This post summarises a 2012 blog entry by Christian biologist Joel Duff: 'Lake Suigetsu and the 60,000 Year Varve Chronology' [footnote 1], as well as drawing on information from other sources.
Over the past 20 years climatologists and biogeochemists have documented the varve layers from multiple sediment cores taken from Lake Suigetsu in Japan. Suigetsu is targeted for study because:
- it has high cliffs on all sides, which protect the lake from wind, floods and storms
- it has a single river inflow via another lake, so only the finest sediment enters the lake
- it experiences strong seasonal differences, which produce alternating bands of material in its varve layers (such as pollen in spring but not in winter)
- water at the very bottom of the lake is anoxic (deoxygenated), which prevents the growth of organisms on the lake bed.
Suigetsu's varve layers (over 100,000 of them) are ideal because they have the same characteristics – layers from the past several hundred years (when the climate was known) have the same kind of material as those counted to 2,000 or 20,000 years ago.
There are more than 30 visible ash layers that form discrete layers between Suigetsu's varve layers. This ash fell into the lake after volcanic eruptions in the area (had it been brought in by the river it would have mixed with the other sediments). There are also over 100 ash deposits so fine they can only be identified by microscope; this ash is from very distant or small volcanic eruptions. The presence of these ash layers show the lake had undisturbed waters when the varves formed.
Additionally, because volcanic eruptions occur over relatively short periods of time, scientists can compare ash from the same eruption at different locations and use this to produce time-equivalent markers for different places. Some volcanic deposits can also be used as a direct dating tool: for example, deposits rich in sanidine crystals can be independently dated by the 'argon/argon (40Ar/39Ar)' method. Ash in the Suigetsu varves is too fine or crystal-poor to be directly dated using the 40Ar/39Ar technique, but it can be matched to 40AR/39Ar dates for time-equivalent deposits elsewhere.
More than 800 samples of organic material from Suigetsu's varves have been carbon-14 dated. This dating has found a tight correlation between the varve count and the carbon-14 dates for the organic material. The Suigetsu varve chronology has also been cross-checked with age data for stalagmites (Bahamas GB89-25-3 and Hulu Cave H82), the European Late Glacial Pine record, the Lake Soppensee varve chronology and sediment cores from the Cariaco Basin and the Iberian Margin. When the Suigetsu data is combined with data from other locations, 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 measured carbon-14, compiled from multiple studies from different locations in the world.
Young-Earth creationists' response to the Suigetsu varves
There is relatively little literature from young-Earth creationists on varves and their interpretation. Sedimentologist Guy Berthault appears to be the only young-Earth creationist to have conducted original experiments in this field and therefore is widely cited by others (Sarfati cites him on page 112 of The Greatest Hoax on Earth). However, Berthault's experiments used only sediments and not any organic material (on which most of the important varve chronologies are based).
Puzzlingly, the focus of Sarfati's discussion of varves in The Greatest Hoax on Earth is the work of Swedish geologist Gerard De Geer. This is puzzling because De Geer conducted his work in the late 1800s and early 1900s, and problems in his work have been well documented and corrected by other geologists since the 1930s. Sarfati cites only one reference in his discussion on varves: a 20-year-old paper by young-Earth meteorologist Michael Oard. Oard argues that varves do not support an old Earth because of two problems: first, rapid sedimentation from catastrophic events can cause the appearance of varve-like layers, which could be mistaken as annual years; second, there are specific examples of lakes and fossilised varve sites (ancient preserved lakes with varved rock) where there is evidence of multiple varves being produced in a single year. Because of these problems, Oard implies any varve chronology claiming an age beyond Noah's flood should be discredited. However, neither of Oard's problems apply to the Suigetsu varves. The presence of multiple, discrete ash layers show the varves were not formed by rapid sedimentation. And Lake Suigetsu is not one of the sites with evidence of non-annual layers.
What Oard (and Sarfati) fail to tell their readers is that geologists know that not all varves are deposited in annual cycles, and they have identified the mechamisms by which non-annual layers are deposited. Oard's implication is that geologists are either ignorant of their assumptions and unaware of variables that can cause varves to be unreliable, or they are being deliberately deceptive. However, geologists have been able to identify the varve records that are unreliable as chronological markers precisely because they understand the assumptions and variables involved.
In recent years there have been a few attempts by young-Earth creationists to address the Suigetsu varves. Oard mentions them in his chapter on varves in a young-Earth creationist book. He only does so briefly, because "there is very little literature on these varves in English, and so it is difficult to analyse them". This doesn't stop Oard from offering a few very general and unsupported conjectures about how the Suigetsu varve chronology could be incorrect (such as: varves in other places can form several layers a year; after Noah's flood there was a great Ice Age that "probably" produced more dust, which "could have" produced more layers in lakes such as Suigetsu; and measurements of carbon-14 are unreliable because Noah's flood altered the ratio of carbon-14 to carbon-12).
The Suigetsu varves are also mentioned in two articles written by young-Earth geologist John Reed: a short article on the website of Creation Ministries International (CMI) and a more detailed version on the website of CMI's rival, Answers in Genesis. Reed's articles counter an article written by eight Christian geologists that presents evidence of an ancient Earth, including the Suigetsu varves. Reed's argument is little more than: there have been problems with some other varve chronologies; there was a problem with one chronology specific to Suigetsu (a problem correlating the varves with carbon-14 dating past 31,000 years); and, ultimately "none of these secular publications can demonstrate a date in excess of 100,000 years".
Young-Earth creationists fail to provide an alternative geological explanation for the specific data of Lake Suigetsu (particularly the discrete ash layers from volcanic eruptions). Instead, they tend to rely on general claims about natural processes having been altered by Noah's flood. But even these claims are problematic. As Christian geologists Gregg Davidson and Kurt Wolgemuth put it:
For those who wish to argue that natural processes could have been vastly different during the Flood, there are at least two replies. First, under such a scenario, there is no point in Flood Geology studies any more than in normal studies, for nothing could be gained by the study of unknowable processes. A more important question, however, would be to ask why God would alter natural processes just to make Flood sediments look like they are not flood sediments. What would the purpose be?
 Joel Duff, 'Lake Suigetsu and the 60,000 Year Varve Chronology' (12 November 2012) http://thenaturalhistorian.
 Victoria Smith, et al, 'Towards establishing precise 40Ar/38Ar chronologies for Late Pleistocene palaeoclimate archives: an example from the Lake Suigetsu (Japan) sedimentary record', Quaternary Science Reviews, Vol 30 (2011), pp 2845-2850.
 Christopher Ramsey, et al, 'A complete terrestrial radiocarbon record for 11.2 to 52.8 kyr B.P.', Science, Vol 338, No 6105 (2012), pp 370-4; available online at: http://cs6101.vk.me/
 Source: Gregg Davidson and Ken Wolgemuth, 'Christian Geologists on Noah's Flood: Biblical and Scientific Shortcomings of Flood Geology' (2010) http://www.solidrocklectures.
 Gary Berthault, 'Experiments on lamination of sediments, resulting from a periodic graded-bedding subsequent to deposition – a contribution to the explanation of lamination of various sediments and sedimentary rocks', Compte Rendus Académie des Sciences, Vol 303, Série II, No 17 (1986), pp 1569–1574; Gary Berthault, 'Sedimentation of a heterogranular mixture: experimental lamination in still and running water', Compte Rendus Acadèmie Des Sciences, Vol 306, Sèrie II (1988), pp 717–724.
 See, for example: Barbara Wohlfarth, Svante Bjorck and Goran Possnert, 'The Swedish time scale: a potential calibration tool for the radiocarbon time scale during the late Weichselian', Radiocarbon, Vol 37, No 2 (1995), pp 347-59; online at: https://journals.uair.arizona.
 Michael Oard, 'Varves – the first 'absolute' chronology part I – historical development and the question of annual deposition', Creation Research Society Quarterly, Vol 29, No 2 (1992), pp 72-80.
 See, for example: A Lambert and K Hsu, 'Non-annual cycles of varve-like sedimentation in Walensee, Switzerland', Sedimentology, Vol 26 (1979), pp 453-61
 Michael Oard, 'Do varves contradict biblical history?', in M Oard and J Reed (editors), Rock Solid Answers, Green Forest: Master Books, p 131.
 John Reed, 'Long-age geology or Genesis' (20 July 2010) http://creation.com/refuting-
 John Reed, 'A Response to the Old-Earth Advocacy of Campbell et al., PCA Geologists on the Antiquity of the Earth' (18 August 2010) http://www.answersingenesis.
 David Campbell, et al, 'PCA Geologists on the Antiquity of the Earth', Modern Reformation, Vol 19, No 3 (2010), pp 6-9; available online at: http://www.modernreformation.
 Reed, 'A Response to the Old-Earth Advocacy of Campbell et al'.
 Davidson and Wolgemuth, 'Christian Geologists on Noah's Flood', p 5.