One of the more recent evidences was discovered by the RATE group (a group of scientists from various creationist organizations). Following is a quote.
"There is now powerful independent confirmatory evidence that at least one episode of drastically accelerated decay has indeed been the case, building on the work of Dr Robert Gentry on helium retention in zircons. The landmark RATE paper1, though technical, can be summarized as follows:
When uranium decays to lead, a by-product of this process is the formation of helium, a very light, inert gas which readily escapes from rock.
Certain crystals called zircons, obtained from drilling into very deep granites, contain uranium which has partly decayed into lead.
By measuring the amount of uranium and radiogenic lead in these crystals, one can calculate that, if the decay rate has been constant, about 1.5 billion years must have passed. (This is consistent with the geologic age assigned to the granites in which these zircons are found.)
There is a significant amount of helium from that 1.5 billion years of decay still inside the zircons. This is at first glance surprising for long-agers, because of the ease with which one would expect helium (with its tiny, light, unreactive atoms) to escape from the spaces within the crystal structure. There should surely be hardly any left, because with such a slow buildup, it should be seeping out continually and not accumulating.
Drawing any conclusions from the above depends, of course, on actually measuring the rate at which helium leaks out of zircons. This is what one of the RATE papers reports on. The samples were sent (without any hint that it was a creationist project) to a world-class expert to measure these rates. The consistent answer: the helium does indeed seep out quickly over a wide range of temperatures. In fact, the results show that because of all the helium still in the zircons, these crystals (and since this is Precambrian basement granite, by implication the whole earth) could not be older than between 4,000 and 14,000 years. In other words, in only a few thousand years, 1.5 billion years worth (at todays rates) of radioactive decay has taken place. Interestingly, the data have since been refined and updated to give a date of 5680 (+/- 2000) years."
TheAman_1