Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co.
Stratigraphy uses the assumption that higher layers or strata were laid down after lower layers.
Ice cores showed the age of a military plane buried in the artic as thousands of years old.
Similarly, dendrochronology measures the tree rings in trees and assumes they represent years.
For teaching and sharing purposes, readers are advised to supplement these historic articles with more up-to-date ones suggested in the Related Articles and Further Reading below.
Before 1955, ages for the Earth based on uranium/thorium/lead ratios were generally about a billion years younger than the currently popular 4.5 billion years. old Earth is reviewed and deficiencies of the uranium/lead method are discussed.
Dating is a technique used in archeology to ascertain the age of artifacts, fossils and other items considered to be valuable by archeologists.