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Non-Radiometric Dating

These methods have been used to provide independent lower limits for the age of the Earth.  Also, by radiometrically dating these items we can cross-check the accuracy of radiometric dating.  This has shown that radiometric dating is in general extremely accurate.

Tree Rings (dendrochronology)

Trees generate a ring for each year of growth.  Counting these rings gives an age for the tree.  This has been done for the the bristlecone pine trees, which grow very slowly and live up to 6,000 years.  These trees grow in a very dry region near the California-Nevada border. Dead trees in this dry climate take many thousands of years to decay. The tree ring patterns of living and dead trees can be compared and then linked together into a continuous history or tree rings.

Using this method the continuous rings have been dated back to 11,800 years ago.

• http://www.asa3.org/ASA/resources/Wiens.html
• http://www.talkorigins.org/indexcc/CC/CC332_1.html
• http://www.apologeticspress.org/articles/2019
• How Growth Rings Form
• Dating Methods in Archaeology

Ice Cores

A continuous count of ice core layers exists back as far as 160,000 years.    Volcanic eruptions and other major geologic events can be used to correlated between ice cores. Historical eruptions, such as Vesuvius can used to verify the accuracy layer dating.

• http://www.asa3.org/ASA/resources/Wiens.html#page.%2016

Coral Reefs

Corals deposit daily growth bands  These can be used to tell how many days there were in a year when the coral was growing.  Modern corals have about 365 day-bands per year.  By measuring the rate at which Earth's rotation is slowing, it can be determined how many days were in a year in times past.  This method predicts that 400 million years ago each year was about 400 days.  Corals that grew in formations radiometrically dated as 400 million years old, show about  400 day-bands per year.

• http://www.jwoolfden.com/rad_dat.html#Checks
• http://www.asa3.org/ASA/resources/Wiens.html#page.%2016

Varves

Varves are variations in sedimentary layers deposited underwater caused by the change in the seasons.  These are useful in deep lakes where the bottom layer is not disturbed.  Varves have been measured going back to about 35,000 years.

• http://www.asa3.org/ASA/resources/Wiens.html#Page%2017

Green River Shale

• http://www.atheists.org/evolution/morrisdebate.html

Lake Suigetsu Algae

Tiny one-celled algae bloom each year in Lake Suigetsu, Japan.  When they die, they sink to the bottom of the lake creating a thin, white layer.  This layer is then covered with the dark clay sediments that settle to the bottom the rest of the year.  This forms annual alternating light and dark layers.  These number up to 45,000 layers representing 45,000 years.  This dates have been verified against carbon-14 dating, giving the same age.  The fact that carbon-14 dating and algae layering produce the same age is good evidence that these methods are accurate, since the factors that affect one don't affect the other.

• http://www.religioustolerance.org//oldearth.htm
• http://home.entouch.net/dmd/suigetsu.htm
• http://www.accuracyingenesis.com/varves.html

See also
Discussion of various radiometric and non-radiometric dating methods

• http://hometown.aol.com/darwinpage/datingmethods.htm