Chapter 4 Flashcards
the Thera Eruption
The eruption buried the prehistoric settlement of Akrotiri
why was the Thera Eruption the prehistoric Pompeii
b. It had well-preserved streets and houses
c. Wall paintings
All buried under meters of volcanic ash
What was problematic about the date of the Thera Eruption
most recent pottery style relevant to the Minoan palaces was absolutely dated around 1450 BCE but the Akrotiri had no such pottery style
Conclusions that were drawn from the Thera eruption
Some were drawn that the Thera eruption had nothing to do with the destruction of Minoan palaces
- Others believed the eruption would have been widely felt
Why could the Thera Eruption have been widely felt
Ash samples from the Thera eruption were identified in samples from the Minoan Crete sites
what did tree rings show about the Thera Eruption
Was not able to convincingly associate the date from the tree rings (1628-1626 BCE) to the Thera eruption
what was studied by the tree rings at the Thera Eruption
Tree-ring would have narrow rings from the reduced solar radiation reaching the earth caused by the dust
what did ice cores show about the Thera Eruption
Revealed a short peak of high acidity for major eruptions on a scale for global effects
what did radiocarbon dating show about the Thera Eruption
- Concluded the eruption was between 1663 and 1599 BCE until an olive tree placed the eruption between 1627 and 1600 BCE
what is the problem with the Dating of the Thera Eruption?
The radiocarbon dating dates go against the date set by cross-referencing with Egyptian historical chronology (1520 BCE)
Most obvious ways of measuring time:
- Alternating light and dark of night and day
Annual cycle of the seasons
The main source of error in dating methods
Archaeologist
To date something in a meaningful way
The timescale has to relate to a fixed point in time
BCE
Before Common Era
CE
In the Common Era
In Paleolithic uses the terms “BP” and “years ago”
interchangeably
Relative dating
First (maybe most important) step archaeological research for ordering things
Relative dating include
Stratigraphy
Topology
seriation
Linguistic Dating
Changes in earth’s climate
Stratigraphy
Laying down or depositing of strata or layers (deposits) one above the other
principle of superposition
a. Provides a relative chronological sequence
b. Oldest and earliest layer is at the bottom
c. Newest and latest layer is at the top
why is association important in stratigraphy
When artifacts were found in association, they were buried at the same time
The most reliable dating of archaeological sites
The combination of the stratigraphic sequences and absolute dating
Sometimes the deposit itself is important because
it also shows human behavior
Typology
One can make a chronological order of artifacts sometimes by looking at them
non-archaeologist way of using typology
a. One artifact looks older than another
b. One artifact’s clothing looks more “old-fashioned”
Archaeologists define the form of an artifact as an attribute of
a. Material
b. Shape
Decoration
how does typology group things together
into types
Two ideas underlying the notion of typology in dating
Products of a given period and place have a recognizable style
Changes in style (shape and decoration) of artifacts is often gradual or evolutionary
how can artifacts often be identified
by their style and place in the correct typological sequence
Particular artifacts produced at about the same time
are often alike
the backbone of the chronological system
pottery typologies
why is pottery the best chronological system
a. Every area usually has its own well-established ceramic sequence
b. Pottery surface decorations change rapidly
what is not useful for typological sequences
stone tools are very slow to change
Seriation
The idea of “like goes with like”
what does seriation allow
a. Assemblages of artifacts to be arranged in a serial order
b. Used to indicate their ordering in time or relative chronology
who was the first to develop a technique for arranging graves in a cemetery in relative order
William Flinders Petrie
Battleship curve
a. The idea that an artifact (ex. Ceramic style) will usually start small
b. Rises to a peak as the style gains popularity
c. Declines again after
Linguistic Dating
study of languages
The basic principle of linguistic dating
If two groups of the same speaking language are separated with no contact, they will continue speaking the same tongue
YET
In each population, with the passage of time, there will be changes.
AS A RESULT
After a few centuries, the groups will no longer be speaking the same language until the languages will be unintelligible to the other
Lexicostatistics
study changes of vocabulary
Glottochronology
uses a formula to pronounce how many years ago the languages diverged
Phylogenetic analysis
the development of tree diagrams from the vocabulary data then systematically comparing unknown dates with points of divergence between languages.
Climate and Chronology techniques
- ice cores
- deep-sea cores
- pollen dating
Deep-sea cores
Most coherent record of climatic changes on a world-wide scale
what do deep-sea cores have
organisms known as FORMANINIFERA
what do the organisms know as FORMANINIFERA show in deep-sea cores
A good indicator of the sea temp when the organisms were alive in the variations of the chemical structure of these shells
Cold episodes in the deep-sea cores
glacial periods of ice advance
Warm episodes in deep-sea cores
interglacial periods of ice retreat
ice cores
Annual deposits are represented through the layers of compacted ice
what is the max ice cores can date
the last 2000 to 3000 years
why do ice cores have a limit to how far back they can date
Earlier time periods are at greater depths
stratification is no longer visible
ice cores is a useful tool for the discovery of
preserved volcanic eruption evidence
Pollen dating (palynology)
Studying pollen samples from a site, it can often be fitted into a broader pollen-zone sequence and assigned a relative date
why is pollen used for dating
Pollen is almost indestructible and survives for many thousand years in all kinds of conditions
what is important to note about pollen zones
not uniform across large areas
what cannot be used for early periods of dating, such as the interglacial period
radiocarbon dating
3 most important and commonly used absolute dating methods
- Calendars and historical chronologies
- Tree-ring dating
- Radiocarbon dating
To date population events
- Genetic dating is used
During the Paleolithic period
Uranium-series dating and potassium-argon dating are used
Dating almost entirely relies on
connections with chronologies and calendars that people in ancient times established
Three points to remember when working with early historical chronologies
a. List of rulers or kings needs to be complete
b. The list shows the number of years in each reign but it still has to be linked with our calendar
c. Artifacts, features or structures to be dated at a site have to be related to the historical chronology
Maya Calendar
the most elaborate calendar
what is unique about the Mayan calendar
Does not depend on a record of dynasties and rulers like Europe and the Near East
what must be understood to understand the Mayan calendar
a. Necessary to comprehend the Maya numerical system
b. Recognize the various glyphs or signs by the various days
c. Follow how the calendar itself was constructed
the Calendar Round in Mayan is
for most everyday purposes
the Long Count in Mayan is
used for historical dates
according to the Mayan calendar, when was the present world going to end
December 23, 2012
Terminus post quem
Date after which
Terminus post quem means what about the artifact
Means the deposit can be no earlier than the date of the artifact but it can be later than that date
Terminus ante quem
Dater before which
Terminus ante quem means what for artifacts
The artifact that is buried cannot be more recent than the artifact
rivals radiocarbon as the main method of dating the last few thousand years
Dendrochronology
Basics of the method (tree-ring dating)
- The yearly rings of growth can be seen in the cross-section of the trunk
- Rings are not uniform in thickness
- A diagram of these rings is developed regarding the thickness of successive rings in a tree
- Growth can be matched between successively older timbers for the chronology of the area
- Sequences of living trees matched to old timber produces a long, continuous sequence from the present day
Rings become narrower with
increasing age of the tree
The amount of tree growth each year is affected
by climate fluctuations
Varves
The melting ice sheets each year when the temp rises leads to the formation of annual deposits of sediments in lake beds
Radioactive Clocks
Based on the widespread and regular feature of radioactive decay
Principle of radioactive decay
Carbon has three isotopes with C14 being unstable with its eight neutrons in the nucleus and not the normal six
what is the rate of radioactive decay
a constant rate independent of all enviromental conditions
Half-life
The time is taken for the atoms of the radioactive isotope to decay
After one half-life there will be
half of the atoms left
Radiocarbon’s half life is
5,730 years
Radiocarbon dating helped
the first time to establish a chronology of world cultures
Calibration
comparing radiocarbon dates to known dates
what was the problem with Libby’s assumption of radiocarbon dating
14C was assumed to be constant in the atmosphere, but it is in fact varying depending on changes in the earth’s magnetic field and the sun
Accelerator mass spectrometry (AMS)
· Requires smaller samples and controls the amount of C14 directly
C-14 contamination
organic material can be contaminated by touch
Geiger counters were an older way of radiocarbon dating that
had errors by counting daiation
what does it mean that in about 50 000 years and all the C-14 will have vanished
can only sample up to 50 000 years because anything after this means there is no meaningful amount left
C-14 dating can only be done
on things that are alive because c-14 is only ingested by living things
what happens when an organism dies
the C-14 starts to decay
how do archaeologists do radiocarbon dating
count the C-14 that’s left in the sample
Potassium-Argon dating dates from
5 mya to 100 000 years ago
what is the standard deviation of potassium-argon dating
30 000 years
potassium-argon dating focuses on
potassium 40 and how it decays slowly but consitently
Potassium-argon dating is used to date
lava and any lava remains
Uranium series dating is used to date
remains with calcium carbonate and teeth
Uranium series dating dates from
500 000 to 50 000 ya
what dating method is used for cave paintings
uranium-series dating
uranium series dating is done through the dating of
radioactive decay of isotopes of uranium
fission track dating dates from
usually over 300 000 years ago
fission track dating is used to date
minerals and natural glasses that have small amounts of uranium
how does fission track dating work
- find the tracks left in the mineral or glass
- the tracks are left by decay process
- counting the fission tracks tells how old it is
thermoluminescence dating dates from
500 000 ya to 50 ya (or the present)
thermoluminescence dating is used to date
minerals within pottery
how does thermoluminescence dating work
- minerals in pottery store energy by trapping electrons
- when the pottery is fired, it releases that energy
over time, in TL dating the energy in pottery
will build back up again
what is TL dating specifically looking for
the date the pottery was fired
what is significant about 500 000 ya in TL dating
its the max amount of energy the pottery can have
obsidian hydration is used to date
obsidian objects
obsidian hydration dates
1 mya to present
how does obsidian hydration work
- when fractured, obsidian absorbs water
- forms a measurable hydration layer
what is important to note in obsidian hydration
the absorption is not uniform so it needs to be calibrated
what do TL and obsidian hydration dating have in common
counting what has built up again in the artifacts
Archaeomagnetic dating dates up to
2000 ya
what is archaeomagnetic dating used for
dating clay
how does archaeomagnetic dating work
- clay is heated and it records the direction, intensity of earth’s magnetic field
- compare known earth magnetic history with the clay’s history
Egyptian calendars
- solar
- lunar
- religious
- civic
- regnal
what is confusing about the regnal calendar in Egypt
with a calendar year based on king’s reign, kings don’t always rule for a full year so we can’t count how many reigns of king
Julian reforms
turns the 10 lunar month calendar into 12 months
Gregorian reforms
adds a leap year to the calendar
ante meridiem
AM - before middle of day
post meridiem
PM - after middle of day
what is a fundamental linguistic rule
Words are suddenly flipped and have the opposite meaning
two types of seriation
Contextual
Frequency
Contextual seriation
You are looking and dating a bunch of things by showing how types of things are related to similar things of that same period
with contextual seriation, what can be proved
the object could be dated to a couple different periods, while a series could only be dated to ONE period
what is a flaw in contextual seriation
can’t tell what is older without contextual evidence
Frequency seriation
Something is introduced and gains in popularity and reaches its peak
Then it declines in popularity and becomes less and less popular
frequency battleship curves are based on
percentage
____ change over time and ______ changes much more quickly than _____ changes
styles and fashion and technology
dating bone deposits
measures nitrogen, fluorine and uranium content of bones
what are bone deposits used to figure out
whether or not bones found together date to the same time
index fossils
Early ways to date artifacts, fossils that appear over again in the same layers would appear again and again in the same order.
index fossils are used to
identify or date the rock or rock later in which it is found
Optical dating
Uses data minerals that have been exposed to light rather than hea
how does optical dating work
- Start point = some trapped energy that will be released by exposure to sunlight
- As the minerals are buried = accumulate electrons again from the radiation in the soil
Electron Spin Resonance (ESR) dating
- Used for material that decomposes when heated
what is ESR most successful with
tooth enamel
Useful for cross-checking other dating methods
Electron Spin Resonance (ESR) dating
Genetic Dating
Estimate timespans for human generations that can make inferences about calendar years
Global events
Building a relationship between sequences based on the occurrence of the same significance even with widespread geographical repercussions
Tephra
volcanic ash
Tephrochronology
Distinguish unequivocally in the tephra resulting from different volcanic eruptions present in terrestrial deposits or deep-sea core
