Why is radiocarbon dating only rarely applied in geological work
Contamination can also be from old carbon sources as may occur in areas where coal beds are a part of the local bedrock stratigraphy and old coal fragments find there way into the much younger glacial lake sediment.
How radiometric dating works in general Why methods in general are inaccurate Why K-Ar dating is inaccurate The branching ratio problem How Errors Can Account for the Observed Dates Why older dates would be found lower in the geologic column especially for K-Ar dating Do different methods agree with each other on the geologic column?
A varve sequence might also have events in it of known calendar age, such as beds from flood events or volcanic ash layers that have historic records associated with them.
The more usual case is when numerical ages (estimates of true calendar ages) based on radiometric or other techniques are applied to varves.
The most reliable ages are from fossils that got their carbon directly from the atmosphere.
If you want accurate results, the bottom line is that the C ages are obtained and the bad apples reveal themselves.
The exact placement of radiocarbon samples and resulting ages relative to other varves in a varve sequence immediately eliminates one form of uncertainty.
An additional requirement for accuracy is that the fossil samples do not have a significant lag time associated with their deposition in a lake.
Bulk sediment samples and samples of aquatic plants or animals such as the carbonate shells of clams, snails, and ostracodes may yield ages that are too old because of how carbon was fixed by the organism and the potential for the incorporation of “old” carbon from a water body.Laboratory procedures may not be fully able to remove the contaminants.Perhaps the most vexing problem in some outcrop studies are pervasive tiny rootlets from modern plants.The calibration of a glacial varve record, series, or chronology is accomplished by applying numerical or calendar ages to existing varve numbers.
The true calendar age of a varve sequence can be obtained in areas where varves can be counted back from the present in modern lakes with varve deposition.Possible other sources of correlation Anomalies of radiometric dating Why a low anomaly percentage is meaningless The biostrategraphic limits issue Preponderance of K-Ar dating Excuses for anomalies Need for a double-blind test Possible changes in the decay rate Isochrons Atlantic sea floor dating Dating Meteorites Conclusion Gentry's radiohaloes in coalified wood Carbon 14 dating Tree ring chronologies Coral dating Varves Growth of coral reefs Evidence for catastrophe in the geologic column Rates of erosion Reliability of creationist sources Radiometric dating methods estimate the age of rocks using calculations based on the decay rates of radioactive elements such as uranium, strontium, and potassium.