Dendochronologists can use this index to date accurately events and climatic conditions of the past 3000-4000 years.Varve Analysis This technique was developed by Swedish scientists in the early 20th century.
Isotopes are important to geologists because each radioactive element decays at a constant rate, which is unique to that element.
This means that if we didn't have any other way of doing absolute dating, we would as a first approximation take the age of basalt on a spreading sea floor to be the distance from the rift divided by the rate of spreading.
Now if we estimate the age of the sea floor like that, then we get a good agreement with the dates produced by radiometric methods.
Dendochronology This method of dating is based on the number, width, and density of annual growth rings of long-lived trees.
A master tree-ring index has been constructed in the southwestern United States for the Douglas fir and bristlecone pine.