Hobbies And Interests
Dendrochronology
Dendrochronology is a type of absolute dating centered on the annual ring growth characteristic in trees. The rings are affected by factors like weather and age, which determines the thickness in their appearance. By using a horizontal cross-section cut, the trees can be thoroughly studied. One variation on this method is the cross-dating technique, which matches the characteristics of a specific ring to other samples from the same area. Scientists study the varying patterns, and associate reasons, like drought, for ring thinness or thickness.
Stratigraphy
As a proven method of analyzing earth layers, or strata, stratigraphy effectively determines age. When layers of earthly material accrue on an object, the oldest sediment is at the bottom. Scientists determine the object's position between the layers to establish its age. Accurate dating, however, is difficult to authenticate in cases where man or nature has disturbed the strata.
Radiometric
The absolute dating method called radiometric utilizes radioactive decay. It focuses on carbon-14, a radioactive material that is absorbed by living organisms. Carbon-14 later decays, forming nitrogen. When the organism dies, the carbon-14 ratio begins to decrease. Establishing the half-life of the material helps to reveal the organism's age. The half life of C-14 is 5,730 to 5,740 years; that shortened span of time means it cannot date very old fossils, however.
Potassium-Argon
Potassium-argon dating successfully dates very aged archaeological materials. Geologists have used it to date rocks as old as 4 billion years. The method is based on the knowledge that some of the radioactive isotope of potassium decays, becoming argon-40. Comparisons are then made between the proportion of K-40 and Ar-40 to zero in on an age of origination.
Fission Track
This method involves knowledge of the sample's uranium content through the inspection of a polished piece of material to determine the density of the track markings left in it by the spontaneous fission of uranium-238 impurities. It is acomplished by placing a plastic film over the polished material.