So in order to date most older fossils, scientists look for layers of igneous rock or volcanic ash above and below the fossil. "
http://evolution.ber...micclocks.shtml
"To determine the ages of these specimens, scientists need an isotope with a very long half-life. Some of the isotopes used for this purpose are uranium-238, uranium-235 and potassium-40, each of which has a half-life of more than a million years.
Unfortunately, these elements don't exist in dinosaur fossils themselves. Each of them typically exists inigneous rock, or rock made from cooled magma. Fossils, however, form in sedimentary rock -- sediment quickly covers a dinosaur's body, and the sediment and the bones gradually turn into rock. But this sediment doesn't typically include the necessary isotopes in measurable amounts. Fossils can't form in the igneous rock that usually does contain the isotopes. The extreme temperatures of the magma would just destroy the bones.
So to determine the age of sedimentary rock layers, researchers first have to find neighboring layers of Earth that include igneous rock, such as volcanic ash. These layers are like bookends -- they give a beginning and an end to the period of time when the sedimentary rock formed. By using radiometric dating to determine the age of igneous brackets, researchers can accurately determine the age of the sedimentary layers between them."
http://science.howst...r-bone-age1.htm
Ok so essentially, they date fossils by igneous rock and volcanic ash nearby in corresponding layers. Not a problem. The problem is this:
"The radioactive potassium-argon dating method has been demonstrated to fail on 1949, 1954, and 1975 lava flows at Mt Ngauruhoe, New Zealand, in spite of the quality of the laboratory’s K–Ar analytical work. Argon gas, brought up from deep inside the earth within the molten rock, was already present in the lavas when they cooled. We know the true ages of the rocks because they were observed to form less than 50 years ago. Yet they yield ‘ages’ up to 3.5 million years which are thus false."
http://creation.com/...-dating-failure
The Uinkaret Plateau samples came from lava flows on the plateau at the top of the Grand Canyon. Some of these lava flows actually flow down into the canyon, so the eruption must have occurred after the canyon was formed. This lava is some of the youngest rock in the Grand Canyon. The radiometric ages for this formation go from 10,000 years (the 0.01 K-Ar date in the upper left section of the table) to 2.81 billion years (the Pb-Pb isochron date). Rubidium-strontium dates all agree that the rocks are about 1.3 billion years old, which would make them pre-Cambrian rocks, not modern Quaternary rocks (which they obviously are).
http://www.scienceag....org/v4i11f.htm
Native American artifacts found within Uinkaret Plateau lava flows (slides 20-23).
http://bara.arizona....magesonAZSt.pdf
So we have volcanic rocks being used to date fossils, measuring millions of years worth of age, when observation tells us that lava can show radiometric ages of millions of years when it is 50 years old. We also see artifacts that are determined to be 3000-1000 years old in lava that measures millions of years old.
This is a dating fail more awkward than forgetting to put on deodorant...
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"Fossils are generally found in sedimentary rock—not igneous rock. Sedimentary rocks can be dated using radioactive carbon, but because carbon decays relatively quickly, this only works for rocks younger than about 50 thousand years.
So in order to date most older fossils, scientists look for layers of igneous rock or volcanic ash above and below the fossil. "
http://evolution.ber...micclocks.shtml
Real Science Friday reported on rock solid data showing radiometric carbon found in dinosaur bones, and refuted the idea that the results could have been explained away by contamination or neutron capture:
http://kgov.com/dating-a-dinosaur
Yet another awkward dating fail... It takes awhile for refutations of old assumptions to be verified and passed around. Meanwhile, popular culture moguls stand by and take pot-shots at creationists out of ignorance.
Cheers.