Age of solar system from radiometric dating
Trees undergo spurts in growth in the spring and summer months while becoming somewhat dormant in the fall and winter months.
When a tree is cut down, these periods are exhibited in a cross section of the trunk in the form of rings.
Simply counting the number of rings will give one a fairly good idea of the age of the tree.
This technique is based on a comparison between the measured amount of a naturally occurring radioactive element and its decay products, assuming a constant rate of decay – known as a half-life.
"Near the end you imply that low petrologic type chondrites are the most easily dated.
Actually, meteorites that formed by melting, e.g., the various types of achondrites, usually give more precise ages.
Also, because Earth formed as part of our sun’s family of planets – our solar system – scientists use radiometric dating to determine the ages of extraterrestrial objects, such as meteorites.
These are space rocks that once orbited our sun, but later entered Earth’s atmosphere and struck our world’s surface.
Thus, although "extinct", these nuclides are present in meteorites, but produced by a more recent process.