Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Halo
Name: Rachel
Status: student
Age: 20s
Location: N/A
Country: N/A
Date: 2000-2001

How would you explain, according to evolutionary theory, the existence of many millions of atomic decay halos found in granite that begin their decay sequence with polonium? My understanding is that polonium is not a naturally occurring element. The phenomenon of finding decay halos beginning with polonium in solid granite extending over 20 feet into the earth would be analogous to finding Alka-Selzer bubbles preserved in an slowly-frozen glass of solid ice--the granite should have taken too long to cool for there to be any polonium remaining to decay, especially in the quantities that have been found. The granite would have to have been formed instantaneously. So how did this happen?

Aah, polonium halos. Another favorite creationist argument. The halos in some rocks that supposedly arise from the rapid decay of many polonium atoms in the same place supposedly show that the rocks in which they formed had to solidify in three minutes or less, proving that the earth was created in an instant.

Well, it's not so simple as that. You can find a much more detailed explanation at the website; I'll give you a brief version. Polonium is a decay product of radon, which is formed in several steps from the radioactive decay of uranium. All of these polonium halos have been found in uranium-rich rocks, so there is plenty of raw material fom making polonium available over geologic time. The key thing about radon is that it is a gas, and thus can be fairly mobile in rock. Say, for instance, that a uranium-bearing rock has a small crack in it. Over hundreds of millions of years, radon atoms that form from uranium decay diffuse to the crack, migrate along the crack, and then are trapped at the end of the crack. The radon decays to polonium, which settles out on the wall of the crack. The polonium atom then decays, leaving a trail of damage in the rock. As large numbers of polonium atoms are deposited in the same spot, the trails of radiation damage form a sphere - the "polonium halo." So it is not necessarily true that "the granite would have to have been formed instantaneously."

Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois

Click here to return to the Physics Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory