from on-line can be found at: Page not found - IIHRHydroscience & Engineering Hallberg, G. R., ed., 1980a, Pleistocenestratigraphy in east-central Iowa. Technical Information Series. no. 10. Iowa Geological Survey Bureau, Ames, IA. Page not found - IIHRHydroscience & Engineering Hallberg, G. R., ed., 1980b, Illinoian andPre-Illinoian stratigraphy of southeast Iowa and adjacent Illinois. Technical information Series. no. 11. Iowa Geological Survey Bureau, Ames, IA. Page not found - IIHRHydroscience & Engineering Hallberg, G. R., T. E. Fenton, T. J.Kemmis, and G. A. Miller, 1980, Yarmouth Revisited: Midwest Friends of the Pleistocene 27th Field Conference. Guidebook no. 3. Iowa Geological Survey Bureau, Ames, IA. Page not found - IIHRHydroscience & Engineering Kemmis, T. J., E. A. Bettis III, and G. R.Hallberg, 1992, Quaternary geology of Conklin Quarry. . Guidebook no. 13. Iowa Geological Survey Bureau, Ames, IA. Page not found - IIHRHydroscience & Engineering References Cited: Sibrava, V., D. Q. Bowen, and G. M. Richmond. (1986)Quaternary Glaciations in the Northern Hemisphere. Quaternary Science Reviews. vol. 5, Pergamnon Press, New York. 510 pp. There are just a few of seemingly innumerable papers that document the evidence for multiple, lenghty Ice Ages. NOTE: Most of this article was compiled from some USENET posts and was verified for accuracy. Yours, Bill BirkelandTexas
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Bill Birkeland Member (Idle past 2561 days) Posts: 165 From: Louisiana Joined: |
In Message 25 of 28 on
10-18-2003 10:55 AM, David wrote: "I was fortunate to have heard a lectureon this very topic a few weeks ago." Whether you were "fortunate" depends on whether the speaker knew anything about was he was talking about. There are a number of Young Earth creationists speakers out there, i.e. Kent Hovind, Carl Baugh, Don Patton, to name a couple, who are functionally illiterate in understanding what they are talking about. They sound authoritative, but instead know nothing about what they are talking. For example, go read: 1. Analysis of Kent Hovindhttp://www.geocities.com/kenthovind/ 2. Kent Hovind FAQs Examining "Dr. Dino"Kent Hovind FAQs: Examining "Dr. Dino" 3. What About Carl Baugh?A Commentary by Answers in Genesis http://members.aol.com/paluxy2/whatbau.htm 4. The Carl Baugh PageAccount Suspended Not all speakers know what they are talking about. David then asked: "It's easy to postulate that precipitationin one area has been the same throughout time, equal to what it is today. However, doesn't the existence on one or more ice ages negate that possibility?" It is true that there will be some variation in accumulation rates through time. However, the variations in accumulation can be determined by the various ways of independently dating ice cores. For example, volcanic ash particles from volcanic eruptions known to have occurred in AD 1783 and AD 79 have been found ice cores in central Greenland. These volcanic ashes and other markers provide datum by which variations in accumulation rates over time can be detected and such assumptions either validated or corrected. As previously noted in another post this is discussed in "The Two-Mile Time Machine" by R. B. Alley. Also, read "Ice Core Dating by Matt Brinkman" at:http://www.talkorigins.org/faqs/icecores.html David then stated: "We presently don't have the conditions tocreate an ice age of the proportions evidenced by geological evidence of giant boulders, and scratching of even some of the hardest rocks." That is why we are in an relatively "ice-free" interglacial stage instead of being in an full glacial epoch. If current conditions were the same as they were during the last glacial stage, the world be cold as heck and there would be continental ice sheets. This argument invokes an unrealistic hyper-uniformitarism, which infers that past environments must have observable modern analogues. However, the overall middle to late Tertiary global climatic cooling, orbital parameters, possibly even cycles in concentrations of interstellar dust, and other factors are present, which would have created another ice age had man-made factors not induced an artificial global warming. David then stated: "Large grooves were seen in one volcanotrunk. Only one of these grooves was broken by a successive freezing of water inside. If any ice age was very long ago, the rest of those grooves would've been broken." Where is the evidence that these glacial grooves were created by continental glaciation associated with the last glacial stage? Many mountains have alpine (mountain) glaciers that persisted after the end of the last glacial stage. In fact some of these alpine glaciers advanced significance distances downslope at times well after the last glacial stage and even in historic times. These grooves being discussed could very well be of recent origin. In fact, they might have under ice since the beginning of the last glacial stage and now being exposed by rapid melting due to global warming. Some web pages: 1. Reyes, A., and Smith, D. J., 2001, Tree-ring datesfor Neoglacial Lake Alsek, Yukon Territory, Canada. Canadian Quaternary Association/ Association canadienne pour l'etude du Quaternaire, Annual Meeting 2001. Whitehorse, Yukon Territory, August 20 - 24, 2001. at: http://cgrg.geog.uvic.ca/abstracts/ReyesTree-ringLake.html "Lake Alsek in southwestern Yukon Territoryformed several times during the Neoglacial when Lowell Glacier advanced across the Alsek Valley and blocked southerly drainage of the Alsek River.... The last major lake phase ended sometime between 1857 and 1891 and was preceded by a ponding event that ended between 1788 and 1832. An earlier, more extensive lake phase ended sometime after 1611. These results suggest that Lowell Glacier reached its maximum Little Ice Age position at least 200 years earlier than several other large valley glaciers in the northeastern St. Elias Mountains." The last major advance of this glacier was in 1857 and 1891 with another period of advance between 1788 and 1832. 2. REYES, Alberto V. nad others, 2003, TREE-RINGDATING OF LITTLE ICE AGE GLACIER ADVANCES AND ASSOCIATED ICE-DAMMED LAKES IN KLUANE NATIONAL PARK AND RESERVE, YUKON TERRITORY, CANADA. Session No. 52, Glaciers, Glacial Geology, and Glacial Ecosystems in the National Parks 2003 Geological Society of America (Seattle) Annual Meeting (November 2-5, 2003) at: http://gsa.confex.com/...3AM/finalprogram/abstract_67695.htm "The ages of seven such stems, which wedated by comparing their ring-width patterns to a ~900 year tree-ring chronology from nearby south Kluane Lake, suggest that Kaskawulsh Glacier was at its most extensive Holocene position in the early-mid 18th century." 3. A Service of The Greening Earth SocietyLittle Ice Age a Global Event by Diane Douglas Dalziel, Office of Climatology, Arizona State University at: http://www.greeningearthsociety.org/...cles/2001/hockey1.htm David also stated: "Isn't assuming there was only onefreezing and melting per year in a glaciation area reaching a bit? A storm followed by a melt would produce one layer. Ice has been seen melting in Antartica at 14F." Given what is known about the climate of where the ice cores were taken, it is not reaching it a bit. Contrary to what the lecturer was apparently stating, I seriously doubt there is going to be a spring thaw in the middle of winter in the middle of northern Greenland. In the part of Greenland in which the ice cores came, they don't have "storms" in the sense that the lecturer apparently was talking about. All this lecturer was demonstrating was a lack of knowledge about the climatology of Greenland. As far as ice melting at 14F, that temperature is -10C, which is a balmy July day for Greenland. What is unusual about ice melting in the summer? An informal article about Greenland in the summer is "Unraveling Climate's Mysteries atop an Arctic Summit A visit to Greenland, where scientists at a polar lab focus on the ozone hole above and the ice below" at: Bloomberg - Are you a robot?Bloomberg - Are you a robot? Also, the layering in ice coring are defined by much more than simply a melting and freezing. Then David commented: "We can debate the precipitation inGreenland vs. other areas, but the fact remains that there was 75m of ice deposited in 46 years in Greenland. That's 5.35 ft/year." We are not debating the precipitation of Greenland versus precipitation in other areas, i.e. Antarctica. We are primarily discussing the variation of precipitation **within** Greenland. It has been well documented that precipitation rates vary drastically **within** Greenland from over 5.4 ft/year (1.64 meters/year) along the southeast coast where the Lost Squadron crashed to less than 0.8 ft/year (0.25 m/year) at the GISP2 ice core site. The rate of accumulation at the Lost Squadron location is 625 percent that of the rate of accumulation at GISP2 ice core site. Given this difference, a person can't compare the depth of burial of the Lost Squadron with the accumulation of ice at the GISP2 site. It is like trying estimate how long it would take rainfall to fill up a newly dug pond in Lubbock, Texas using the rainfall rates for New Orleans, Louisiana Anyway, these variations are discussed and illustrated in: 1. Bales et al. (2001a) snow accumulation map for Greenlandhttp://www-bprc.mps.ohio-state.edu/...racts/BALESGRLFIG5.jpg 2. Bales et al. (2001b) snow accumulation map for Greenlandhttp://www-bprc.mps.ohio-state.edu/...bstracts/BALESFIG3.jpg 3. Bales, R. C., McConnell, J. R., Mosley-Thompson, E., and Csatho, B., 2001a, Accumulation over the Greenland ice sheet from historical and recent records. Journal of Geophysical Research (Atmospheres). vol. 106(D24), no.33, pp.813-33,825. http://www-bprc.mps.ohio-state.edu/...tracts/bales-jgr-1.pdf 4. Bales, R. C., McConnell, J. R., Mosley-Thompson, E., and Lamorey, G., 2001b. Accumulation map for the Greenland ice sheet 1971-1990. Geophysical Research Letters, 28(15), 2967-2970 http://www-bprc.mps.ohio-state.edu/...s/Bales2001GRL-Aug.pdf 5. PDF files of publications on Green land climatologyhttp://www-bprc.mps.ohio-state.edu/...stracts/Abstracts.html 6. Snow Accumulation at GISP2 Summit, GreenlandPage not found - The University of Maine David commented: "In an ice age, wouldn't you thinkyou could build up alot more ice?" Yes, but doubling the rate from 0.25 meter/year to 0.50 meter/year wouldn't even begin to match the rate of accumulation at the Lost Squadron location. Climatic change doesn't operate in a nice linear fashion. Just because an ice age occurs doesn't mean that that there would be any large increase in accumulation rates. In fact, it is possible that in some parts of Greenland that glacial accumulation rates would be less than modern accumulation rates. Given the complex manner in how oceanic and atmospheric circulation patterns and associated precipitation patterns would differ from modern circulation and precipitation patterns, a person can't predict whether the glacial precipitation would either less or more than modern precipitation and by how much at any specific point by using only intution. A person would have to carefully model these changes using as much paleoenvironmental data they can get collect to answer this question for a specific location such as the GISP2 location. Finally, David commented:" A global flood, combined with extremevolcanism (blocking out the sun's rays) and mass evaporation after the flood, could have resulted in an ice age lasting about 700 years. Ocean volcanism would've resulted in warmer oceans, increasing precipitation." The problem here is that there is neither the evidence of a global flood nor extreme volcanism having occurred just before the ice age. Enough deep sea cores have been collected from all around the world by the Deep Sea Drilling and Ocean Drilling projects to disprove the notion that anything above normal volcanism occurred during the last or any other glacial epoch. Finally, using foraminifer assemblages and oxygen isotope analysis of those foraminifer from deep sea cores, it is well known that during the glacial stages, sea weren't warmer as proposed above. In fact, they were either cooler or somewhat cooler during the glacial stages than they are now. For example: CLIMAP Last Glacial Maximum August Sea Surface Temperatures at:views: CLIMAP LGM aug sst data: CLIMAP LGM aug sst CLIMAP Modern August Sea Surface Temperatures at:views: CLIMAP MOD aug sst data: CLIMAP MOD aug sst Some examples are: 1. Pflaumann, U., et al., 2000, Glacial NorthAtlantic: Sea-surface conditions reconstructed by GLAMAP. Paleoceanography. vol. 18, no. 3, pp. 1065-1072. at: http://www.agu.org/pubs/crossref/2003/2002PA000774.shtml 2. Sachs, J. P., Anderson, B. F., Lehman, S. J.,2001, Glacial surface temperatures of the southeast Atlantic Ocean. Science. vol. 293, pp. 2077-2079. Page Not Found | MIT - Massachusetts Institute of Technology 3. Trend-Staid, M., and Prell, W. L., 2002,Sea surface temperature at the Last Glacial Maximum: A reconstruction using the modern analog technique, Paleoceanography. vol. 17, no. 4, pp. 1065-1069. http://www.agu.org/pubs/crossref/2002/2000PA000506.shtml "One of the most important results is the2-6C mean annual cooling in the central to eastern tropical Atlantic and up 8C cooling in the eastern tropical Pacific." Finally, almost any of the paleosols lying between sets of glacial tills, which I mentioned in my previous post, certainly took longer than 700 years to form. They alone certainly demonstrate that the Pleistocene Ice Ages, even the last glacial stage, lasted more than 700 years. Yours, Bill BirkelandTexas.
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Bill Birkeland Member (Idle past 2561 days) Posts: 165 From: Louisiana Joined: |
Lizard Breath asked;
"item I've seen in Southern Canadaand the Plains States is an abundance of fertile top soil that's exploited by farmers. I might not be incorporating all of the dynamics of glacier flows, but from what I've read in these posts and their associated URL's, 10 to 12 glacier episodes along with countless minor flux's should have transported the top soil into the oceans or at least left most everything North of 41 degrees unsuable for agriculture..." The areas being farmed that Lizard Breathe talks about are where the retreating ice sheets of the youngest glacial advance dumped sediment eroded from further north in the Canadian Shield as glacial tills. Also, large parts of this area were once covered by large proglacial lakes, i.e. Lake Agassiz, in which huge amounts of sediments accumulated in front of the northward retreating ice sheets. In these areas, the fertile topsoil that is exploited by farmers was formed by the weathering of these glacial tills and large proglacial lake deposits, which were deposited as the ice sheets of the last glaciation retreated. Older soils were indeed either buried or eroded away. It just that the topsoils noted by lizard Breathe were created by about 7,000 to 10,000 years of weathering after last ice sheet retreated. Since they are younger than any of the glaciations, the glaciations couldn't have affected them. (NOTE: If the glacial deposits were as young as Young earth creationists argue they, the fertile topsoil that Lizard Breath talks about, wouldn't have had time to form.) As a person looks further north, the glacial deposits do become thinner and eventually the landscape was scoured down to bedrock and is virtually useless for agriculture. Large parts of the Canadian Shield have been scoured down to bedrock. Even if northern Canada was warm enough to support agricultural, it would be useless for farming there because of the shallow depth to bedrock or bare rock at the surface. One major farming region lies on the weathered lake plain of Lake Agassiz. Page Not Found - Removed | University of North Dakota
Page Not Found - Removed | University of North Dakota http://www.winona.msus.edu/geology/MRW/text/text96-121.html Lizard Breath Then asked: "and created "super deposits"of top soil threads in the central and southern latitudes of the United states." The thickness of topsoil is only about 1 to 1.5 meters (3 to 5 ft). When this thin layer was eroded, it was mixed into the tremendous amount of non-topsoil material as the ice sheet eroded deeper into the ground beneath. The ice sheets mixed this material instead of nicely separating the material they eroded into topsoil and non-topsoil material. As a result, the topsoil is there, but it is completely mixed with and utterly diluted by non-topsoil sediments to the point that it impossible to recognize it unless a person happens to find a cobble-size clast of it within the till. Glacial processeshas dispersed the topsoil throughout glacial tills. Also, the topsoil has been reworked and spread throughout glacial outwash that fills large parts of the Mississippi river Valley; deposited offshore as deltas and in the Mississippi deep sea fan which covers a large part of the bottom of the Gulf of Mexico; and spread about the landscape as wind-blown silt called "loess". The loess has been blown out of the Mississippi River Valley and blankets the landscape on either side of it. No "super deposits" of topsoil exist because older topsoil has been mixed into unweathered bedrock eroded along with the topsoil and either dispersed across the modern landscape as loess; buried within the Mississippi Alluvial Valley; or now submerged beneath the Gulf of Mexico as part of submerged delta or submarine fan systems. Lizard Breath Then asked: "The most fertile top soil area in theUnited States other than the San Juaquin Valley is the area south of the Great Lakes running from as far east as Buffalo NY to central Iowa. Even then, the depth of the top soil is not indicative of mass deposits although the location of the most fertile area does coincide with the average leading edge termination point of the glacier sheets." A lot of this area is covered by loess, wind-blown silt, which was blown either out of the Mississippi River Valley or from Pleistocene age dune fields in the Sand Hill region in Nebraska and adjacent areas. The soils are fertile, in part, because they are only several thousand years old and the sediment, in which they are developed, hasn't been completely leached of their nutrients by weathering and soil processes. A good loess reference: E. Arthur Bettis, III , Daniel R. Muhs,Helen M. Roberts and Ann G. Wintle, 2003, Last Glacial loess in the conterminous USA, Quaternary Science Reviews. Vol. 22, No. 18-19, Pp. 1907-1946 (September 2003) Yours, Bill Birkeland
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Bill Birkeland Member (Idle past 2561 days) Posts: 165 From: Louisiana Joined: |
In Message 32, Lizard Breathe asked:
"I was also wondering why we don't seea deposit ridge or some type of smooth ridged mountain range running laterally across the United States corresponding to the termination point of the ice sheets similar to the heap that a Dozer leaves if it pushes material along and then does a sudden retreat backwards." Actually these ridges do exist and do extend laterally across most of the Untied States. They are called "end moraines" or "terminal moraines". The maps of glacial landforms for the Midwest and other parts of the United States clearly demonstrate that they do exist. For the Untied States, go look at: Soller, David R., and Patricia H., 1997,Map showing the thickness and character of Quaternary sediments in the glaciated United States east of the Rocky Mountains; northern and central plains states (90 degrees to 102 degrees west longitude). Miscellaneous Investigations Series. no. I-1970-C. U. S. Geological Survey, Reston, VA, United States and Soller, David R., and Patricia H., 1998,Digital representation of a map showing the thickness and character of Quaternary sediments in the glaciated United States east of the Rocky Mountains. Digital Data Series no. DDS-0038, U. S. Geological Survey : Reston, VA, United States. Similar end moraines are found in Eurasia and elsewhere in the world. For an on-line example, the distribution of end moraines, colored in brown, can be seen in:
http://go.owu.edu/~jbkrygie/krygier_html... This figure is part of:http://go.owu.edu/...geog_111/geog_111_lo/geog_111_lo14.html Other end moraines can be seen mapped as dark green arcuate features in:Page not found – Illinois Natural History Survey and
http://www.museum.state.il.us/RiverWeb/landings/... However, glaciers did not bulldoze either rock or sediment in front of them. Rather they erode this material at their bases; transport it "downstream"; and dump the sediment at their terminus where they melt. Glaciers are conveyor belts, not bulldozers. How this process works are illustrated at: The origin of terminal moraines is illustrated in "DEPOSITIONAL PROCESSES" at:http://www.homepage.montana.edu/~geol445/hyperglac/depproc1/ 1. "Glacial Landforms" at:http://jove.geol.niu.edu/...9_info/429trips/NIF/Glaciers.htm and figures at:http://jove.geol.niu.edu/.../NIF/Glaciers_files/image006.gif http://jove.geol.niu.edu/.../NIF/Glaciers_files/image008.gif 2. End Moraines-the End of the Glacial Ridehttp://www.isgs.uiuc.edu/...geobits-pub/geobit2/geobit2.html 3. figure 3 at:http://www.homepage.montana.edu/...glac/depproc1/moraine.JPG "Figure 3 compares a glacier with a conveyerbelt. This shows how material that gets put into transport is carried by a glacier to it's terminus. Debris gets deposited at a glaciers terminus by melt out of the slow moving ice. Debris can also be "rafted" on top of a glacier to it's terminus where it gets deposited. Debris rich ice can become separated from a glacier and become incorporated in a terminal moraine." 4. Also, it is illustrated at;http://craton.geol.brocku.ca/...1F90/glaciers/figure152.html 5.Finally discussed in "Sedimentary environments of terrestial end moraines" at:http://www.inqua.au.dk/cog/sed-env.html 6. Depositional Landforms Moraineshttp://www.geology.iupui.edu/...powerpoints/deposition_1.ppt Yours, Bill Birkeland {Shortened display form of 2 URLs, to restore page width to normal - Adminnemooseus} [This message has been edited by Adminnemooseus, 12-23-2003]
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Bill Birkeland Member (Idle past 2561 days) Posts: 165 From: Louisiana Joined: |
I posted this in the wrong place. My mistake.
[This message has been edited by Bill Birkeland, 04-08-2004]
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Bill Birkeland Member (Idle past 2561 days) Posts: 165 From: Louisiana Joined: |
AbbyLeever wrote:
"Reference I used to have online for Kitigawa et al on the lake varves {is \ was}http://www.cio.phys.rug.nl/HTML-docs/Verslag/97/PE-04.htm but it seems to be down now." For the time being, a PDF copy of Kitagawa's research can obtained by clicking the below citation. H. Kitagawa and J. van der Plicht, 1998, AtmosphericRadiocarbon Calibration to 45,000 yr B.P.: Late Glacial Fluctuations and Cosmogenic Isotope Production. Science. vol. 279, pp. 1187-1190 (20 February 1998) I suspect that the PDF file of his article is posted at this link only on a temporary basis. Thus, if a person wants a copy they should download it sooner than later. A couple of related articles available online as PDF files are: 1. Towards an Absolute Chronology of the Last Glacial byOlaf Joris and Berhard Weninger at: Seite nicht gefunden – MONREPOS 2. Yours Bill Birkeland
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