Geology Reference
In-Depth Information
240
Unstable
Parent
Uranium
236
232
228
Radium
224
Radon
220
Polonium
216
212
Liberated helium atoms
Decay of
intermediate element
208
Stable
Daughter
Lead
204
200
80
82
84
86
88
90
92
94
Atomic number
Uranium, the geologist's clock.
The decay chain of uranium (238) to lead (206) via radium, radon, polonium and other intermediate elements.
Each radioactive decay to the left is accompanied by the release of helium.
