Layers of sediment underlying some lakes can be read like rings in a tree. These layers called varves (alternating layers of sediments and/or organic material) and the precise counting of one that represent annual layers have been used to test and calibrate radiocarbon dating methods. A few weeks ago there was a report on additional work to improve the accuracy of the radiocarbon clock. This included more detailed tests of the varves from a well studied lake in Japan, Lake Suigetsu. The full open access article from Science can be found here with a summary from Nature magazine here. I’ve talked about varves in the past and hundreds of articles, books and blogs have discussed the use of varves for determining chronological age. For many years varves have been used to challenge creation science and its assumptions that scientific evidence points to a young earth. I feel like it should be unnecessary to review the evidence yet again as it has been repeated over and over. But, varves represent one of the most compelling reasons to believe that the world is more than 6000 years old and the response by creationists is illustrative of just how weak creation science is as a predictive and useful scientific theory. Below I briefly review this well-studied varve deposit in Japan and show how creationists have reacted to this data.
Why is Lake Suigetsu a good place to examine varves?
Lake Suigetsu is one of 5 lakes that were formed from volcanic eruptions. The reason this lake was targeted for study is because scientists are fully aware of the problems of assigning layers of sediments to the equivalent of annual rings and this lake has all the features that one could hope to find in a location that will likely avoid many of those problems. Annual varves are thought to be the result of different compositions of sediments and organic material in the spring/summer vs the fall/winter. To avoid the problem of false layers produced in many places by floods or inconsistent seasonality a location that is protected and exhibits a strong season signal is best. Lake Suigetsu fits those requirements. For example, the Hasu River enters Lake Mikata where the sediments suspended in the river, even during a large flood, will fall out. Water then flows through a narrow but shallow channel into Lake Suigetsu which is surrounded by high cliffs on all sides and has almost no input of water from the surrounding area save a very few very small creeks. The result of this is that the waters of Lake Suigetsu have very little suspended sediment and the surrounding walls limit the wind on its surface so the waters are not disrupted. Thus the center of the lake is extremely stable and unlikely to be disturbed by floods, large storms, etc… Input to the sediment on the bottom mostly comes from material falling into the lake from the air (leaves, pollen, volcanic ash, dust) or from differential growth of organisms (algae) over the year. What is amazing about most of the varves of Lake Suigetsu is that even microscopically the varves formed 1000 years ago look the same as those formed 40,000 years ago. Even as one moves in the core from varves formed in the past several hundred years when the climate was known from this region and varves were formed one each year back to 10s of thousands of years ago, the varves have the same characteristics. This provides even more confidence that the varves represent annual years and that the climatic influences on this lake in the past have been very similar to those of the present.
How do the varves form in this lake?
There is strong seasonality in this region with summer and winter monsoons. The high precipitation in the winter along with cold/freezing water and decaying plant material and algae results in deposition of both different organics (eg. pollen in spring vs lack of pollen in winter) in summer vs winter but higher sediments during the winter. The result is alternating bands of material. These layers are very very thin because in the very middle of this lake, were the cores were taken, the total amount of material that settles to the bottom of the lake amounts to less than 1mm per year. I want to stress here that climatologist and biogeochemists has spent considerable time documenting the layers in multiple cores in this lake. They have counted layers by multiple methods
including by eye and by computer assisted techniques and more recently by various scans of the cores using other methods of imaging which highlight differences in organic content which can accentuate the winter season layers making the reads more accurate. Careful and independent counts of the annual layers have been performed and more than 800 samples of leaves and other organic content (pollen grains etc..) have been selected from the cores for carbon 14 dating. In addition, 40Argon/39Argon dating has been performed on tephra (ash) layers found in the cores sections (see picture to the right for an example) and two other types of dating methods have been performed on the cores (please see the Science article for details, additional papers about varves and chronology around the world can be found in this issue of Quaternary Science Reviews). The multiple cores from the sediments in this lake have been examined by many scientists overt the past 20 years. Over that time the quality of the data has improved as assumptions about varves have been tested with new techniques and new forms of dating allow further independent dating methods have increased confidence in the varve counts.
What are the data derived from Lake Suigetsu?
Initial studies in the early 1990s found a tight correlation between varve count and C14 dates of organics in the layers going back 40,000 varve years. There is obviously a correlation with age and depth of the column as well (see figure to the right). The most recent analysis reported in Science and detailed further in several other papers published or in press today are now taking the varve counts back to 60,000 years. Several ash layers have been dated with other radiometric dating techniques and they show dates that fall on the line of varve counts. Over 800 samples of organic material have been C14 dated and each of those has been sent to at least two (sometimes 3!) radiocarbon labs for independent verification of the C14 dates. Incredible rigor in selecting samples for C14 dates and blind testing at multiple labs has been done because one of the primary goals of the Suigetsu varve counting group is to test and calibrate the C14 clock.
Consider also that there are more than 30 visible ash layers which form discrete almost pure glass crystal layers that lie between varve layers. These would have formed from airborne ash from volcanoes in the area. That ash would have fallen directly into the lake and settle quickly to the bottom. Had this ash been brought in by the river it would have been mixed with other sediments. These ash layers attest to the fact that this lake had very clear undisturbed waters during the whole period that these varves formed. In addition to the 30 visible layers there are at least 100 additional ash deposits that are so fine that they can only be identified by microscope. These would represent ash from very distant or small volcanic explosions that brought a very small amount of ash fallout to the lake. The advantage of these ash deposits is that some of them can also be radiometrically dated and those dates compared to the varve/layer counts. When this is done an ash layer found at varve count 9000 is found to have a radiometric date of around 9000 years. This represents yet another independent verification that both the varve counts accurately reflect the passage of time in the forms of annual layers.
Over the years there have been multiple cores taken from the lake which have had their varve layers counted multiple independent times by multiple methods. C14 dating has been performed by multiple groups over a period of 20 years and other forms of dating have continued to confirm that the varves in this lake represent individual years. When this data is combined with data from other locations and tree ring data a very compelling picture of a consistent chronology extending back a minimum of 50,000 years appears. Below is a composite figure showing the relationship of tree rings, varves and C14 dates compiled from multiple studies from different locations in the world. What we see is an amazing correlation of these data points.
Creation Science response to the Lake Suigetsu varve chronology
Varve counting chronologies have been used as a challenge to the young earth creationists view of earth history for 30 years. Given that time frame there is remarkably little literature from creation science on varves and their interpretation. Only one actual experiment has actually been performed to attempt to recreate something that looks like varves and that was done with sediments only rather than any organic material on which most of the important varve chronologies are based. Dr. John Reed, who has a PhD in geology, provides the most typical response to varves in a paper entitled, Toppling the Timescale Part III: Madness in the Methods in the Creation Research Quartarly in Summer of 2008. Despite their significance to chronologies and C14 dating there is only this one mention of varves in this paper:
“Like varves or ice layers, geologists simplistically assume that the target sediments were deposited slowly, uniformly, and in response to regular climatic variables. Remove those assumptions and the whole theory crumbles, as has been shown for both ice layers (Oard, 2005) and varves (Oard, in press).”
Oard simply tries to argue that rapid sedimentation can cause the appearance of varve like layers which could be mistaken as annual years when they really represent catastrophic events. He also reports in several papers examples of lakes and other fossils varve sites (ancient preserved lakes with varved rock) where there is evidence of multiple varves produced in a single year. The strategy then is to suggest either implicitly or explicitly that because exceptions can be found to varves representing individual years that all reports of varves should be discredited. Dr. Reed takes the same approach and has provided responses to varve arguments in numerous papers. His responses though include nothing more than accusations that the assumptions are incorrect and that scientists are unwilling to consider alternative means by which these tens of thousands of layers could have been formed. Has Dr. Reed considered what he would do if he can’t remove any of those assumptions (slow, uniform, and in response to regular climatic variables)? The Lake Suigetsu cores were examined because exactly because they are in a location that provides the optimal conditions for those three assumptions NOT to be violated because the scientists doing the research are perfectly aware of these assumptions.
A more recent example of the creation science response to the Lake Suigetsu varves in particular can be found in an article “Long-age geology or Genesis” by John Reed published on CMI’s web site. Dr. Reed writes a short response to an article written by a group of eight Christian PhD geologists who wrote an article entitled “PCA Geologists on the Age of the Earth” where they examined several evidences of the age of the earth and conclude that the evidence strongly points to an ancient earth. Dr. Reed provides a quick rebuttal to their arguments including the varves from Lake Suigetsu:
“The first example is the “varved” (finely layered) sediments of Lake Suigetsu in Japan. Apparently, the varves present a “record” of 100,000 years, reinforced by C14 dating and dendrochronology. And of course, once the lake sediments have blown away the creationist position, the authors can then point to the rock record beneath the lake as “proving” millions of years.
Like any other interpretation, this one is a combination of data and assumptions. There is no attempt to consider a serious Flood alternative; it is simply a matter of PhD condescension towards the ignorant peasants who give the elite accommodationists a bad name in the eyes of the world. If the sediments are annual varves … if C14 dating is accurate … if dendrochronology is accurate … etc. If, if, if. Unfortunately, none of these can be demonstrated, as shown by the links above. Another good resource is Rock Solid Answers, where Mike Oard has a good chapter on varves.”
This is a “short” response by Dr. Reed. However, he also produced a longer more technical line by line response to the same article. I don’t really need to review that response because it isn’t much more technical. He simply throws out the same doubts about c14 dating and varves and claims that these scientists haven’t been willing to consider alternatives. But what alternatives does Dr. Reed provide? He asserts that links to other articles provide demonstrations that varves and c14 doesn’t work. But even if they didn’t work that isn’t an alternative answer and his like to an article that varves are not valid is to a paper by Oard that doesn’t have anything to do with the Suigetsu varves or varves of the same kind at all. I’ve read all of Oards’ refutations of varves and most have little to do with reality but are hand-wavy assertions that because one lake has layers that aren’t annual years that this casts doubt on all other layers in other lakes around the world. Does he really think that scientists are so ignorant of their assumptions and are unaware of variables that can cause varves to be unreliable. Scientists have found many varve records to be unreliable chronological markers precisely because they DO understand that there are assumptions that must be met to produce reliable inferences.
Dr. Reed has produced a more technical response to the same article in support of an old earth. In that article he provides no more evidence that the Suigetsu varves are invalid than he does in the first quote from 2008. I find it very difficult to find much charitable to say about Dr. Reeds responses and attitudes. Of course he is upset that his beliefs about a young earth are being challenged but he is supposed to be a PhD geologists capable of critically analyzing and demonstrating the faults in interpretations of old earth geology. What we get instead is nothing but name-calling rhetoric. He faults scientists including other Christians for not considering the alternatives and yet provides no other alternative himself other than the Flood which isn’t a specific alternative hypothesis. He and others provide no alternative to the specific data of sites such as Lake Suigetsu. I have spent a couple of hours reading the original literature and examining the data that was reported. These authors provide extensive details about why they believe the varves to represent annual layers and not just individual events layers as are seen in other lakes in other parts of the world. What has Dr. Reed done to respond to the Christian geologists who have used the Lake Suigetsu varves as evidence of an old earth? Apparently he hasn’t done them the courtesy of reading the original literature himself but has just dredged up the usual responses which generically apply to some other varved sediments yet he can claim confidently they must be wrong! He doesn’t address the specific environment in which these varves are deposited. He provides no alternative geological explanation for this specific site at all. For example, does he or Oard address how very discrete bands of ash can be found between 10s of thousands of fine bands they claim were formed in a matter of months or just a few years? I haven’t even seen Reed acknowledge to his audience that such bands of ash exist in these varved layers! His strategy and that of other creation scientists seem to be to simply proclaim as loudly, as boldly and as confidently as they can that there is an alternative and to make fun of scientists for being unable to see the real truth. It’s all preaching to the choir rather than providing an actual response to the challenge. Given that they have had 30 years to come up with a response the fact that they are still just trying to tell the choir what they want to hear suggest that they have no real response. Rather, what we are seeing here is reminiscent of the response that I reported in my post: Having Faith in Flood Geology: Dogmatic Assertions of Evidence.