The earth is probably more than 10,000 years old.

1. Radiometric dating Con cited precisely one case of error in potassium-argon dating and claimed in was typical, and he cited on case of error in radiocarbon dating and claimed that was typical. His two claimed examples were presented by Andrew Snelling in creationist religious websites, not in peer-reviewed scientific journals. A scientist in the field of radiometry commented “the sort of nonsense Dr Snelling publishes in [creationist literature] is unlikely to be accepted in any credible scientific journal.” [15. http://www.noanswersingenesis.org.au...] I don't allege that Snelling was making up his data. The problem of lack of peer review is it denies experts the opportunity of explaining the results obtained and putting them in perspective. Other scientists have observed anomalous results for potassium-argon (K-Ar) dating of recent lava flows, and “... studies detected, in a few of the flows, deviations from atmospheric isotopic composition, most often in the form of excess 40Ar. The majority of flows, however, had no detectable excess 40Ar and thus gave correct ages as expected. Of the handful of flows that did contain excess 40Ar, only a few did so in significant amounts.” [16. http://ncse.com...] In other words that instances of error are rare. Snelling cherry-picked a rare occurrence of a known error source and presented it as typical. The error is overcome by using Ar-Ar dating with a correction for measured amounts of an argon isotope prevalent in air. [16. op cit.] The Ar-Ar method dated flows from Mt. Vesuvius occurring 1918 years ago to within 19 years. The radiocarbon dating error occurred in a unique case of wood trapped in flowing basalt, a type of sample not previously encountered. The sample should have been completely depleted of active carbon isotope, but instead was found to have a trace. The error would result with a 1% contamination of the carbon. [10, p 25] The sample was discovered by miners in the course of ordinary mining operations, not by geologists trained in the methods of preventing contamination. There might have been some other problem due to the unique nature of the sample. By not submitting the paper to peer review, Snelling protected the anomaly from logical consideration by experts. If the error is due to contamination, we would not expect it to be identical in the results from two laboratories, because there is no reason to suppose the amount of contamination would be uniform among samples. Using creationist methods we can prove that measurements of length by ruler or tape measure are useless. All we need do is discover two cases of error, and then we can dismiss all applications of the technique. Any professional carpenter will testify errors have occurred, and so we have our requisite two examples. In fact, carpenters will report that hundreds of cases of erroneous measurements have occurred. The reason that tape measures and rulers are nonetheless useful is that even though many errors have occurred they are still a very small percentage of the total number of measurements, and carpenters apply the maxim “measure twice and cut once” to check for errors. For creationists to make a legitimate case against radiometric dating, they need statistics not examples, and they do not have those statistics. Con offers no evidence that scientists just throw away dates they don't like. As I pointed out in R1, radiometric dating is cross-checked using different isotope pairs. Examples of that are given in [15 op cit]. K-Ar dating can almost always be checked with Ar-Ar dating, which depends only on the ratio of the Ar isotopes without knowing the original quantities. Uranium dating always yields two lead isotope series for cross checking. The way that Snelling detected a carbon dating error was by the inconsistency with K-Ar dating. In addition to cross-checking with alternate radiometric methods, there are independent non-radiometric dating methods used for cross-checking. We've noted varves and dendrochronology. There are also thermoluminescence dating and optically stimulated thermoluminescence dating [10. p 94], fission track dating [10. p. 115], stratigraphy (ice cores) of glaciers [10, p. 149 – 150], speleothem dating [10, p. 156], paleomagnetic dating [10, p. 214], and palaeosol dating [10, p. 228]. Any significant difference among diverse methods applied to the same sample is cause to question the data. Wikipedia. Con simply dismissed anything I referenced in Wikipedia based solely on his own authority, but he has not established himself as an expert. The Wikipedia articles cite the original sources in the scientific literature. We know that Con is familiar with looking up references from footnoted numbers, because that's how he presents his citations. Most of the Wikipedia information is also presented in [10], a basic text. If Con wanted sources restricted to free on-line clickable links, he would have had to insist upon before accepting the debate. Very few standard scientific texts are available for free online, so it makes no sense to try to impose that condition. [10] is fully described at http://tinyurl.com... 2. Sandstone and the Grand Canyon The sandstone of the Grand Canyon could not have solidified after the Canyon was formed because the walls are too steep –in some cases completely vertical-- to have stood as a sand heap, and because there is no known physical mechanism for solidification in a short time. It's the responsibility of creationists questioning established science to propose alternate mechanisms. So if the claim is that the Canyon could be cut in a matter of days, it's their responsibility to show it is possible. The reference I cited says that 90% of ice is in Antarctica, and if it melted the seas would rise by 200 feet. Con gives a Biblical account of seabeds sinking in a short time, but no scientific reference of the possibility. 3. Varves The stratification is varves cannot be produced by the turbulent mixing of floods. “During the spring and summer months, when the lake is ice-free, sediment is discharged into the lake and forms the coarser layer of the varve couplet. In winter, when the lake is frozen, deposition results solely from the settling out of fine silts and clays suspended in the water column which produces the finer component of the varve.” [10, p. 133] If the sediments were thoroughly stirred, all the coarse material would be on the bottom and all the fine material on the top. It would not be in layers. 4. Dendrochronology Con quotes my source to the effect that precise dating by dendrochronology cannot be achieved by counting rings from a single tree. That's because of the problem of missing rings due to cracking. The problem is overcome by using multiple trees from the same area and correlating the banding patterns. Con quotes a source as saying that multiple rings are a problem. Sure, but awareness of the problem allows it to be overcome and there is no indication cannot. Keep in mind that dendrochronologists produce dates to an accuracy of one year, so that even a single double ring is a matter of concern to them. Multiple rings produced by scarring are also rare, and since they are only in one specimen, the problem is completely overcome by the standard practice of using multiple specimens. The objection that no one tree is over 4800 years old is a non sequitur to the claim. It is akin to arguing that because all of the streets in the United States are not originally laid out on one map, the number and location of the streets are unknown. A composite map works fine, as does the composite of tree rings. I gave the reference for the 14,300 year date, but since our debate is about 10,000 years the 11,919 year date suffices. Of course there are many older tree specimens, but a continuous record from the present currently is only established back 14,300 years.