Disadvantages of rubidium strontium dating
The basic science behind this method is that calcareous shell material incorporates the two strontium isotopes in the same ratio that occurs in seawater at the time the organism was alive.At different times in Earth's history, the relative abundance of these two isotopes in seawater gradually changed through time (such as during the Permian, the Late Cretaceous, and parts of the Tertiary).In addition to the chemical and physical characteristics of volcanic ash, select igneous minerals in the ash can be used for absolute dating (discussed below).
A relative age is the age of a fossil organism, rock, or geologic feature or event defined relative to other organisms, rocks, or features or events rather than in terms of years.
The most important tools for paleontologists are collections of fossils and paleontological reports (with fossil plates for identification) from other locations in the region or around the world.
Micropaleontologists and palynologists work with microscopes or scanning electron microscopes (SEM).
Paleontologists frequently work in conjunction with other scientists utilizing any number of other geochronology methods.
Like fossils, the chemical and physical characteristics of rocks, minerals, and organic materials can be used for correlation.