Radiocarbon dating involves determining the age of artifacts by

The layers of sedimentary rock, or strata, can be seen as horizontal bands of differently colored or differently structured materials exposed in this cliff.The deeper layers are older than the layers found at the top, which aids in determining the relative age of fossils found within the strata. Such index fossils must be distinctive, globally distributed, and occupy a short time range to be useful.SAN FRANCISCO, March 23, 2010 — Scientists today described development of a new method to determine the age of ancient mummies, old artwork, and other relics without causing damage to these treasures of global cultural heritage.

If a fossil is found between two layers of rock whose ages are known, the fossil's age is thought to be between those two known ages.

Because rock sequences are not continuous, but may be broken up by faults or periods of erosion, it is difficult to match up rock beds that are not directly adjacent.

The radiocarbon dating method is based on the fact that radiocarbon is constantly being created in the atmosphere by the interaction of cosmic rays with atmospheric nitrogen.

The resulting radiocarbon combines with atmospheric oxygen to form radioactive carbon dioxide, which is incorporated into plants by photosynthesis; animals then acquire in a sample from a dead plant or animal such as a piece of wood or a fragment of bone provides information that can be used to calculate when the animal or plant died.

Paleontology seeks to map out how life evolved across geologic time.

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