06. Deglaciation
CHAPTER 6
Deglaciation
According to the model presented in this book, when the average ocean temperature cooled to 10°C, less oceanic evaporation occurred, fewer clouds were present at higher latitudes, more radiation penetrated to the surface, and most ice sheets began to melt. The mid and high-latitude winter climate would continue to cool, until it became colder than it is today. Summers would become warmer, but still cooler than at present. Storms would become drier and windier, while rivers would be gorged with meltwater and sediment. Drastic ecological changes would stress plants and animals. Some animals would become extinct, while others would be forced equatorward. At this time, the woolly mammoth most likely became trapped in Siberia and Alaska, where it was unable to survive. In this chapter, we will discuss, in more detail, the changes that took place during deglaciation. We will first examine the climate to see what would cause further mid-latitude cooling. Then, we will calculate the time required to melt the ice sheets in the Northern Hemisphere. The water from the melting ice sheets would produce significant changes in the river valleys. We will conclude with reasons for the extinction of many ice age megafauna, with special focus on the woolly mammoth in Siberia and Alaska. The Big Chill
What would cause the winters to cool during deglaciation? At glacial maximum, the relatively warm ocean (10°C) would still cause a somewhat mild climate. Although volcanism was probably very low, and sunshine more intense than during ice buildup, the presence of the ice sheets would continue generating cold continental air. This air, spreading out over the higher latitude ocean, would cause further cooling of the deep ocean. Eventually, the deep-ocean temperature would reach the current average of 4°C. At the same time, the mid and high-latitude atmosphere, during winter, would gradually cool, because of the presence of the ice sheets and because of diminishing heat and moisture added to the air due to the cooling ocean. The ocean and atmosphere would likely cool below today’s average, as long as a substantial proportion of the ice sheets remained.
Climate simulations, initialized for maximum ice-age conditions, have regularly demonstrated a drastically colder climate. Kutzbach and Wright (1985) found at least a 10°C drop in winter temperature, and about a 30°C cooling in summer over the ice sheets, compared with the present. The drop in temperature south of the ice sheets in summer was less than 10°C, the difference decreasing with distance from the ice sheets. Their model has major deficiencies and large differences from the model presented in this book. Kutzbach and Wright used the assumed one-to-three kilometer high elevation of past ice sheets, and a yearly albedo of 0.8. Each of these values is much too high. Manabe and Broccoli (1985b), using uniformitarian ice-age boundary conditions-except for the sea-surface temperature which their model predicted, rather than assumed-found much the same summer temperature distribution as Kutzbach and Wright had. However, summer temperatures warmed more rapidly with distance south of the ice sheets in Manabe and Broccoli’s simulation than they did in Kutzbach and Wright’s treatment. These models generate too much cool air, but they nevertheless indicate the chilling effect of an ice sheet. As the post-Flood climate cooled, the Arctic Ocean would eventually freeze over. Sea ice would spread over the northern North Atlantic and North Pacific Oceans, becoming more extensive than in modern winters. These changes would occur hand in hand with the atmospheric cooling, reinforcing each other. This strong cooling may explain why the Arctic Ocean is frozen today. Some investigators believe that if the Arctic Ocean suddenly became ice free, it would not refreeze (Fletcher, 1968, pp. 98, 99). Evidently, a significantly colder climate than we experience at present must have caused the Arctic Ocean to freeze over for the first time.
There are two reasons why the present climate would have difficulty freezing the surface of the Arctic Ocean. First, an ice-free Arctic Ocean warms the air substantially (Newson, 1973). A much warmer atmosphere would cause more heat absorption by the water, making it more difficult to cool, in winter. Second, it is difficult to freeze sea water. When the salinity is higher than 24.8 parts per 1,000, the density of the water continues to increase as the temperature falls below 4°C. This is just the opposite of fresh water. The salinity of sea water is around 36 parts per 1,000, and does not vary significantly in the ocean surface layer. Consequently, when the surface cools in winter, the water will continually sink and be replaced by slightly warmer water from below. The surface would freeze only when the surface salinity is sufficiently lowered, by the addition of less-dense, fresh water, and/or cold surface temperatures extend by mixing to considerable depths (Stewart, 1978). Once sea ice forms, it will cool the air above and reinforce the conditions for its survival. Although their climate simulations are exaggerated, both Kutzbach and Wright. (1985), and Manabe and Broccoli (1985b), show that sea ice, in the North Atlantic, would cool the winter atmosphere above the ice, 30 to 40°C below current values.
Since the atmosphere late in the ice age would be significantly colder than it is at present, the average ocean temperature probably would cool a little below the present average of 4°C, before the ice sheets completely melted. The change in the average temperature of the ocean, following the Flood, is depicted in Figure 6.1.
Graph of the average temperature of the ocean following the Flood. The average ocean temperature cools below today’s average as the ice age glaciers melted because the atmospheric temperature at higher latitudes is much below the present.
While the ocean and atmosphere cooled, the atmosphere eventually would become even drier than it is now. The drying trend would be mostly a result of the reduced ability of colder air to hold moisture (Figure 1.2), together with less evaporation from the cooler ocean. Models have consistently indicated less precipitation over the continents under such circumstances (Kutzbach and Wright, 1985, p. 147). Sunshine probably would be greater, although non-precipitating low clouds may have increased, due to the chill from the ice sheets. A strong anticyclone (high pressure) with katabatic winds (outflowing downglacier winds) would frequently blow off the ice sheet margins (Kutzbach and Wright, 1985, pp. 154-156). The air above the ice sheets would be replaced, from high levels in the atmosphere. This process would further dry the air, over and near the ice sheets.
Although the tropics would cool slightly during the ice age, once ice-age volcanism diminished, the lower latitudes would recover more rapidly than mid and high latitudes. This would make the hemispheric north-south temperature difference during deglaciation greater than it is today, with the greatest gradient near the periphery of the ice sheets. Consequently, the jet stream would be more intense, and the storm tracks would average further south (see the discussion of the thermal wind equation in Chapter 3). The average major and minor storm tracks, as well as areas covered by ice sheets and sea ice midway through deglaciation, are illustrated in Figure 6.2. These changes in the storm tracks and the jet stream have been modeled on a theoretically consistent basis (Kutzbach and Wright, 1985; Manabe and Broccoli, 1985b, pp. 2174-2178).
Distribution of snow and ice and main storm tracks about midway through deglaciation. Notation the same as in Figure 3.6. Sea ice coverage represented by slanting lines. Southerly main storm track caused by colder climate than at present.
Although the climate at mid and high latitudes would be drier, on the average-especially over and south of the Northern Hemisphere ice sheets-some areas close to the southern main storm tracks likely would be wetter than they are now. So, during deglaciation, some regions between about 20 and 40°N would have been favored with more precipitation than they are in the current climate. But this would not prevent the pluvial lakes in this latitude belt from drying. According to recent calculations, Lake Bonneville would have needed six times the precipitation in its drainage basin, to maintain its maximum level. Even if precipitation was twice the present value and the temperature was significantly cooler, Lake Bonneville would shrink during deglaciation. As a result of the storm track located just south of the ice sheets in the Northern Hemisphere (Figure 6.2), stronger storms than those which develop today would tend to track parallel to the southern periphery. The storms over continental areas south of the ice sheets would be characterized by strong winds and relatively low precipitation. Blowing sand and dust would be a frequent occurrence, especially in the dry season. This feature is likely the reason for the extensive ice-age sand dunes, like the Nebraska sand dunes, and the loess sheets found south of the former ice sheets and sometimes intermingled with glacial till near the periphery. At one time, there was uncertainty as to whether or not loess was a wind-blown deposit. It is now considered to be wind blown (Smalley, 1975; Pye, 1987, pp. 199-265). Loess is found over much of the midwestern United States, and is especially thick in, and eastward of, major river valleys, such as the Mississippi River valley (Ruhe, 1983). Loess is also found over much of central Europe, and eastward into the Soviet Union and China (Flint, 1971, pp. 251-266). Wind-blown dust is also extensive in the lower sections of Greenland ice cores, which, presumably, represent late glacial time (Bradley, 1985, pp. 165-166).
Rapid Melting of Ice Sheets Would the ice sheets melt during the big chill? The answer is a resounding yes; and the required time is surprisingly short. The most scientific approach, to determine the time required for melting of the ice sheets, is by use of the energy balance equation to estimate ablation rates (Hay and Fitzharris, 1988, p. 145). This approach has been attempted only within the past decade or two (Pollard, 1980, p. 384). Lack of acquaintance with it is probably the principal reason why long-age estimates for deglaciation continue to be proposed. The big chill would produce much colder temperatures in winter, but summers would be warmer than during the buildup of the ice sheets, although cooler than in the modern climate. Winter snowfall would be light, so that most of the summer sunshine and heat would be available to melt the ice sheets. In calculating an average melting rate during deglaciation, we may assume no ablation by icebergs calving into the ocean or into extensive proglacial lakes. We may also assume no sublimation, which is evaporation, without passing through the liquid state. These can be significant effects in local areas of the ice sheet. Neglecting the above effects will result in a conservatively low ablation rate. Disregarding geothermal heat and the transfer of heat from the air to the snow by molecular conduction, each of which is a relatively small contribution, the energy balance equation is (Paterson, 1981, pp. 299-320):
QI + QM = FR + FE + FC + FP(6.1) in which QI is the heat gain in a vertical column of ice from the surface to a depth at which vertical conduction is negligible; QM is the heat used for melting; FE is the difference between solar and net infrared radiation; FC is the heat gained by condensation onto the snow surface; FC is the heat added to the surface due to warmer turbulent air; and FP is the heat added by rain. All quantities in Equation 6.1 are expressed in amount of energy per unit area, per unit time, i.e., as rates per unit area. FP is significant and positive, if the rain can freeze, but generally is small, and will be neglected in the dry post-maximum climate (Paterson, 1981, p. 301). The first three terms on the right are the same terms that enter into the heat-balance equations for the ocean and atmosphere. But over a snowcover, FE and FC are practically always positive during the melt season when the air temperature just above the snow is warmer than 0°C and the water vapor pressure is greater than the saturation vapor pressure at 0°C. QI is the heat needed to raise the temperature to 0°C, so that the ice can melt. Since the specific heat of ice is about one-half that of water, the temperature of the ice can be raised rather quickly, up to freezing, early in the melt season. QM can be negative, if meltwater refreezes, but this will mainly occur only at the beginning of the melt season, and will greatly aid the warming, or “priming,” of the ice sheet. This is because the freezing of one gram of meltwater will raise 160 grams of snow or ice one degree Celsius (Paterson, 1981, p. 311).
According to these considerations, during the remainder of the melt season after the ice sheet has been primed, Equation 6.1 becomes:
QM = FR + FE + FC(6.2) The details of the solution for QM, during deglaciation, are given in Appendix 3. From a comparison with modern glaciers, FR normally accounts for 60% of the ablation, and FE and FC, about %. Therefore, the latter two terms can be eliminated by adding .67FR so that ablation is simply expressed in terms of the radiation balance.
Central Michigan was chosen as the location at which to calculate the melting rate for the periphery of the ice sheet. Although the ice sheet would have begun melting when oceanic and atmospheric temperatures were relatively mild, the average deglaciation temperature for central Michigan was assumed to be 10°C colder than the current warm season average. The ablation season was assumed to begin May 1, after the winter snow melted, and the ice sheet primed, and to end September 30. Since the melting of one cubic centimeter of ice requires a specific amount of heat energy (80 calories), the terms in Equation 6.2 can be expressed as meters of ice melted per year, rather than energy units per square centimeter per year. The radiation balance depends, partially, on the average cloudiness and albedo. For these effects, maximum and minimum values were determined. From a range in cloudiness and albedo, QM varied from 7.2 to 17.7 meters/year. The best average melting rate is estimated to be 10.4 meters/year. From the range of ice depths calculated in Chapter 5, the periphery of the ice sheet would melt in 50 to 87 years-surprisingly short, compared to uniformitarian estimates. The interior of the ice sheets would melt more slowly, but probably within 200 years. Thus, the total length of time for a post-Flood ice age from beginning to end, is about 700 years. Figure 6.3 graphs the projected change in ice volume with time. After the ice sheets melted, ice volume would be less than today, because Antarctica and Greenland ice sheets would not have built yet to their current size.
Graph of world ice volume following the Flood. The volume of ice gradually increased after the ice age glaciers melted because Greenland and Antarctica ice sheets still were growing. The melting rate for a post-Flood ice age is considerably greater than given by uniformitarian estimates. The uniformitarian estimates are based on an expanded time scale, and not on physical principles. Up to the present, only one climate simulation (to this author’s knowledge), has attempted to physically calculate ice sheet ablation. In this model, ice-sheet topography was held constant, but a subprogram calculated the annual ice balance (Manabe and Broccoli, 1985b, pp. 2179-2181). According to Manabe and Broccoli’s Figure 20, the ice in a 400-kilometer-wide strip along the southern periphery of the Laurentide ice sheet, melts at about 3.5 meters/year This is in spite of the huge size of the ice sheet, and an unrealistically high constant albedo of 0.7 for the melt season. Manabe and Broccoli (1985b, p. 2180) state: “An extremely rapid depletion of ice occurs in a relatively narrow belt along the southern margin of both ice sheets.” Referring to this result at a conference on the astronomical theory of the ice age, Birchfield (1984, p. 857) states: “A new mass budget calculation for the Laurentide ice sheet by Manabe, produced very large melt rates, implying a long-term, ice-sheet retreat, far in excess of that observed.”
“Observed” in the above quotation means, “inferred according to the geological time scale,” in which one glaciation lasts 100,000 years. During this time, glaciation is rather slow, with very large retreats and advances, called interstadials and stadials, respectively, followed by a complete termination that occurs relatively fast in about 10,000 years (Broecker and Van Donk, 1970). An attitude, in which physical calculations, although crude, but, nevertheless, qualitatively sound, are rigidly subordinated to a geological time scale based on many assumptions, is unfortunate, but common. This is but one example of the reinforcement syndrome that keeps a model, or paradigm, intact, internally consistent, and impressive to laymen and scientists alike (Oard, 1985, pp. 178, 179). The results reported in this chapter are consistent with modern observations of temperate glaciers. Ancient glaciers, especially along the southern terminus, probably were similar to modern temperate glaciers. Sugden and John (1976, p. 39) state that glacier-melting can be rapid as indicated by “... many mountaineers whose tents in the ablation areas of glaciers may rest precariously on pedestals of ice after only a few days.” 12 meters/year is the average melting rate at the snout of some Norwegian, Icelandic, and Alaskan glaciers (Sugden and John, 1976, p. 39).
Even high-latitude glaciers have large ablation rates. As mentioned previously, the fastest moving glacier in the world, the Jakobshanvs Glacier, at about 70°N, has been measured to melt at 55 meters/year (Hughes, 1986). This is due to several positive-feedback mechanisms, and is unusual, but these positive feedbacks would be operative in some areas of the melting ice sheets. Beget (1987, p. 85) has found that current glaciers, about 70°N latitude in northeast Canada, melt at 5-7 meters/year at low elevations, and 1 1/2-3 meters/year at elevations of a kilometer. These modern observations indicate that the values estimated in this chapter and in Appendix 3 for ice-age glaciers, are indeed reasonable and conservative. Not all of the ice sheets would melt during the deglaciation epoch. The Antarctic and Greenland ice sheets would continue growing, even after the other continental ice sheets disappeared. This is because of the high latitude, relatively high altitude, and usually fresh snow surface of these ice sheets. At glacial maximum, the depth of ice on Antarctica averaged about 1,200 meters. East Antarctica would have received more than this amount, since it would have started the ice age mostly above sea level. West Antarctica, on the other hand, would have consisted of only mountain glaciers, during the early phase of the ice age. Since the ocean between mountain ice caps is rather deep in places-even considering glacial rebound-some time would be required before these mountain glaciers would be coalesced into the West Antarctic ice sheet. During early deglaciation, the ocean water would still be relatively warm. As the ocean temperature fell from 10°C to 4°C, snowfall would be significantly heavier than at present, and the ice sheet likely would grow a few hundred more meters. When the water temperature became cold, snowfall would have tapered off to the present slow rate. The current, average-water equivalent precipitation for Antarctica Isa 17:1-14 cm/yr. At the periphery, precipitation is higher, and in the interior, it is less than five cm/yr (Paterson, 1981, p. 56). At the 17 cm/yr rate, at least another 600 meters of ice would have accumulated on Antarctica since the end of the ice age, especially at the margins. These considerations indicate that a rapid ice age and the modern climate can account for the present depth of ice on Antarctica. A scenario, analogous to the one for West Antarctica, would have occurred on Greenland. Due to the proximity of the warm ocean, only mountain glaciers would have developed, at the beginning. During the later stages of the ice age, the mountain ice caps would merge into the Greenland ice sheet. Interior areas of Greenland may have accumulated more than the Northern Hemisphere ice-age average of 700 meters. A few hundred more meters of ice could have been added, during deglaciation. Currently, Greenland accumulates a yearly average of 15 cm of ice in the north, and more than 90 cm of ice in the south, with a yearly average of 30 cm of ice (Fristrup, 1966, p. 234). Since the end of the ice age, an additional 1,050 meters of ice could have accumulated on Greenland, in the present climate. From a uniformitarian point of view, it is difficult to account for these ice sheets (Loewe, 1971, p. 331; Anonymous, 1978, p. 25). Conditions may have been unfavorable for their beginning. Sugden and John (1976, p. 97) write: “It is often argued, for example, that if the ice were suddenly removed from Greenland and Antarctica, the climate would, perhaps, be too mild to nourish new ice sheets.” The high East Antarctica ice sheet is now a polar desert, receiving less than five centimeters of precipitation a year. How it grew to over three kilometers deep is a uniformitarian puzzle: “Exactly why... the Antarctic Ice Sheet grew to the dimensions it has today, is not yet known, however” (Anonymous, 1978, p. 25).
Alluvial Terraces and Underfit Streams
River valleys around the world are usually deeply filled with river sediment, or alluvium. Within these valleys, terraces, or steplike features, are cut in the alluvium, along each bank. Some terraces are high above the present-day river (Figure 6.4). Practically all river valleys show signs they were once filled by much larger rivers. The current rivers are, therefore, underfit. This is shown especially by the size of ancient river-meanders, but can also be deduced by the width of the valleys compared with the width of the present rivers. Both creationists and evolutionists have explanations for these observations (Whitcomb and Morris, 1961, pp. 318-324; Strahler, 1987, pp. 284-292). This section will supplement the creationist explanation with a post-Flood, ice-age model, and will address Strahlers’ criticisms.
Before discussing terraces and underfit streams, we must back up a bit, to the end of the Genesis Flood. As the land was rising to drain the Flood waters, tremendous erosion of soft, or loosely consolidated continental sediments occurred. This eroded material flowed towards and into the sea, through the river valleys. Where the river slope became fairly flat in its lower reaches, like the lower Mississippi River Valley, much of this sediment would be deposited in vast alluvial plains. At this time, large river deltas would have developed at the seacoast. As the ice age began, vast blankets of alluvium would already be in place, as observed in most river plains today. In other areas of the river courses, mainly in the central and upper reaches, wide valleys and large meanders would have been cut by the retreating flood waters. As the ice age developed, precipitation would have been at least three times greater than it is today. Over non-glaciated lands, this precipitation would have reinforced flood geomorphological features, and probably caused multiple terraces in the river valleys. Significant downcutting of the lower reaches of alluvial valleys may also have occurred. In glaciated areas, valleys cut by the draining waters of the Genesis Flood would be filled with glacial till, since these valleys would be natural traps for glacial debris.
While the ice sheets were melting rapidly, tremendous volumes of water would have been added to the rivers each summer. The amount of water would be very difficult to estimate, but 10 to 20 or more times the present flow would be likely. Immediately south of the melting ice sheets, the cold climate would have caused permafrost, which has left signs of its former existence. Water could not percolate below the permafrost in summer, and would run off, further adding to the volume of water carried by rivers.
Large fluctuations in river volume, mainly between winter and summer, would cause a complex pattern of terraces south of, and within, the glacial boundary. Sometimes the rivers would deposit sediments, while at other times, the rivers would cut through these sediments.
Schumm (1977, pp. 214-221) describes how variable numbers of terraces can form rapidly, due to episodic erosion and sedimentation in a stream that drains terrain of high relief. Douglas Creek, in Colorado, has formed one to seven discontinuous stream terraces, since 1882. The total downcutting has been about nine meters. The discontinuous nature of the terraces indicates a different erosional-depositional history at various points in the channel. Although Douglas Creek is not an exact analogy for rivers during the melting of the ice sheets, it does have implications for other streams and rivers with episodic high stream flow. Schumm (1977, p. 220) extends the observations to other areas, and summarizes: This suggests that perhaps the flight of terraces that form where large quantities of stored glacial and alluvial sediments are being removed from a valley are also the result of the complex response or episodic erosion mechanism... rather than a response to climatic fluctuations.... In other words, terraces can be formed by episodic erosion, and not just from climatic fluctuations. Within the context of the ice age, terraces could just as easily form by episodic flooding and erosion from the melting of the ice sheet, as from the long-period glacial/interglacial oscillations that are used by uniformitarian scientists to explain them. For instance, Gage (1970, p. 621) states:
Vertically spaced by tens of feet and underlain by tens of feet of gravel, such terraces in many parts of the world have been attributed to glacial-deglaciation cycles spanning thousands of years; yet similar features of the same magnitude are known to form, basically by the same processes, within a minute fraction of the time. A striking example was provided by the Waiho River, which drains the Franz Josef Glacier in New Zealand. During a single high-intensity rainstorm in December 1965, the riverbed was aggraded from 10 feet to about 80 feet over several miles, and in the succeeding few weeks rapid downcutting and channel shifting produced a flight of 10-foot terraces.... Colonized rapidly by plants in this moist temperate region, they soon acquire a false aspect of antiquity and in another environment might be mistaken for late Pleistocene degradational terraces.
River terraces can form rapidly by the rapid melting of the post-Flood ice sheets; and they may lay exposed for sufficient time to form a soil, and then be buried by another depositional event. Thus, paleosols, which are ancient soils, can sometimes be found associated with the top of terraces. Paleosol formation need not take a long period of time, as we will discuss in the next chapter. Glacial/interglacial oscillations may seem reasonable within the uniformitarian framework, but Baker (1983, pp. 118, 119) states that, because of the problems of separating climatic controls from other factors, terraces likely are unreliable for Quaternary chronology. Strahler (1987, p. 289) does recognize that creationists can explain river terraces by just the mechanism proposed above: “One possibility would be enormously increased precipitation; another would be extremely rapid melting of the glacial ice during deglaciations.” Because of his neo-uniformitarian presuppositions, he does not accept this explanation. However, given the initial conditions of a post-Flood ice age, with a warmer ocean, and the physics of snow and ice ablation, what Strahler believes impossible is very probable.
River valleys over most of the world show obvious signs of much larger runoff rates than occur today. This heavy runoff could be due to draining floodwater, higher post-Flood precipitation, or rapid melting of ice. Dury (1976, p. 220) describes most rivers as “manifestly underfit,” meaning very large differences between present and past flow. Many properties of present rivers, such as bankfull width, depth, slope, and meander geometry, are correlated to each other, and to river discharge. Equations relating these properties have been derived by many investigators (Dury, 1976; Williams, 1986, 1988). Unfortunately, most of these properties are difficult to extrapolate to paleorivers (Dury, 1976, pp. 221, 222). However, the wavelength of incised meanders has a high degree of significance, and can give a reasonable estimate of river discharge.
Dury has worked, for years, on relating meander wavelength to river discharge for both present and past rivers. In general, discharge rate increases with the square of the average meander wavelength (Dury, 1976, pp. 222-224; Williams, 1988, pp. 328-330). Dury has found that the average paleomeander in the United States is five times the meander of the current underfit stream or river (Baker, 1983, p. 120). Near the ice front in Wisconsin, the meanders are ten times larger. This implies an average discharge 25 times greater than the present value, and discharge values near the face of the melting ice sheets 100 times greater than present stream-flow in the area. Dury (1976) later modified these estimates with more data, and a better meander geometry-discharge relationship. The revised values came out to 18 and 66 times, in place of 25 and 100 times. He (Dury, 1976) also found consistent relationships between meander wavelength, bed width, drainage area, and several other variables. Dury attributes the much higher discharges of paleorivers to higher precipitation during the ice age, and to melting of the ice sheets. The above figures for past river discharge are difficult for most uniformitarian scientists to accept. They may be able to explain terraces due to glacial/interglacial oscillations, but the lack of greatly increased rainfall during the ice age, and the slow presumed melting of ice sheets, taxes the uniformitarian model. Strahler (1987, p. 291) states the problem very well:
Nevertheless, the requirement of former stream discharges as great as 20 to 60 times those occurring [sic] today presents a difficult problem for mainstream science, which insists that principles of atmospheric science and hydrology be applied in a reasonable manner.
Consequently, various aspects of Dury’s data have been questioned-specifically, the validity of extrapolating the present meander geometry-discharge relationship to the past, whether discharge refers to bankfull river flow or to floods-and the influence of additional variables that have been neglected. Perhaps the most favored additional variable is the type of sediment transported by the river. Schumm (1967, 1977, pp. 113-119) claims that a coarser bed load will cause significantly larger meanders, and will reduce the scatter in Dury’s meander-wavelength-discharge data. According to Strahler (1987, p. 291):
Given two streams of equal mean annual discharge (or equal mean annual flood discharge), the one transporting a high proportion of its load as bedload of mixed sand and gravel will have a meander size (wavelength) larger by a factor of approximately 10 than the stream carrying mostly clay, silt, and fine sand held in suspension. Does a difference of ten times, due to the type of bedload, seem reasonable? The effect of bedload character is controversial. Undoubtedly, bedload has some effect on meander wavelength, but several investigators have found that it is a small and relatively unimportant factor (Williams, 1988, pp. 328, 329). Bedload is not significant enough to be included as a second independent variable in a multiple-regression equation. A number of investigators, over the years, have demonstrated an excellent correlation between only meander wavelength and discharge. For instance, Williams (1988, p. 329) lists one report in 1965, which contained an equation that closely describes 31 rivers-mostly in the central United States. This equation showed even higher discharge for a given meander wavelength than given by Dury’s wavelength-discharge equation. A restudy of Dury’s original graph of meander wavelength versus discharge (Schumm, 1977, p. 116) revealed that the order of magnitude of scatter, which Strahler claimed could be explained by the type of sediment carried by the river, was mainly a characteristic for lower discharge rates. The fit of the data was very good at higher discharges rates, which are of more interest for paleorivers. Furthermore, Dury (1976, p. 222) has refined and updated his graph. His newer data fit closely a regression line that accounts for 87% of the variance. There is adequate evidence that Dury’s relationship between meander wavelength and discharge rate, and his conclusions about past river flow, are sound.
What about Schumm’s data and claim that bedload is a significant variable? One of his most significant items of data, from Australia, is disputed by Dury (1977, p. 71), and also by others. Moreover, the type and quantity of sediment discharged through former channels, is mostly unknown (Dury, 1976, p. 228; Williams, 1988, p. 324). Only rarely can bedload characteristics be specified for a paleoriver. Williams (1988, p. 324) adds that Schumm’s bedload parameter “... may not apply to environments other than that for which it was deduced....” In summary, Schumm’s additional variable of sediment load does not invalidate the good correlation between meander wavelength and river-discharge rate that has been established by Dury and other investigators. An extrapolation of this relationship to paleorivers indicates that past river discharge estimates of over 60 times current values in some areas, are justifiable. This consideration supports the Flood model better than a uniformitarian model for the ice age.
Massive Extinction of Megafauna
If the association of animals from diverse climates during the ice age is mysterious, the extinction of many of these large animals, as well as birds, at the end, is just as mysterious. At this time, the climate was supposedly warming, according to most uniformitarian theories. A related mystery is the massive extermination of the woolly mammoth, in Siberia and Alaska. Since the woolly-mammoth problem is a special case and has a long history of controversy, it will be treated in the next section. This section will offer a post-Flood explanation for the demise of much of the ice age megafauna, and will introduce the climatic background for treatment of the woolly-mammoth extinction problem.
According to the uniformitarian model, the megafauna species, and/or genera, survived each previous glacial and interglacial period. But at the end of only the last ice age, many large mammals became extinct, or disappeared from entire continents. These mammals include mammoths, mastodons, saber-toothed tigers, and ground sloths. North America was especially hard-hit, with about 34 genera of large mammals becoming extinct, compared to only 7 to 15 (depending on the investigator) in all the previous Pleistocene “ice ages” (McDonald, 1984, p. 415). Moreover, the largest species were preferentially decimated; and, in contrast to other extinctions in the geological record, the mammals were not replaced, in their habitats, by other animals (Lewin, 1987, p. 1509). To compound the mystery, these mammals ranged over North America, Europe, and Asia, and had broad climatic tolerances. The mystery of their extinction remains unsolved after 200 years of effort. Bruce Bower (1987, p. 284) states the problem well:.
What caused the virtually simultaneous demise of mammoths, mastodons and saber-toothed cats, not to mention native horses, ground sloths, native camels, armadillo-like glyptodonts, giant peccaries, mountain deer, giant beavers, four-pronged antelopes, dire wolves, native lions and giant short-faced bears? Scientists have grappled with this question for nearly two centuries, and, as evidenced by a recent symposium at the Smithsonian Institution in Washington, D. C., the debate is not about to cool down.
Grayson (1984b, p. 807) expresses the mystery as follows:
We have accumulated facts on the nature of ancient floras and faunas, on past climates, on human prehistory, and on the chronology of it all. These are precisely the kinds of facts that scientists have assumed all along are needed to provide an adequate explanation of late Pleistocene extinctions. Nonetheless, from an historical perspective one of the most interesting lessons to be learned from this volume is that we are apparently no closer to that adequate explanation, or at least to agreement as to what that adequate explanation is.... In other words, scientists are no closer to agreement, after 200 years of gathering data, which should have brought greater understanding. The problem, likely, is in their uniformitarian assumption. A few scientists involved in the investigation of the mystery, have admitted the inadequacy of this rigid constraint. Guthrie (1984, p. 292) candidly writes:
Looking at the extinction problem through the eyes of a young paleontologist in the early 1960s, I encountered my first important lesson-that the present can be used to understand the past only with sensitive discretion. In fact, much of the past may have no modern analogue.
Guthrie is essentially saying that the uniformitarian assumption is almost useless. It will be argued here that the environment following the post-Flood glacial maximum provides a probable cause for the extinctions.
Before discussing this solution, a summary of the main uniformitarian arguments for these extinctions will be given. These arguments are instructive, and have a bearing on a post-Flood ice-age explanation, since the treatment given by uniformitarian scientists is partially correct.
Two main theories of Late Pleistocene extinctions are currently debated (Martin and Klein, 1984). One theory states that climate change at the end of the ice age killed the animals, and the other theory claims man killed them, in a great slaughter. Those who believe climate change is the culprit, point to the harsher climate at the end of the ice age, but “overkill” theorists ask why the last glaciation should be any different from the previous 20 to 30 postulated Pleistocene glaciations.
Overkill enthusiasts claim the extinctions in North America coincided with man’s conquest of the New World, at about 11,000 years ago, in their dating scheme. Climate theorists counter by questioning the exact date. Krishtalka (1984, p. 226) points out: Their selective acceptance of only the “good” dates-those that fit the model (for example dates for human beings in North America no older than 12,000 yr BP, and those for mammoths no younger than 10,000 yr BP)-may play fast and loose with the evidence that doesn’t fit.
Grayson reinforces the above comment with this eye-opening quotation: “The timing of Ice Age extinctions is really very poorly understood.... Radiocarbon chronologies are bad in North America and worse in Europe” (Bower, 1987, p. 285).
Those who support climate change as the principal factor, doubt whether man could have killed all those animals, especially since some of them ranged over most of the Northern Hemisphere. Animals that were not obvious prey to human hunters also became extinct (Lewin, 1987, p. 1509). Even ten classes of birds, mostly scavengers, became extinct in North America (Bower, 1987, p. 285). It is significant that primitive man did not kill off many large animals in Africa. If man was responsible for the mass slaughter, why did he not wipe out large, edible mammals like moose, elk, deer, and bison, in North America and Europe?
Overkill theorists charge that large mammals can easily migrate as the climate changes, and can better survive the cold (McDonald, 1984). Furthermore, the climate must have warmed, in order to melt the ice, and less ice should have provided more land for grass to grow. Proponents of the opposing view counter that, although the average climate was warming, the climate was also more continental, with colder winters and warmer summers. Fewer species of animals live in modern continental climates (Guthrie, 1984, pp. 287,288). A drier climate, while the ice sheets melted, would also favor smaller animals who needed less food. So on and on the debate goes, each side making strong points. The reader can appreciate the quandary the experts are in. Most scientists have adopted some sort of compromise position (Anderson, 1984, p. 41). Can a post-Flood ice age account for the extinction of many large mammals? The answer is yes. First, the animals thrived during the ice age because the climate was wetter, with milder winters, in contrast to uniformitarian expectations. Although large animals can survive the cold better than small animals, they can do so only if enough food is available. A wetter climate would provide adequate food. During the development of the ice sheets, the climate wasn’t cold enough to cause animal extinction. As the ice sheets melted, winters became colder and drier-not warmer, as some authorities believe. Consequently, the largest animals would be the most stressed, due to lack of food. Many could have migrated, but, if the change was relatively sudden over a large area, they would have starved to death, by the time they found a suitable habitat.
Here is where man, the hunter, enters the picture, to finish the job. Man, who by this time had spread over most of the world, would also have been stressed by the harsher climate. Fruits, vegetables, and grains would have been scarce. He would have found these large mammals to be good hunting prey, and, possibly, the only food available. The fact that man did hunt the large animals, especially mammoths and mastodons, is shown by Neanderthal and Cro-Magnon cave paintings of these animals (Sutcliffe, 1985, pp. 82-104). In North America, 14 mammoths, with spear or arrow points embedded into the bone, have been found (Marshall, 1984, p. 790). Arrow points have also been found in mastodons in North America, and in a toxodon in South America (Nilsson, 1983, pp. 415, 428). Burned bones of several other animals have been found with presumed human cultural remains.
We may conclude that man probably took part in the extinction of many large mammals; but, as the survival of other large animals attests, man was not completely responsible for the extinctions. Climate change is the other culprit. The reason for very few extinctions after other uniformitarian ice ages, is that there weren’t any other ice ages.
While on the topic of extinction, something should be said about fossilization during the ice age. Fossilization is a rare event in the present world, but was common in the ice age. How did so many animals become buried and fossilized at that time?
Before glacial maximum, high volcanism could have trapped and buried some animals in ash, similar to when the eruption of Mt. Vesuvius buried the Roman city of Pompeii. In addition, heavy precipitation in non-glaciated regions would at times have caused severe flooding, which would have rapidly buried some animals.
During deglaciation, the cold, dry climate severely stressed the animals. Caves would have been good shelters. Many animals would have died of the cold, or starved in these caves. Caves are rich sources of ice-age mammals: “The quantity of mammalian remains found in caves and their fine state of preservation is sometimes astonishing” (Sutcliffe, 1985, p. 74). Rapid melting of the ice sheets caused large seasonal floods, rapidly trapping and entombing animals. Some animals became caught in violent dust storms south of the ice sheets. They would die of suffocation, and the dust would rapidly bury and preserve them. Fossil mammals are occasionally found in loess (Sutcliffe, 1985, p. 43). In areas close to the ice sheets, permafrost developed. When the top layer of permafrost melts in the summer, the mud is very sticky, and can flow down a gentle slope. This is called a gelifluction flow, and can sometimes bury an animal before it decomposes. Sutcliffe (1985, p. 41) relates about how 25 reindeer became trapped in a gelifluction mud flow in the Northwest Territories of Canada, in 1947. Local herders managed to pull 18 out, but the other seven were buried within a short time. It is evident that, during the ice age, the climate and environment provided many opportunities to trap, bury, and fossilize an abundant representation of the animal population.
Woolly Mammoth Extinction in Siberia and Alaska The bones and carcasses of woolly mammoths unearthed in Siberia and Alaska, have taxed the imagination of scientist and layman alike. Explanatory theories are numerous. Most scientists adhere to the uniformitarian assumption, while some laymen have suggested strange catastrophes. For example, Charles Hapgood (1970, pp. 249-279) postulates a large, northward shift of the Siberian crust of the earth after the ice age. This shift, along with extensive volcanism and strong winds, presumably cooled Siberia, and killed the mammals. The woolly mammoth cannot be isolated from the other late Pleistocene megafaunal extinctions discussed in the previous section. Mammoths completely died out all over the Northern Hemisphere during deglaciation. Hundreds of thousands, or perhaps millions of them died in Siberia and Alaska. The woolly mammoth, and the other mammals that were associated with it, are found, most abundantly, close to the Arctic Ocean, and on the islands off the coast (Stewart, 1977, p. 68). The frozen carcasses have especially attracted attention, as indeed they should. They are only found in the area of permafrost which has preserved them to this day. Most of the mammoth carcasses are of animals that, apparently, were healthy and robust before they died. Some had eaten just before their death. The cause of death in at least some cases was by suffocation, or asphyxia. Farrand (1961, p. 734), reiterating the standard uniformitarian opinion, states: The only direct evidence of the mode of death indicates that at least some of the frozen mammoths (and frozen woolly rhinoceroses as well) died of asphyxia, either by drowning or by being buried alive by a cave-in or mudflow. As stated above, sudden death is indicated by the robust condition of the animals and their full stomachs.
Evidently at least some of the mammoths died suddenly, by suffocation, and were buried before major decomposition occurred. The number of frozen carcasses must be kept in perspective. As of 1929, there were only 39 known carcasses of woolly mammoths and rhinoceroses (Tolmachoff, 1929, p. 20). Only about a half-dozen of these were actually complete; most were only a few small remnants of soft tissue attached to bones (Tolmachoff, 1929, p. 41). Since 1929, several more carcasses have been unearthed, including a baby mammoth discovered in 1977 (Stewart, 1977, 1979; Dubrovo et al., 1982).
Many more carcasses than are known must have existed, and must still exist in the frozen ground, because a carcass may completely rot before the sparse, superstitious, and fearful population of Siberia notice and report it. Often the carcass can decompose before a scientific expedition is organized to retrieve and find it in the barren, almost impassable terrain (Dillow, 1981, pp. 328-334). Most carcasses that have become exposed have completely decayed, without leaving a record. Tolmachoff (1929, p. 41) estimated that the number of carcasses, with some remaining soft parts, probably is hundreds or thousands of times more than known. This would bring the number of carcasses, or partial carcasses, up to about 50,000, which is still small, compared to the million or more that likely have been entombed. Consequently, most mammoths must have decayed completely, before, or while becoming interred in the permafrost. And the carcasses that are found show signs of partial decay before final freezing and burial in the permafrost.
Besides the small number of known carcasses, there are several other reasons for the conclusion that remains with flesh are rare. First, the mammoths are usually discovered while being eroded, and are practically always limited to bones and tusks (Tolmachoff, 1929, pp. 11-20; Stewart, 1977). Second, many bones and tusks were discovered by ivory hunters, who would be more willing than the few inhabitants to report a carcass. Third, a carcass can remain, at least partially intact, upon exposure, for several years before complete decay (Tolmachoff, 1929, pp. 24, 31, 60), increasing the odds that it would be discovered and reported. The stomach contents of a few mammoth carcasses have heightened the mystery. Surprisingly, the stomach contents were only half digested-a condition believed to occur only if the mammoth cooled very quickly. Specialists from Birds Eye Frozen Foods Company concluded that the state of preservation of the stomach contents suggested an atmospheric temperature drop of below-150°F (Dillow, 1981, pp. 383-396).
Many of the plants in these stomach contents could still be identified. Some scientists have claimed that these plants indicate a much warmer climate, while others have claimed that they represent types found in the current Arctic tundra. The stomach contents have also led to the conclusion that the time of death was late summer or early fall. Since beans and other vegetation were found in the teeth of one carcass, the mammoth must have died while eating its last meal. Thus, a catastrophe seems to be the logical conclusion. But what kind of catastrophe? This depends upon the “facts” in the case, and the possible explanation of those facts. A close examination of what is known about the death of the woolly mammoth is needed. A million or more mammoths that apparently were killed and buried in the permafrost suggest a climatic catastrophe. The climate must have been wetter and winters milder while they lived there. The permafrost must not have existed at the beginning of the catastrophe. Since the flesh has remained frozen to this day, the animals were buried while the permafrost developed. The catastrophe brought a permanent cooling of the climate. The rate at which the change in climate developed is an important consideration.
Since practically all the mammoth flesh decayed before, or during burial, the climate change could not have been a quick freeze. The small number of frozen carcasses is about what one would expect, by chance. In other words, the frozen carcasses are the result of rather rare conditions, involving rapid burial. It is clear that the mammoths were not quick frozen at-150°F and abruptly buried. Theories attempting to explain the frozen carcasses focus on the rare find, which could be due to rare, local conditions of preservation, and not to an instantaneous catastrophe of regional scale. The great number of animals that underwent normal decay and burial should be the actual basis for a theory of their demise.
Further evidence against a quick freeze is shown by the famished condition of the baby mammoth found in 1977, as proven by its lack of fat, and its ribs pathetically showing under the skin. If this mammoth was healthy before the catastrophe (as other carcasses were), its poor physical condition would take time to develop during the catastrophe. In addition, the contents of the skull were a putrified, structureless mass, which would not be the case in a quick freeze. The decay did not occur after becoming unearthed, because the carcass was actually bulldozed from below six feet of sediments, after being spotted in an ice wedge. A third piece of evidence against a quick freeze, is that most of the remains are mammoths. Many other types of animals that were more fleet, lived with the woolly mammoth, and practically all escaped the catastrophe, probably by migrating out of the area. This would take time. A sudden drop in the temperature to below-150°F would stop all animals in their tracks.
Then how can the condition of the stomach contents be explained without a quick freeze? We may never know the answer. Dillow (1981, pp. 380, 381) reasons that the state of stomach-preservation would have occurred, if the stomach temperature was reduced to 40°F in ten hours. This figure seems reasonable, but should be further evaluated. The reason for suggesting a quick freeze below -150°F is to produce a ten-hour cooling of the stomach to 40°F. There is a need to check into other possibilities that could account for the state of preservation of the stomach contents. Is there any other mechanism that can stop, or slow down the digestive processes immediately after death? This author has thought of several possibilities, but, so far, they are only speculation, without much knowledge of the mechanisms involved. The suggestion that other possibilities do exist is supported by preserved wood fragments from the stomach of a mastodon excavated in the warm country of Venezuela (Sutcliffe, 1985, p. 37).
What is the evidence, so far? First, a million or more well-fed mammoths, along with many other types of mammals, lived in a climate much warmer than at present, and with no permafrost. Second, the climate became much colder, resulting in the death of the mammoths, and the preserving of their remains in permafrost, which developed at the same time. The cooling was relatively rapid (otherwise, the mammoths would have been able to migrate out of Siberia) but not so rapid as to prevent most of the other animals from escaping. Third, since there are so few frozen carcasses, the catastrophe was not a regional quick freeze, as some popular accounts suggest. Most mammoth carcasses decomposed before burial, allowing enough time for normal decay. Fourth, after burial, the soil remained frozen to this day. The climate change to colder conditions was permanent. Taken together, the evidence indicates that the climate change was a relatively rapid and permanent shift from mild weather to a very cold climate.
Such a climate shift would occur at the end of a post-Flood, rapid ice age. Siberia and Alaska would have been much different during the ice age than today, with warmer temperatures and more moisture for plant growth (Chapter 5). As the ice age progressed and the Arctic Ocean cooled, these areas would also gradually cool. The animals living there would have been able to adapt, somewhat, to cold. The winter temperatures would still have been significantly warmer than they are now, as indicated by atmospheric simulations with an ice-free Arctic Ocean (Newson, 1973).
During deglaciation, the climate of Siberia and Alaska would turn colder, and drier, than it is at present. The melting ice sheets would provide fresh water for the Arctic Ocean. This fresh water would float on the denser salt water, and cause the rapid formation of sea ice, reinforcing the colder temperatures. Consequently, Siberia and Alaska, previously kept warm by an ice-free Arctic Ocean, would rapidly turn much colder.
Many animals had enough time to migrate to a less severe climate during deglaciation. The slower-moving mammals would, more likely, become trapped. The natural tendency for the mammoth, likely would have been to migrate to where the climate was always warmer in winter-towards the Arctic Ocean and away from the continental interior. But under the new climatic regime, north was the wrong way to go; and they died of the cold, in droves. The carcasses found with partially digested food in their stomachs may have suffocated after passage of a strong late summer or early-autumn cold front, accompanied by strong wind. The wind-chill factor can greatly enhance the cooling efficiency of the cold temperatures. For instance, at a temperature of -20°F and a wind of 30 miles per hour, the air can cool an animal as if the temperature was -78°F, and the wind calm. Cold wind has been known to suffocate and freeze cattle every year on the high plains of the United States (their nasal passages become blocked with ice).
Practically all the woolly mammoths decayed before final burial and freezing of the soil. Some, however, happened to be buried quickly enough to partially preserve their flesh. As the icecaps in the Asian mountains rapidly melted, the rivers of Siberia would be swollen with water and sediment. As the permafrost developed, the water could not soak into the ground. Gigantic floods would have occurred during rapid deglaciation, producing vast flood plains, especially close to the Arctic Ocean. In fact, Siberian rivers today swell to very large volumes in early summer because of snowmelt from huge drainage basins, and because the permafrost causes ground water to run off, instead of being absorbed into the soil (Untersteiner, 1984, pp. 137-139). The dead animals would be buried in this sediment at the beginning of deglaciation. Much of northern Siberia is one vast flood plain today, which is the result of the melting mountain icecaps. After depositing an alluvial flood plain, the rivers would eventually erode the alluvium, forming valleys and terraces. Thus, the mammoth remains would be left on the highest terraces, or bluffs, of modern or ancient rivers. This is where they are mostly found today. The climate at the end of a post-Flood, rapid ice age answers most of the questions surrounding the death of the woolly mammoth in Siberia and Alaska.