Absolute dating carbon 14 relative dating practice
Before the advent of absolute dating methods in the twentieth century, nearly all dating was relative.The main relative dating method is stratigraphy (pronounced stra-TI-gra-fee), which is the study of layers of rocks or the objects embedded within those layers.These include the uranium-thorium method, the potassium-argon method, and the rubidium-strontium method. Thermoluminescence (pronounced ther-moeloo-mi-NES-ence) dating is very useful for determining the age of pottery.When a piece of pottery is heated in a laboratory at temperatures more than 930°F (500°C), electrons from quartz and other minerals in the pottery clay emit light.Narrow rings grow in cold or dry years, and wide rings grow in warm or wet years.The rings form a distinctive pattern, which is the same for all members in a given species and geographical area.This method is based on the assumption (which nearly always holds true) that deeper layers of rock were deposited earlier in Earth's history, and thus are older than more shallow layers.
These plants are eaten by animals who, in turn, are eaten by even larger animals.Eventually, the entire ecosystem (community of plants and animals) of the planet, including humans, is filled with a concentration of carbon-14.As long as an organism is alive, the supply of carbon-14 is replenished.With sensitive instrumentation, this range can be extended to 70,000 years.In addition to the radiocarbon dating technique, scientists have developed other dating methods based on the transformation of one element into another.
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The age of the remains of plants, animals, and other organic material can be determined by measuring the amount of carbon-14 contained in that material.