CompuServe Messages

>>> Both the isotope ratios and the radio active isotope decay ratio methods are completely accepted by the scientific community. Most problems and errors are understood and recognized.<< Still is crude dating when you think of the even minor leaching that water could do or heat could melt out the child of the radio active parent.>> For most radiometric dating methods, there are techniques for verifying the usefulness of the sample. One of the best methods, and the one I happen to know something about is Argon-Argon dating, which is a method of Potasium Argon dating . Using Argon-Argon in combination with single crystal methods, very accurate and reliable dates can be obtained from the proper sample, and samples can be tested to see if they are "good" independantly of the suspected age of the sample. >>Generally the "accuracy" of these age dating methods are proven by other methods of dating rocks. << What are the other ways that dating is done? << Several ways. One is to compare the dates with known or reconstructed biostratigraphy. Another is to check to see that the dates are "in order" (on top of each other in the correct age-sequence). A recent (well, ten years ago now) correlation that was very powerful in this regard is the Tulu Bor tuff in East Africa. This is one of the most widespread and extensive tuffs in the world (at least for the last 50 or so million years), and it fell over much of East Africa and the Red Sea and beyond. The tuff shows up in all sorts of geological strata, and is always found in a place that a tuff of that age "makes sense" in terms of local stratigraphy. Best of all, it is found in the Indian Ocean and Red Sea ocean cores, layered in among all those nice annual varves, in the right position! Cheers, GTL – Greg Laden, Written 06-Sep-1994 @ 21:21:19 Using: Windows NavCIS PRO 1.25