08. How Long Ago?
CHAPTER 8
How Long Ago? A date for the end of the ice age would be of interest, in itself. But, this date would also indicate the approximate time of the Genesis Flood, and whether the Biblical time framework can be supported objectively. The scientific community predominantly believes that the last ice age peaked about 18,000 years ago, and that the Laurentide and Scandinavian ice sheets melted northward, and completely disappeared about 8,000 years ago. Is there any evidence that would indicate whether the ice melted 8,000 to 18,000 years ago, or in a shorter time-for instance 3,000 to 5,000 years ago?
There is evidence for a relatively recent melting of the ice, but this evidence is mostly qualitative. Unfortunately, our recreation of past phenomenon depends upon assumptions and on backward extrapolation from present measurements of chronological variables. A date for the end of the ice age can be estimated from post-ice-age landscape alterations. Such analysis comes under the classification of geomorphology. Some of these landscape changes include the recession of waterfalls, like Niagara Falls, which formed after the ice left the region; the erosion of till by post-ice-age streams and rivers; and the sediment-filling of lake beds formed in the till. By calculating the current rate of change, and measuring the total erosion, or sedimentation, a date for ice recession can be qualitatively estimated. But approximate calculations are not straightforward. It is highly unlikely that the current rate of change can be extrapolated for all the past. And several other variables, usually not accounted for, affect the accuracy of the calculations.
Very few geomorphologists, today, date the end of the ice age by landscape alterations. Scientists now rely almost exclusively on radiometric and fossil-dating methods (Sibrava et al., 1986). Because these methods are fitted into the popular model for geological time, the model usually determines the dates and the results that are “found.” The popular model now is the multiple ice age model, in which 20 or more ice ages are assumed, based on ocean-sediment data. Fitting land sequences of till into such a model is impossible, on the basis of only macroscopic features. The main sources of data concerning landscape changes that bear on the date when the ice sheets disappeared, are in the earlier literature. Many of these early workers were keen observers, who reported their observations fully, and were not too constrained by existing models. For instance, Antevs and Chalmers, around the turn of the century, claimed that ice moved northward from northern New England down the regional slope and into the St. Lawrence lowlands. This northward movement did not agree with the model of a thick ice sheet that developed in Canada and swept southward into the United States. Consequently, geological surveys, carried out as recently as the 1960s, “firmly established” that the last ice movement in the area was towards the south, or southeast. Now, however, field evidence from glacial-flow indicators shows abundant and overwhelming proof of northward ice flow (Chauvin et al., 1985). The earlier observations were correct, after all-probably because the early glacial geologists were unencumbered by too many assumptions and models.
Most Glacial Features Altered Little
Many investigators have pointed out the old appearance of glacial deposits in the north-central United States, south of the boundary of the “last” glaciation. The deposits are well weathered; the topography is subdued and eroded. This area is called the attenuated border by many glaciologists, and was explained within the context of a rapid ice age in the previous chapter.
Northward from this attenuated border, the glacial deposits look fresh. As stated in Chapter 1, streamlined till can be seen from the air, in many areas. If the drumlins and grooves had not been formed recently, erosion would have smoothed them out. In another instance, G. Fredrick Wright (1911, p. 569), quoting the work of another scientist, writes: On Portland promontory, on the east coast of Hudson’s [sic] Bay, in latitude 58°, and southward, the high, rocky hills are completely glaciated and bare. The striae [scratched rock] are as fresh looking as if the ice had left them only yesterday. When the sun bursts upon these hills after they have been wet by the rain, they glitter and shine like the tinned roofs of the city of Montreal.
Striae should be erased rather quickly after exposure, but their fresh appearance on bare rock east of Hudson Bay and in many other areas, indicates the ice disappeared a relatively short time ago.
Wright, quoting many observers, adds further that little erosion of glacial features has occurred in the state of Wisconsin, and that glacial kames, in Europe and North America, are only slightly eroded. Charlesworth (1957, pp. 507, 508) also notes the abundant signs of very slight post-glacial erosion:
... postglacial remodelling is still in its infancy. The decay is often scarcely appreciable on roches moutonnées, grooves and striae as Sefström noticed. Cirque-lakes have frequently only insignificant notches in their outer rim, and even large streams have been able to cut only extremely youthful trenches in the steps of trough-floors and the lips of hanging valleys. Cirque-cliffs, e.g. the Spiegelwände of Zillertal, are often still fresh and the dismantling of the walls of U-valleys has made little progress since talus cones are few... Minor and more delicate topographic forms are scarcely touched; moraines stand out as bold and steep embankments; outwash sheets are but slightly dissected.... Drumlins retain their perfect form....
Many other writers have made similar comments. The only sound conclusion is that the ice melted from the glaciated area recently. At the time Wright was writing, geologists believed the ice age ended about 70,000 years ago, because of “... the almost unquestioned acceptance of the astronomical theory...” (Wright, 1911, p. 532). Wright was primarily writing to show that geomorphological data indicated the ice age did not end 70,000 years ago. As a result, his calculations for the end of the ice age are most likely too old. His estimate was about 10,000 years ago. A contemporary observer, Warren Upham, believed the end of the ice age was 5,000 to 10,000 years ago (Wright, 1911, p. 522).
Estimated Time Based on Erosion
We will take a further look at Wright’s data, to see if the date for the end of the ice age can be quantitatively narrowed down. The most thoroughly investigated post-glacial time indicator is the erosion of Niagara Gorge. From surveys taken over the past 150 years, the average rate of recession of Niagara Falls (Horseshoe Falls) is about five feet/year. If this rate is assumed constant, the ice sheet left this area 7,000 ago. However, several complications make this estimate untrustworthy. First, several other Niagara river channels are known-one of which is filled with glacial drift (Philbrick, 1970; Calkin and Brett, 1978). Second, the Great Lakes probably drained through several other outlets for a short time, greatly reducing the flow of the Niagara River, and the resulting erosion of the Niagara Gorge (Karrow and Calkin, 1985). These complications would increase the real time. From a rapid ice age perspective, channels now filled with till more likely were cut by the draining Flood waters. Although the Great Lakes probably drained through other outlets, at times, during deglaciation, most of the drainage was by the Niagara River since northern drainage outlets were often blocked by ice. These outlets probably were lower at the end of the ice age, based on north-south tilted shore lines indicating greater isostatic depression north of the Great Lakes. Since the melting rate in a post-Flood ice age is much faster than uniformitarian estimates, the Niagara River, at one time, would have had a flow greatly in excess of modern observations. This would have significantly increased the recession rate. An analysis of how the Niagara Gorge recedes shows that the river first erodes the soft shale at the bottom of the canyon, causing the hard limestone at the top to break off in blocks (Gilbert, 1907, p. 5). These blocks then protect the soft shale from further erosion until the waterfall wears the limestone away. In high-flow years, the falling water wears away these limestone blocks more rapidly, resulting in a more rapid recession of the gorge. A quantitative estimate of the effect of high flow can be found by comparing the two branches of Niagara Falls: the Horseshoe Falls and the American Falls. American Falls carries only about 10% of the water, and its average erosion rate for the past 500 years, when the two falls separated, has been 0.32 inches/year. Horseshoe Falls erodes 15 times faster than American Falls. On this basis, the average erosion-rate ratio is about 1.5 times the ratio of flow rate. For a flow rate during deglaciation ten times the current rate, the rate of recession of Niagara Gorge would be 75 feet/year. But if the flow were 50 times more, recession would be 375 feet/year, assuming the 1.5-ratio holds for all flow rates. However, these estimates are conservative, because the ratio of erosion-to-flow rate is probably more an exponential function of the flow ratio. With an exponential relationship, the recession of Niagara Gorge would be much higher than the simple linear estimates given above. Since the gorge is only six miles long, the entire length of the gorge could have been cut in 500 years and 100 years, respectively, at the above linear rates. Of course, we do not know how long the Niagara River was swollen with huge volumes of meltwater, nor how long the ice north of the Great Lakes prevented most of the water from flowing through other outlets. Previous calculations showed the ice would completely melt along the periphery in about 100 years. According to a rapid ice-age model, the cutting of the gorge would have been rapid for perhaps a 100-year period, and then would have slowed to the present average rate for perhaps 3,000 more years. The combination could erode Niagara Gorge in perhaps 3,000 to 4,000 years. The recession of St. Anthony Falls in Minneapolis, is a similar time indicator. Extrapolating the present recession rate (before the falls were made stationary), the river would have cut the post-glacial gorge in about 7,800 years (Wright, 1911, pp. 552-560). The same considerations regarding a much higher flow rate as were used for Niagara Falls, apply to St. Anthony Falls. Thus, the estimated time for the recession can be reduced, significantly, below 7,800 years. The estimates of recession of Niagara and St. Anthony Falls, unfortunately, are still more qualitative than quantitative. A more quantitative estimate can be found by estimating the rate at which Niagara Gorge has widened with time. Wright (1911, pp. 548-552) calculated the amount of erosion on the east side of Niagara Gorge near its mouth, which was formed at the time of ice removal from the area. Assuming the 340-foot-high gorge was originally vertical, 388 feet of rock has been horizontally removed from the top since the ice melted (Figure 8.1). How long would this take? This estimate is independent of much higher river flows during deglaciation, and to a first approximation should be constant since the ice melted. This approximation depends primarily on the year-to-year weather patterns since deglaciation, which likely have been similar to the present average-weather conditions. Wright states that if the average rate of removal, by erosion, from the face of the cliff, is only 0.25 inches/year, the material would have been eroded in less than 10,000 years. This is the age he favored.
However, the observed erosion is greater than 0.25 inches/year. A railroad track was laid, in 1854, that gradually climbed the east face of the gorge, from its mouth. Wright actually measured the average amount of erosion of the shale in the 55 years since the track was laid, as 1.5 inches/year. At this rate of erosion, the ice receded only 1,667 years ago.
Wright considered how the above rate could have been slower, in the past. But, he concludes, “... the Niagara shale has not been protected to any extent by a talus, and but slightly by vegetation” (Wright, 1911, p. 552). He did not consider the possible retarding effect of the harder limestone, but the limestone at the top of the gorge, and another smaller limestone layer midway down the gorge, should not slow the overall erosion much. The limestone should fall off as blocks at about the average rate of erosion of the underlying shale. The blocks would fall into the river and offer no protection to the erosion of the shale, unlike the situation for the recession of the waterfall. Unless the rate of erosion was significantly less in the past, this more quantitative conclusion indicates that the ice left the area only about 2,000 years ago.
Plum Creek, in Oberlin, Ohio, developed after the ice melted from the area. It has been eroding entirely through glacial till since its origin. Based on the volume of till eroded and the current rate of erosion, Plum Creek eroded its small valley in about 2,500 years (Wright, 1911, pp. 565-567). Unfortunately, other complicated variables make this estimate rough. For instance, after a reservoir was constructed, and a portion of the stream diverted, the new stream eroded the new channel at only 63% the rate of the undisturbed stream. If the diverted stream erosion rate is the average for Plum Creek since the ice melted, the erosion time would be extended to 4,000 years. A dense forest, which once grew in the Plum Creek drainage basin, would slow the erosion rate. But the forest covered the area for only a short period. Furthermore, the rate of erosion of Plum Creek, now should be at a minimum. These calculations, although rough, indicate that glacial ice left the area on the order of 3,000 to 4,000 years ago. In summary, qualitative data for the area north of the line of the “last” glacial advance, in the north-central United States, shows that glacial features were formed relatively recently. Landscape changes since the ice left the region provide the best method for a quantitative estimate of the time when the ice sheet melted. However, little data is available, because of the modern dependence on radiometric and fossil-dating methods. The data that is available is old, but seems to be reliable. Although based on assumptions-some good and some poor-the estimated time since deglaciation is as little as 2,000 years. A more reasonable estimate, for the time since the glacial ice melted, is probably 3,000 to 4,000 years.
Eustasy and Isostasy The topic of eustasy and isostasy, although briefly alluded to already, will be discussed in more detail, in this section. These phenomena have continued into the post-ice-age period, and even up into modern times.
During the post-Flood ice age, sea level would have lowered rapidly-much more rapidly than has been estimated from the uniformitarian time scale. Melting of the ice sheets within 100 to 200 years would have raised sea level rapidly. This type of sea-level change is called “eustatic.” Figure 8.2 is a postulated graph of eustatic sea-level change, compared to today’s average sea level, for a post-Flood ice age, and afterwards. Immediately following the Flood, sea level begins about 40 meters higher than at present, since the Antarctic and Greenland ice sheets had not yet formed. If these two ice sheets melted today, 60 meters of water would be added to the ocean. But due to isostatic compression (which will be discussed next), the ocean basins probably would sink enough to limit the total rise in sea level to only 40 meters.
Although their curve was incomplete, Blackwelder et al. (1979) estimated a sea level at about -50 to -70 meters during maximum glaciation, based on “non-moveable” sea-level indicators. They conclude:
Compared to other sea level curves, our data indicate that substantially less ice was present from 17,000 to 10,000 years B. P. Our data strongly suggest that the late Wisconsinan maximum regression was not as profound as has been indicated in the literature (Blackwelder et al., 1979, p. 620).
Besides eustatic changes in sea level caused by glacial melting, there also would have been isostatic, tectonic, and geoidal changes. All these variables are complicated and difficult to measure and isolate from one another. It is evident that reports of sea-level indicators below 50 or 60 meters cannot really be taken as firm evidence that sea level actually was below that value. In fact, the eustatic component of sea level really cannot be measured at all, as admitted by Dawson and Smith (1983, p. 373):
However, these advances have coincided with the discovery that a global ‘eustatic’ sea level cannot be measured anywhere... and that regional differences in Holocene sea-level curves may be explained by ocean floor deformation and geoidal deformation of the ocean surface caused by changing ice and water loads.
After maximum glaciation, the Laurentide and Scandinavian ice sheets would melt rapidly. But the Greenland and Antarctic ice sheet would still be growing at significant rates, due to the relatively warm oceans surrounding them (10°C at glacial maximum). Thus, the post-Flood eustatic sea-level rise, although rapid compared to uniformitarian standards, would be more gradual than estimated from a simple model. Immediately after the Laurentide and Scandinavian ice sheets melted, sea level should have been a little higher than today, because the Antarctic and Greenland ice sheets yet would not have reached their present size (Figure 8.2). Sea level would then slowly descend to near the current value.
Another phenomenon of interest and potential conflict with uniformitarian ice age models, is the depression and rebounding of the earth’s crust, due to changes in the amount of either ice, on land, or water, in the ocean. This vertical motion of the earth’s crust, due to a changing load, is called isostasy.
Isostatic depression and rebound have been observed directly, and there is excellent evidence for their occurrence in the past. For example, when Lake Mead, in Nevada, was filling with water, the extra weight of the water caused a 20-centimeter subsidence of the crust (Dott and Batten, 1976, p. H7). As discussed in Chapter 4, at the beginning of the ice age, Lake Bonneville was about 285 meters higher than the current Great Salt Lake. Interestingly, the highest shoreline of this ancient lake is bowed upward as much as 70 meters higher towards the middle of the lake, where the lake was the deepest (King, 1965, p. 850). By using only the highest shoreline, arguments as to the exact chronology of lower shorelines is avoided, since shorelines are mostly spotty, and their matching is subjective. The rebounding of the land during and after the melting of the Laurentide and Scandinavian ice sheets, is well known. Modern sea-level measurements in the Baltic Sea reveal that the land is currently rising at about one centimeter/year. Many recent shorelines are easily visible around Hudson Bay and the Baltic Sea (Fairbridge, 1983; Gudelis and Königsson, 1979). These shorelines are post ice age, and not due to a higher sea level immediately after the Flood, since the glaciers would have obliterated preceding shorelines.
Measurements of the geoid and gravity anomalies reveal that isostatic rebound, in areas formerly glaciated, is likely not yet complete. The geoid is the difference between the actual sea surface and an ideal ellipsoid of the earth’s surface. Gravity anomalies are a measure of the deviation from the average gravity of the earth. Both reveal either less or more mass in the earth below the location where the anomaly is measured. Both the smoothed gravity anomalies and the geoid are negative over Hudson Bay and the Baltic Sea (Walcott, 1973; Strahler, 1987, p. 258). This suggests less mass in the earth below, probably due to the weight of the ancient ice sheets having pushed a low viscosity portion of the mantle horizontally outward from the ice-covered area. But negative gravity anomalies and a negative geoid do not automatically indicate incomplete glacial rebound, since many other variables are involved. Walcott (1973, p. 20) states: “Since there are examples of regions of positive anomaly that are rising, and negative anomaly that are sinking, it is not certain that the negative anomaly does, in fact, indicate residual vertical movements.” Shilts (1980, p. 217) says there is no firm evidence on the origin of the gravity anomalies in the Hudson Bay area. He thinks that part of the negative anomaly may be due to permanent structural features. In general, a negative anomaly usually does mean the crust is slowly rising. But due to the above observation and other complicating variables, the magnitude of the gravity anomaly due to ice load and hence the amount of incomplete isostatic rebound, is not really known (Walcott, 1970, p. 719; 1980, p. 6).
Besides indicating that isostatic rebound probably is incomplete, the negative gravity anomalies imply that mantle rock is probably flowing horizontally, into the negative area, from the surrounding region. This may be why the bottom of the North Sea is slowly subsiding, causing sea level along the coast to rise, and vice versa, in the Baltic Sea. However, some scientists believe that isostatic sinking of the North Sea floor has stopped, and the current subsidence is due to high sediment loading from river input (Fairbridge, 1983, p. 4). This is hard to understand, in view of the postulated isostatic recovery remaining from the last ice age, according to the uniformitarian model.
How fast will the land respond to ice-loading and unloading? Strahler (1987, p. 259) claims the process is much too slow for a rapid ice age: To fit even a single cycle of glaciation into the first 1,000 or 2,000 y. of post-Flood time would require a drastic reduction of the viscosity of the moving mass, something completely removed from serious consideration because of the actual conditions of depth, rock density, and temperature that must have prevailed then, as now.
Strahler is saying the viscosity of the mantle material that must horizontally flow is too high for significant motion on the time scale envisioned by any post-Flood, ice-age model. However, the real question should be: What really is the viscosity of the mantle? Strahler seems to indicate that the viscosity is known from geophysics. Actually, this is not true. The viscosity of the hot mantle is an educated guess, based on other phenomena-the significance of which depends on many assumptions in historical geology. The viscosity of the mantle is mainly inferred from the presumed post-glacial uplift of Hudson Bay and Scandinavia:
Historically the subject [isostasy] has been primarily of concern to the geophysical community since studies of the rebound of the crust following deglaciation have provided the only means by which one could infer the effective viscosity of the planetary mantle. The importance of this parameter of course lies in the fact that it is a fundamental ingredient in thermal convection models of the process of continental drift... (Peltier and Andrews, 1983, p. 299). In other words, the viscosity of the mantle, as well as the supposed motion of lithospheric plates, is really derived from glacial isostatic rebound, not the other way around. The next question is: How is the past rate of isostatic uplift determined? Isostatic uplift rate is determined by the assumed deglaciation history:
Geophysical models of glacial unloading for the major ice sheets have now attained a high degree of sophistication. However, their accuracy remains subject to, amongst other factors, the accuracy of inferred deglaciation histories (Dawson and Smith, 1983, p. 374). So the assumed deglaciation history determines the rate of isostatic uplift, and not the reverse, as presumed by Strahler. Notice that Dawson and Smith say “amongst other factors,” indicating that even more assumptions are needed besides the assumed deglaciation history. The above example is like so much of historical geology. One conclusion of historical geology is based on assumptions that are further based on other assumptions. A conclusion, or even an assumption, is used to bolster other conclusions and assumptions. Andrews (1982, p. 2) states how, “Sometimes... the inputs for one approach serve as a verification for another line of inquiry.” Consequently, circular reasoning abounds, and it is very difficult to find raw data that are untainted by assumptions, or that are not based on, or fitted into, some model. An example of isostatic rebound data that is likely based on a model, is given by Mörner (1980a, p. 260), who draws contours of postglacial uplift totaling 820 meters at the presumed center of the Scandinavian ice sheet. This is not based on actual measurements at the center of uplift, since the highest postglacial shoreline is a maximum of 290 meters (Eronen, 1983, p. 188). Values of uplift over most of Scandinavia are actually much less than 290 meters. Mörner’s maximum value is probably inferred by an ice sheet believed to have been about 3,000 meters thick. But the thickness of past ice sheets is, in itself, only an educated guess, based on uniformitarian assumptions and models.
Radiometric-dating methods, and, in particular, Carbon-14, are used to bolster the uniformitarian models. Isostatic uplift rates often depend upon Carbon-14 measurements on ancient shorelines. However, there are many references to discarded Carbon-14 dates, and complaints on how inaccurate the dating methods are. As an example, Walcott (1970, p. 719) states that Carbon-14-dated shorelines give an order of magnitude difference in the isostatic recovery time of Hudson Bay. As another example, Mickelson et al. (1983, pp. 12, 13) write:
We know of several hundred radiocarbon dates from the area and time range being considered here, but only 27 have been used in our chronology. All but wood dates have been rejected because of unresolvable contamination problems, and only wood dates that seem to be from stratigraphically significant materials have been used. Other dates could be used to construct other chronologies.
What the authors are inferring is that they are choosing only the dates that agree with their model, and that these are a small percentage of those available. The rejected dates are said to be from contaminated samples. But scientists do not deliberately select organic material that is believed to be contaminated. They are very careful to avoid contamination, since it is a well-known problem. More likely, the Carbon-14 dates did not agree with the model, so the samples were assumed to be contaminated.
Since so many scientists have faith in radiometric dating methods, a third example may be helpful, this time from the topic under discussion. Eronen (1983, pp. 183, 184) states: A substantial improvement in dating methods was achieved by the discovery of the 14C method of age determination, and it is this method that has come to occupy a crucial position in shoreline displacement research over the last 20 years or so. This has helped to solve many problems, but has still not carried research forward as rapidly as had been initially expected, and many points have arisen which complicate the interpretation of 14C dates in embarrassingly many instances.
Radiocarbon has been used to bolster old models and to develop new models. But this dating method, like all others, is based on unprovable assumptions, and I believe the method is more complicated than researchers state. In order to find the isostatic rebound rate, and hence mantle viscosity, numerical values from the presumed deglaciation history are needed. One must know how thick the ice sheets were, the time the ice sheets began to melt, how fast they melted, the crustal rebound since ice removal, and the incompleted amount of presumed isostatic recovery. All of these variables are unknown. The rate of uplift is probably a logarithmic function-rapid at first, due to the sudden melting of ice, then slowing with time. Maximum uplift has been about 290 meters for Scandinavia (Eronen, 1983, p. 188), and 315 meters for the Hudson Bay area (Fairbridge, 1983, p. 7). However, the average uplift for the total area glaciated is much lower than the above values. Most ice-age specialists believe the ice sheets were about 3,000 meters thick, and that they didn’t begin melting in northeast Canada until about 11,000 years ago. Based on a probable logarithmic decrease in uplift rate since 11,000 years ago, isostatic recovery should be finished in about 20,000 years or more. But this figure depends upon many complicated variables that are poorly understood. The model presented in this monograph would predict a faster isostatic recovery rate. The ice-sheet thickness proposed here is significantly less than uniformitarian estimates. Based on a thinner ice sheet, isostatic recovery, due to ice unloading, should be almost finished. The time since the ice sheets began to melt, possibly is around 3,000 or 4,000 years. This value indicates complete isostatic recovery, probably in about 5,000 to 10,000 years. A faster isostatic recovery rate also implies a lower mantle viscosity, which may have further ramifications for a geophysical Flood model.
Figure 8.3 is a graph of the presumed change in the land elevation near the “center” of the Laurentide and Scandinavian ice sheets. In Figure 8.3, the land gradually sinks a maximum of about 400 meters in 500 years, which is the time until glacial maximum. Because ice sheets developed so fast, the earth’s crust probably never reached isostatic equilibrium before the ice sheets began to melt. Since the ice sheets melted rapidly, isostatic recovery would be rapid at first, then would slow down considerably.
Graph of presumed isostatic rebound for the “center” of the Laurentide or Scandinavian ice sheet in a post-Flood ice age.
One other variable influencing eustasy and isostasy that has not been discussed yet is vertical, tectonic movements. Tectonic movements have been either observed, or inferred, for most areas of the world. These vertical movements can be either rapid, and associated with earthquakes (likely frequent during the ice age), or gradual subsidence, or emergence, due to an unknown process in the crust, or mantle. Consequently, it is difficult to separate this factor out of shoreline data in order to isolate the eustatic and/or isostatic component.
Gradual upward tectonic movements have been inferred for many tropical islands with coral reef terraces (Broecker et al., 1968; Veeh and Chappell, 1970). These coral-reef terraces, which are as high as 700 meters in New Guinea (Veeh and Chappell, 1970, p. 862), are most likely post-Flood. Many of these coral reefs have been related to the astronomical theory of the ice ages. This is another example of the “reinforcement syndrome,” in an effort to prove a theory (Oard, 1985, pp. 178, 179). Because of contradictions with plate tectonic models, Nunn (1986) has postulated that the tectonic uplift of tropical islands is either illusory, or slower than calculations have predicted. Investigators have not considered changes in the geoid as a possible mechanism for raising sea level to form these high coral terraces. Regardless of whether sea-level changes are due to migrating geoid anomalies, or to plain, ordinary tectonics, both mechanisms throw considerable confusion on the whole subject of eustasy and isostasy.
Origin of Biogenic Sediments
Modern investigations have revealed that carbonate ooze covers 47% of the ocean bottom, while silaceous ooze covers 15%, and days, 38% (Kennett, 1982, p. 457). Most of the surface carbonate ooze consists of the shells of foraminifera. Foraminifera are one-celled organisms that form a series of globular CaCO3 shells. They are mostly less than one millimeter in diameter. An “ooze” is usually defined as a sediment consisting of more than 30% of a particular component, in this case, foraminifera shells. The carbonate ooze below the sediment surface changes from predominantly foraminifera ooze to coccolith ooze (Roth, 1985, pp. 50, 51). Coccoliths are microscopic CaCO3 scales that cover coccolithophores-a small planktonic animal. The current rate of carbonate sedimentation is on the order of 1-3 cm/1000 years (Kennett, 1982, p. 464). Since the average depth of carbonate ooze Isaiah 200 meters (Roth, 1985, p. 51), this slow rate of deposition would require millions of years to accumulate the carbonate sediments. How can these carbonate sediments be accounted for within the Biblical time frame? The above sedimentation rate was actually inferred from steady state conditions; the CaCO3 deposition rate is balanced by the amount of new material brought into the ocean by rivers (Kennett, 1982, pp. 459, 460; Berger, 1976, p. 299). The above sedimentation rate apparently also has been confirmed recently in some areas of the ocean by observations from sediment traps (Honjo et al., 1982).
Roth (1985) has presented the creationist problem of carbonate oozes, indicating how a catastrophe may alter the deduction of a necessary long period of time. His article inspired this section, which will emphasize several of Roth’s key points, and suggest that the catastrophe of the ice age may have been responsible for most biogenic sediments. It shall focus, mainly, on foraminiferal ooze-the major constituent of the biogenic sediments. Siliceous and coccolith oozes are assumed to have been deposited by the same catastrophe, but under different regional conditions. On the other hand, evolutionists have a problem opposite to that of creationists. At the current rates of river-sediment input and supposed subduction of the sea floor, the oceans have too little sediment for the long evolutionary time scale (Roth, 1985, p. 49). In order to discuss a potential solution to this time problem, we must look at the variables that determine the carbonate sedimentation rate. There are many variables that determine this rate-most of which are poorly known (Berger, 1976). There are four major processes involved (Kennett, 1982, p. 456): 1) the supply of biogenic material, 2) the dissolution of this biogenic material, 3) the dilution of the organic material by non-biogenic sediments, and 4) the diagenetic alteration of the ooze. The third and fourth processes are deemed small in a rapid sedimentation scenario, especially in the open ocean, far away from terrigenous sediment inputs, as proposed in this section. Thus, we need only consider the rate of CaCO3 supply and dissolution. The supply of CaCO3 from near-surface zooplankton, namely foraminifera and coccolithophores, depends on the primary production of phytoplankton, which in turn depends upon sunlight in the photic zone (the upper 100 meters) and the amount of available nutrients. Davies and Gorsline (1976, pp. 13, 14) write: “The production of biogenous sediment is thus determined by the biological productivity of the ocean; this, in turn, is controlled by the available nutrient supply....” In other words, the number of foraminifera is dependent on the food chain. Sunlight, of course, is not a problem. Given optimum conditions of plentiful food, foraminifera multiply very rapidly. Roth (1985, pp. 51, 52) estimates the average depth of calcareous ooze could be produced in less than 1,000 or 2,000 years, under ideal conditions, assuming no dissolution. There is no potential biological reproduction problem. In today’s ocean, three nutrients determine the rate of growth of the phytoplankton. These nutrients are silicon, phosphorus, and nitrogen (Spencer, 1976). At present, these elements are severely depleted in the surface layer, due to biological activity and to their flux into deeper water by sinking foraminifera and coccolithophore shells. On the other hand, the water below the thermocline is overloaded with these nutrients, mostly as a result of dissolution of the zooplankton shells. Accordingly, areas of high biological activity are mainly confined to areas of oceanic upwelling, where the nutrients are transported from the deeper ocean to the surface layer. The Genesis Flood undoubtedly would supply abundant nutrients to the ocean, making foraminifera and coccolith production rapid at the end of the Flood and the beginning of post-Flood time. But the nutrients would soon be depleted in the photic zone, unless resupplied by rivers and upwelling. In a rapid ice age in which the ocean began uniformly warm, the ocean water would be rapidly mixed (see Chapter 4). This turnover would quickly replenish the nutrients in many areas of the surface layer. Broecker (1971, p. 240) states: “That the accumulation rate of CaCO3 is related to the rates of oceanic mixing has been widely recognized....”
Two other variables would act to increase biological production. Very high precipitation during the ice age would cause much greater river runoff than occurs today. As the ice sheets rapidly melted, high river runoff would continue. Consequently, nutrients would be added to the ocean more rapidly than is done by modern rivers. The warmer water would aid biological reproduction. Algae, the primary food of foraminifera, reproduce faster in warm water (Berger, 1976, pp. 291, 292). Foraminifera abundance and diversity today generally increase from the cool polar ocean to the warm tropical ocean. So there are three variables-rapid oceanic mixing, large nutrient input by rivers, and warm ocean water-that would each contribute to a large, sustained supply of foraminifera and coccoliths during the ice age. The ice-age catastrophe could produce a large supply of CaCO3, but would the carbonate be dissolved while sinking to the ocean floor? To answer this question, we must first look at the many complex variables influencing carbonate dissolution. This subject is related to the geochemical cycles for calcium and carbon dioxide. Dissolution in the deeper ocean depends upon the corrosiveness of the water, by the production of carbonic add. Kennett (1982, p. 466) lists five variables. Less dissolution in the deep water is favored by more carbonate ions, warmer temperatures, decreased water flow through the sediments, a low partial pressure of Col 2:1-23, and a reduced hydrostatic pressure. Normally, higher temperatures increase chemical reactions, but Col 2:1-23 is less soluble in warmer temperatures, so less carbonic add is formed. The last variable, of course, depends only on ocean depth, and is constant for a given point on the ocean bottom. The other four variables would be acting during the ice age to strongly suppress dissolution.
Carbonate ion content would depend upon the supply of CaCO3 from the photic zone, which would be very high during the ice age. A high supply lowers the calcite compensation depth (CCD) as a result of more carbonate ions. The CCD is the level in the ocean, above which CaCO3 rich sediments are deposited, and below which CaCO3 free sediments accumulate. Berger (1976, p. 308) writes: “Where the shell supply is low, the CCD is in the upper part of this zone [the zone of carbonate corrosion], but it migrates downward, as the supply increases.” Due to the large supply of zooplankton, the CCD would be very deep during the ice age. Bottom water temperatures during the ice age were quite warm. Rapid sedimentation would reduce the water flow through the sediments, since they would dewater faster, due to the mass of the accumulating sediments. Also, less time would be available for water flow than within the uniformitarian time frame. The fourth variable requires further discussion. Carbon dioxide reacts with water to form carbonic acid, which dissolves the shells, so less Col 2:1-23 in the water would dissolve less CaCO3 Bottom water Col 2:1-23 builds with time, due to the respiration of benthonic, or bottom-dwelling organisms, and to the oxidation of organic remains. In other words, carbon dioxide increases the older the bottom water. The more time the water spends flowing along the bottom, the more its Col 2:1-23 will increase by the above two mechanisms. This is why the calcite compensation depth is about 1,000 meters deeper in the Atlantic Ocean than in the Pacific Ocean-Atlantic deep water is young, and Pacific deep water is relatively old. During the ice age, rapid downwelling of ocean surface water in mid and high latitude would constantly replenish the deep ocean with Col 2:1-23 -depleted surface water. The deep water would have spent much less time circulating on the bottom than modern deepwater has. As a result, the amount of Col 2:1-23 in the ice-age deep water would be significantly less than it is today. On the other hand, the increased decay of organic matter due to much more biological activity, would somewhat offset the above depletion of carbon dioxide. The net effect of the first four variables would thus be decreased dissolution, and increased biogenic sediment accumulation. From these considerations, it is apparent that the rapid ice-age model presented in this monograph, has the potential to account for the depth of biogenic sediments now observed on the ocean bottom. Millions of years are not needed in this model. This example gives hope that many other geophysical features which appear to require long periods of time can be accounted for on a sound scientific basis, within the time limits indicated by the data in Gen 5:1-32; Gen 10:1-32; Gen 11:1-32. The above discussion indicates that all biogenic sediments on the ocean floor, except the most recent, were laid down in the waning stages of the Genesis Flood, and during the ice age. These sediments are dated from the Jurassic to the Pliocene, in the uniformitarian time frame. In a Flood model, sediments in this time range normally are considered to be mostly flood deposits. This may be correct for indurated sediments, but may not hold true for unconsolidated sediments. Unconsolidated ocean sediments are mostly dated by index microfossils, especially foraminifera. The organisms that produced these microfossils could easily have lived during the ice age. Some of these organisms probably became extinct as a result of crucial changes in the ocean water. Others are still living in the modern oceans.
If this is true, why aren’t modern plankton fossils found in older oceanic sediments? This brings up the complex subject of taxonomy and biostratigraphy, which is beyond the scope of this monograph and the author’s expertise. However, permit a few comments. The above two fields are based on many assumptions from historical geology. Just the classification of oceanic microorganisms is very complex with many problems (Ramsay, 1977). There is a proliferation of different names for the same organism, and much species splitting. Little is known about the biology and ecology of the modern organisms. Looking at the pictures in Ramsay’s book (1977) of the various foraminifera from various geological periods, one is impressed by how similar some of them looked to modern foraminifera.
These impressions are reinforced by an article in Origins. Tosk (1988) states how foraminifera fossils are often placed in separate biological categories-sometimes even different superfamilies-and are given a different name if they are found at different stratigraphic levels, while if discovered together, they would be considered the same species or genus. So modern foraminifera are likely represented in older sediments of the geological time scale, and are disguised by different names. Evolutionists have called this process “iterative evolution” (similar to parallel, or convergent evolution), whereby the same form supposedly evolved, repeatedly, during geological history. From a statistical point of view, iterative evolution seems incredible for a basically chance process (random mutations). It appears to be a high-sounding term, designed to cover up an embarrassing evolutionary problem. To add to the confusion, foraminifera sometimes display different forms under different ecological conditions. Some of the supposed extinct forms could be only odd varieties of present foraminifera, under critically different conditions. Some pre-Quaternary sediments, so classified according to index microfossils (Hays et al., 1969, p. 1482), are found at the sediment surface, and are probably recent sediments. In view of the many problems in using microfossils to define geological periods in the oceans, it can be concluded that practically all the biogenic ocean sediments could have been laid down at the end of the Flood, and during the ice age.