Absolute dating refers to the analysis of radioactive components in a mineral (within a rock), which provides the age at which the mineral formed (solidified) in the rock.
Such techniques are used mainly for igneous rocks that cool directly from magma, but some chemically precipitated minerals and cements in sedimentary rocks can be dated in this manner.
More common to the study of sedimentary rocks is relative age dating, where the age of a particular rock is determined relative to its position within a stratigraphic succession.
If sedimentary rocks are crosscut by datable igneous rocks, sometimes the absolute age range of deposition of the sedimentary rock can be determined.
An analysis of microorganisms in sediments and sedimentary rocks can provide a useful means of establishing rock zonations (biozones) and sometimes for determining absolute age.
Micropaleontology, biostratigraphy, and palynology are critical disciplines in the petroleum industry, for exploration and for reservoir characterization.
However, on the whole, he thought that these sources were not adequate to account for anything more than a small faction of the heat lost by the Earth.
was published, the earth was "scientifically" determined to be 100 million years old. In 1947, science firmly established that the earth was 3.4 billion years old.
Finally in 1976, it was discovered that the earth is "really" 4.6 billion years old… The answer of 25 million years deduced by Kelvin was not received favorably by geologists.
These two independent and agreeing dating methods for of the age of two primary members of the solar system formed a strong case for the correctness of his answer within the scientific community.
This just goes to show that just because independent estimates of age seem to agree with each other doesn't mean that they're correct - despite the fact that this particular argument is the very same one used to support the validity of radiometric dating today.