A type of dating: deciding whether one event predates or postdates another event
Relative dating
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A type of dating: assigning a numerical age to an event
Absolute dating
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Name 4 cosmogenic isotopes
14C, 10Be, 26Al, 36Cl
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The time taken for half the atoms of a radioactive sample to decay
Half-life
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What is the half-life of 14C?
5,730 years
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The process by which an unstable atomic nucleus loses energy by radiation and transform into stable isotopes, e.g. 14C -> 14N
Radioactive decay
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The exponential rate at which radioactive decay occurs as displayed on a graph
Decay curve
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The number of protons and neutrons in the nucleus of a carbon atom
Mass number
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14C forms in the upper atmosphere when 14N is bombarded by...
Cosmic rays
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A method of measurement: the counting of beta particle emissions over a standard length of time
Conventional method
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A method of measurement: an accelerated mass spectrometer is used to count the number of 14C atoms present, instead relying on emission of their daughter products. Can process smaller samples, e.g. insect remains, individual seeds, etc.
AMS method
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Rate of 14C production in the atmosphere is constant. 14C uptake by organisms is in equilibrium with their environment. No new 14C enter an organism after death, so the concentration is entirely a function of time since death. No "old" carbon is recycled
Problems of radiocarbon dating: assumptions
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Who won the Nobel prize for developing this technique in the 1940s?
Willard Libby
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Calculates an age in years for geologic materials by measuring the presence of a short-life radioactive element, e.g. 14C. A type of this dating method is radiocarbon (14C) dating.
Radiometric dating
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This technique allows the construction of year-by-year annual chronologies which can be temporally fixed (linked to the present day) or floating, e.g. dendrochronology
Incremental dating
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Other cards in this set
Card 2
Front
A type of dating: assigning a numerical age to an event
Back
Absolute dating
Card 3
Front
Name 4 cosmogenic isotopes
Back
Card 4
Front
The time taken for half the atoms of a radioactive sample to decay
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