Potassium argon dating advantages and disadvantages
This can also occur when isotopes are exposed to extreme temperatures, weathering or chemical processes.
To avoid this simple pitfall, a geologist must be sure to take mineral and rock samples from freshly broken pieces, rather than exposed or weathered surfaces.
Geologists can employ two basic methods to dating rocks and fossils.
Relative and absolute geologic dating practices have their strengths and weaknesses, which are inherent to their process.
The weakness of relative dating is inherent to its very nature.Geologists often need to know the age of material that they find.They use absolute dating methods, sometimes called numerical dating, to give rocks an actual date, or date range, in number of years.The Law of Superposition indicates that the oldest layers will be on the bottom, the youngest on the top.Likewise, the Law of Cross-Cutting Relationships holds that any igneous intrusion or physical change such as faulting, must have occurred after the deposition of the strata that it cuts through, and thus, must be older than those particular rocks.
For example, a scientists will be able to say Layer A is older than Layer B, and Layer C cuts across Layer A; therefore, Layer C must be younger than A.