archaeology midterm2 lecture2
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- The use of annual growth rings in trees to assign calendar ages to ancient wood samples
- Tree-ring dating (dendochronology)
- Tree-ring dating (dendochronology) developed by
- Douglass
- Douglass worked in...
- SW/Arizona
- trees are ____ in winter and ____ in spring
- dormant, active
- Dendochronology helped to date ____
- Betatakin
- ____ collected more samples in Betatakin from building materials in various rooms
- Dean
- Age of the final ring
- cutting date
- Tree-ring width is a function of ______and _____
- precipitation, temperature
- Radiocarbon dating discovered by...
- ...Libby
- What carbon isotope is used in radiocarbon dating?
- 14
- What do you measure in radiocarbon dating?
- Beta emissions
- The time required for half of the carbon-14 available in an organic sample to decay
- libby half-life
- what is the standard libby half-life
- 5568
- When is the present?
- AD 1950
- what 2 things are hard to date?
- bones, plants
- The specific chemical process through which plants metabolize carbon; the three major pathways discriminate against carbon-13 in different ways, therefore similarly aged plants that use different pathways can produce different radiocarbon ages
- photosynthetic pathways
- When organisms take in carbon from a source that is depleted of or enriched in carbon-14 relative to the atmosphere; such samples may return ages that are considerably older or younger than they actually are
- reservoir effect
- ____ was first to find fault in atmospheric assumption
- De Vries
- - Fluctuations in the calibration curve produced by variations in the atmosphere’s carbon-14 content; these can cause radiocarbon dates to calibrate more than one calendar age
- De Vries effects
- why is only the part of the site needed to answer the research question excavated?
- digging destroys data that we don’t know yet to collect
- A method of radiocarbon dating that counts the proportion of carbon isotopes directly (rather than using the indirect Geiger counter method), thereby dramatically reducing the quantity of datable material required
- Accelerator mass spectrometry (AMS)
- ____ found four grains of domesticated barley and one grain of wheat in southern Egypt
- Wendorf
- Forms of dating that rely upon the fact that electrons become trapped in minerals’ crystal lattices as a function of background radiation; the age of the specimen is the total radiation received divided by the annual dose of radiation.
- trapped charge dating
- trapped charge dating identifies...
- ... the last time a specimen had its electron traps emptied
- A trapped charge dating technique used on ceramics and burnt stone artifacts- anything mineral that has been heated to more than 500 degrees C.
- thermoluminescence
- thermoluminescence doesn't work if...
- ...artifact was accidentally burned years after manufacture
- An early form of humans who lived in Europe and the Near East about 300,000 to 30,000 years ago
- Neanderthals
- 3 ways to determing total radiation dose
- thermoluminescence, optically stimulated luminescence, electron spin resonance
- A trapped charge dating technique used to date sediments (dirt); the age is the time elapsed between the last time a few moments exposure to sunlight reset the clock to zero and the present.
- optically stimulated luminescence
- optically stimulated luminescence works best with...
- ...eolian sands
- A trapped charge technique used to date tooth enamel and buried stone tools; it can date teeth that are beyond the range of radiocarbon dating.
- electron spin resonance
- ___ changed understanding of human evolution
- electron spin resonance
- A device to measure the amount of gamma radiation emitted by sediments (annual dose). It is normally buried in a stratum for a year to record the annual dose of radiation
- dosimeter
- what 2 methods are used to date the age of formation of a particular layer of rock?
- potassium-argon and argon-argon
- An absolute dating technique that monitors the decay of potassium into argon gas
- potassium-argon dating
- ____ was used to estimate age of homo erectus
- potassium-argon dating
- 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
- homo erectus
- for potassium-argon dating to work,
- there must have been no argon trapped at the time of formation
- A high-precision method for estimating the relative quantities of argon-39 to argo-40 gas; used to date volcanic ashes that are between 500,000 and several million years old
- argon-argon dating
- A potential problem with radiocarbon (or tree-ring) dating in which old wood has been scavenged and reused in a later archaeological site; the resulting date is not a true age of the associated human activity.
- old wood problem
- ____ and ____ dated the pyramids through radiocarbon dating on the mortar
- Nakhla, Hawass
- Nakhla and Hawass dated the pyramids through _____ on the mortar
- radiocarbon dating
- 2 ways to date material remains
- direct, indirect
- Analysis of the artifact, ecofact, or feature itself to arrive at a chronological evaluation
- direct dating
- Analysis of material associated with the data under study to derive a chronological evaluation
- indirect dating
- Determining age or chronological sequence without reference to a fixed time scale
- relative dating
- Relies on comparisons with other forms of data to determine “older than†or “younger thanâ€Â
- relative dating
- Determination of age on a specific time scale, as in years before present, or according to a fixed calendrical system
- absolute dating
- Example: A series of artifacts found in an excavation that stylistically represent different time periods (dates unspecified) are dated relative to one another
- Direct Relative Dating
- Example: An artifact is dated using a method like radiocarbon dating to specific year, or spread of years
- Direct Absolute Dating
- Example: A series of artifacts are extracted from different strata/levels (dates unspecified) of an excavation and are dated relative to one another
- Indirect Relative Dating
- Example: A series of artifacts are extracted from a strata/level/feature in an excavation that has been dated to a specific time period
- Indirect Absolute dating
- The date after which an artifact or feature must have been deposited
- Terminus post quem
- The date before which an artifact or feature must have been deposited
- Terminus ante quem
- Based on physical comparisons such as stratigraphic placement in relation to other remains
- relative dating
- Able to date individual items with or without comparisons to other remains
- absolute dating
- Useful in clearing up questions of duration of time periods in a chronology
- absolute dating
- Able to place archaeological sites in chronological context if they lack diagnostic information
- absolute dating
- 5 relative dating methods
- stratigraphic analysis/geochronology, biostratigraphy, temporal types, seriation, FUN dating
- Stratigraphic analysis/geochronology governed by...
- ...law of superposition
- How to date materials found within soil or bedrock layers when they can be dated relative to materials in others
- stratigraphic analysis/geochronology
- Under what condition can geochronology be absolute?
- if the layer of bedrock containing remains has been dated
- Why is geochronology considered relative?
- the range of dates can be extremely large
- Archaeological association of cultural material with extinct animal or plant species
- Index fossils (biostratigraphy)
- What is comparable to geochronology for obtaining date ranges?
- biostratigraphy
- What is a problem with biostratigraphy?
- Exact date ranges may not be known for the species
- The association of particular remains with remains of a known type
- Temporal typing
- Techniques used to order materials in a sequence, in such a way that adjacent items in the series are more similar to each other than to items further apart in the series
- seriation
- how is seriation done most often?
- by an examination of stylistic attributes
- what are the three things that can be looked at for seriation?
- stylistic, form, technological
- what is seriation usually done in combination with? (2 things)
- stratigraphic and frequency analysis
- A relative measure that examines the ratio of nitrogen to fluorine and uranium in bone
- Flouride/Uranium/Nitrogen (FUN) dating
- WHat means a younger date in FUN dating?
- More nitrogen
- What is FUN dating affected by?
- climate
- The study of tree ring patterns among trees both living and dead and linking them to develop a continuous chronology
- dendochronology
- The iron particles in certain materials that are heated to 700 degrees Celsius will reorient to the position of MNP at that time
- archaeomagnitism
- Requires that materials have been left in place since heating
- archaeomagnitism
- Measures the amount and rate of the absorption of water on the surface of a piece of obsidian
- obsidian hydration
- 2 factors affecting absorption rate in obsidian hydration
- source of obsidian, environmental conditions