radiohalos, and the particles that they send out have different energies (MeV).
We can be certain that no other radioactive element appeared at the center of the polonium radiohalos. If any other elements had been there, such as uranium or radon, they would have formed other rings as they decayed.
So where did the polonium atoms come from?
The best possible answer is that the polonium traveled from a nearby source where uranium atoms were decaying. Is there such a nearby uranium source? Absolutely! The same flakes that host the polonium radiohalos usually contain uranium radiohalos, usually less than a fraction of an inch from polonium radiohalos (Figure 6).
The source of uranium radiohalos still survives in granite rocks: tiny zircon crystals. But geologists are mystified because the source of polonium radiohalos is missing. The answer lies only a tiny way up the biotite sheet . . . the zircons!
Biotite flakes often have numerous polonium radiohalos, in addition to uranium radiohalos.
FIGURE 7—Diagram of a cross-section through a biotite flake where radiohalos are found. The uranium-238 in the zircon crystal generated the uranium-238 radiohalo. Water flowing past the crystal carried decaying atoms along the same sheet to a nearby location, where a polonium-210 radiohalo developed. Nothing remains at the center of this radiohalo, however, because it dissolved quickly.
Yet under normal conditions, like those we see in the earth today, that migration would be impossible. To understand the magnitude of the problem, you need to understand how many polonium atoms had to migrate and how quickly they had to travel.
Scientists have estimated that each radiohalo’s discoloration initially develops after 100 million alpha-particles have been emitted from its center. It does not become dark until 500 million particles, and it does not become very dark until one billion alpha particles have been ejected.3 This means that each polonium radiohalo needs at least 500 million polonium atoms. And many polonium radiohalos often appear in the same specimen, so many billions of polonium atoms had to move into position to explain the radiohalos we see.
Then there is the problem of how fast they must be moved. Polonium-214 atoms decay so quickly they are gone in the blink of an eye! Polonium-218 has a half-life (decay rate) of only 3.1 minutes, while polonium-214 decays in 164 microseconds!4 By comparison polonium-210 atoms are long-lived, with a half-life of 138 days. What unusual forces could have carried so many atoms away from the uranium source so quickly?
Another possibility is to move another element in the uranium-238 decay chain that appears before polonium. For example, the element immediately before the polonium-218, polonium-214, polonium-210 sequence is radon-222. If radon-222 moved into place, then the polonium would not have to be transported. But this presents two problems. First, the travel time is still short: the half-life of radon-222 is only 3.8 days. The radon would still have to be transported from the zircons to the polonium halo sites in only days.
Second, we don’t find a radon-222 decay halo in the polonium radiohalos. Somehow the polonium had to separate from the radon-222 and then concentrate in what would become the polonium radiohalo centers. The location of radiohalos and the different chemical properties of radon and polonium suggest a solution to these problems.
When uranium and polonium radiohalos are observed under the microscope, their radiocenters are actually on the same sheet.5 As explained in the first article, radiohalos are found in the dark flecks within granites, called biotite. These biotite flakes consist of layers and layers of crystal sheets, which can be pulled apart and examined under a microscope.
Water can easily travel down the spaces between these sheets (Figure 7). Changes in the biotite’s color are often evidence that water has seeped between the sheets. That’s the key to the creationist explanation for polonium radiohalos.
When granites crystallize and are cooling, hot waters are left ove