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3Radioisotopic Methods for Dating Rocks FACTORS AFFECTING ISOTOPIC DATINGAccuracy of isotope dating also depends on the condition of the material dated Fractured or weathered rock is not a good candidate.

Age of the rocks being considered also presents some problems.

15Radioisotopic Methods for Dating Rocks TYPES OF ISOTOPIC DATING TECHNIQUESPotassium (K) - Argon (Ar) Dating Problem with K-Ar dating is that the Argon produced is a gas and with fracturing, weathering, or metamorphism, the gas can be lost, resetting the clock.

Used to date carbon-based remains like bones, plant remains (wood, pollen, seeds), shells, cloth, paper and charcoal.

Daughter isotopes are generally lost in the process.

Dating metamorphic rocks provides the age of the metamorphic event rather than the age of the rocks themselves.

Title: FACTORS AFFECTING ISOTOPIC DATING 1Radioisotopic Methods for Dating Rocks FACTORS AFFECTING ISOTOPIC DATINGWorks best when a rock or mineral represents a closed system.

Because all three occur together, it allows a method to cross-check the dates.

11Radioisotopic Methods for Dating Rocks TYPES OF ISOTOPIC DATING TECHNIQUESUranium (U) - Thorium (Th) - Lead (Pb) Dating235U decays to 207Pb Half-life (t1/2) is 713 million years.