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101 Ways To Kill The Dinosaurs

Posted by timothy on from the russian-roulette-writ-large dept.

blank writes "Everyone knows there are many impact craters on Earth; around 170 in fact. This article from the Seattle PI points out that more than one of those impacts could have caused the extinction of the Dinosaurs. In Ukraine, scientists found that a well-known crater had been inaccurately dated - the correct date puts the impact sometime around when the Dinosaurs disappeared..."

3 of 48 comments (clear)

  1. Effects on Radioactive dating by BCGlorfindel · · Score: 2, Interesting

    Does anyone with a better knowledge of radioactive dating than me know what kind of effect these impacts have on radioactive dating methods? Would there be any, and if so on what scale? Furthermore how localized would the effects be, and finally how could/are they compensated for? The part of the article about how few craters have been accurately dated got me wondering about what kind of complications they presented for dating methods in the area around them.

    1. Re:Effects on Radioactive dating by fluffy666 · · Score: 2, Interesting

      Every dating done on a known-age volcanic rock has resulted in wildly inaccurate data. Example: Mt. St. Helens rocks were dated at (varies by sample, that alone should raise red flags about the radiometric dating concept) values ranging from 350,000 to 2,800,000 years.

      This was the dating of phenocrysts and xenoliths - rocks that soldified before the eruption. Strange you failed to mention this. Of course, if you are talking about a 500 million year old rock, a systematic error of 2 million years isn't that important.

      There are many others but that makes the point - radiometric dating is badly flawed, from K-Ar to C14 to isochrons to Ru-Sr and the rest.

      I'd like to see how you think isochrons are flawed. Radiometric dating does have independant testing - different methods can be used on the same rock, and importantly, relative dating techniques can be applied (superposition, timing of fault movement, etc.). There is no way of other physical processes systematicaly changing the dates - a neutron flux would, for instance, make some dates look much younger and others much older. Changing basic physical constants has the same effect.

      One independant technique that has been used successfully is that of sea floor dating. Since we know where - and at what temperature - sea floor crust is formed, we can calculate how old it is according to the depth using heat flow calculations. These calculated dates agree with the radiometric dates, AND dates calculated from sea floor spreading rates. So three independant methods all agree.

  2. Catastrophism vs. Gradualism by Psion · · Score: 4, Interesting

    Let's not forget that many species of dinosaurs were in decline well before the k-t event that is generally accepted as the point (65mya) when dinosaurs went extinct. Although the idea of a big rock killing all the dinosaurs is popular with geologists and catastrophists, many paleontologists still don't buy this explanation. Some even point to birds as the direct descendents of theropods and insist that dinosaurs never really went extinct in the first place.