Anyone looking for a refutation (is that a word? Spell check liked it!)
http://www.talkorigins.org/faqs/po-halos/ The trouble is that people only see the leaflet and think someone has proven evolution/cosmology/whatever is wrong because it affirms what they want to believe.
From the end of the article...
"Gentry's entire thesis is built on a compounded set of assumptions. He is unable to demonstrate that concentric haloes in mica are caused uniquely by alpha particles resulting from the decay of polonium isotopes. His samples are not from "primordial" pieces of the Earth's original crust, but from rocks which have been extensively reworked. Finally, his hypothesis cannot accommodate the many alternative lines of evidence that demonstrate a great age for the Earth. Gentry rationalizes any evidence which contradicts his hypothesis by proposing three "singularities" - one time divine interventions - over the past 6000 years. Of course, supernatural events and processes fall outside the realm of scientific investigations to address. As with the idea of variable radioactive decay rates, once Gentry moves beyond the realm of physical laws, his arguments fail to have any scientific usefulness. If divine action is necessary to fit the halo hypothesis into some consistent model of Earth history, why waste all that time trying to argue about the origins of the haloes based on current scientific theory? This is where most Creationist arguments break down when they try to adopt the language and trappings of science. Trying to prove a religious premise is itself an act of faith, not science.
In the end, Gentry's young Earth proposal, based on years of measuring discoloration haloes, is nothing more than a high-tech version of the Creationist "Omphalos" argument. This is the late nineteenth century proposition that while God created the Earth just 6,000 years ago according to the Genesis account, He made everything appear old. Unfortunately, because Gentry has published his original work on haloes in reputable scientific journals, a number of basic geology and mineralogy text books still state that microscopic discoloration haloes in mica are the result of polonium decay.
Footnote: Omphalos means navel, and is the title of a book by Phillip Grosse. He argued that God created Adam and Eve with navels even though they had not developed in a womb."
Topic: Nullifying 'Evolution'