Chapter 6 Terminology Flashcards
Absolute date
A date expressed as a specific unit of scientific measurement, such as days, years, centuries, or millennia; an absolute determination attempting to pinpoint a discrete, known interval at time.
Accelerator mass spectrometry (AMS)
A method of radiocarbon dating that counts the proportion of carbon isotopes directly (rather than using Geiger counter method), thereby dramatically reducing the quality of datable material required.
Argon-argon dating
A high-precision for estimating the relative quantities of argon-39 to argon-40 gas; used to date volcanic ashes that are between 500,000 and several million years old.
de Vries effects
Fluctuations (διακυμάνσεις) in the calibration curve produced by variations in the atmosphere’s carbon - 14 content; these cause radiocarbon dates to calibrate to more than one calendar age.
Dosimeter
A device to measure the amount of gamma radiation emitted by sediments. Often a short length of pure copper tubing (χάλκινους σωλήνες) filled with calcium sulfate (θειικό άλας), it is normally buried in a stratum for a year to record the annual dose of radiation.
Electron spin resonance
A trapped charge technique used to date tooth enamel and burned stone tools; it can date teen that are beyond the range of radiocarbon dating.
Half-life
The time required for half of the carbon-14 available in an organic sample to decay; the standard is 5568 years,although it is known that the half-life is closer to 5730 years.
Homo erectus
A hominid who lived in Africa, Asia, and Europe between 2 million and 500,000 years ago. These hominids walked upright, made simple stone tools, and may have used fire.
Index fossil concept
The idea that strata containing similar fossil assemblages are of similar age. This concept enables archaeologists to characterize and date strata within sites using distinctive artifact forms that research shows to be diagnostic of a particular period of time.
Mean ceramic date
A statistical technique for combining the median age of manufacture for temporally significant pottery types to estimate the average age of a feature or site.
Neanderthals
A hominin who lived in Europe and the Near East about 300,000 to 30,000 years ago; biological anthropologists debate whether Neanderthals were in the direct evolutionary line leading to the Homo Sapiens.
Old wood problem
A potential problem with radiocarbon (or tree-ring) dating in which old wood has been scavenged and re-used in a later archaeological site; the resulting date is not a true age of the associated human activity.
Optically stimulated luminescence
A trapped charge dating technique used to date sediments; the age is the time elapsed between the last time a few moments exposure to sunlight reset the clock to zero and the present.
Photosynthetic pathways
The specific chemical process through which plants metabolize carbon. The three major pathways discriminate agains carbon -13 in different ways, therefore similarly aged plants that use different pathways can produce different radiocarbon ages.
Relative date
Dates expressed relative organisms that took in carbon from source that was depleted of or enriched in 14C relative to the atmosphere may return ages that are considerably older or younger than they actually are.
