ANTC17H3 Lecture Notes - Thermoluminescence

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Published on 6 Jul 2012
School
UTSC
Department
Anthropology
Course
ANTC17H3
Tuff Break
H.Habilis
-
Believed to be ancestor of h.erectus, that's why it
needed to be older than h.erectus (not older)
-
Used Argon-Argon and relative dating based on pig
morphology (bio-markers)
-
Nuclear physics (radio active isotope) and mass
spectrometers - isolate beam of particular atom,
launch it down a tube, introduce a magnet at a
bend, creating a magnetic field that bends the
isotopes at different degrees and separate the
isotopes - allowing us to measure age
-
Survey Methods
South and East Africa
Plateaus rising and exposing old
stratigraphy
Found in caves through prospecting
Archaeological visibility
Nature of how these fossils are found why in
S. and E. Africa
Where found?
-
Open desert areas with low hills called kobies
Single occupation or event
Most common site
Exception: Multiple
occupations - Palimpsest
Easier to carbon date
Open site
Rock shelter (Shelter made of
rocks without tunneling); Caves
(rock shelter with tunneling)
All are palimpsests
Shelter/Cave sites
Two sites
Olduvai Gorge
-
Field survey
Go to areas that are attractive to habitation
or occupation (water, usable rocks, etc.)
Walk around and put in test pits - little holes
in the ground
How to find sites
-
Dating Methods
Stratigraphy and Cross-dating
Beautiful horizontal stratigraphy
Burrowing animals
Water table rising (typically just
grey)
Not always the case
Sehonghong
Similar industries assumed to be from
similar time periods
Cross Dating
Relative dating
-
Absolute dating methods
Limit of 40-60,000 years ago
Most efficient, inexpensive, precise for
recent past
C12 = Stable, common
C13 = Stable, less common
C14 = Unstable, extremely rare,
decaying in to nitrogen, occurs in a
ratio to C12
Three Isotopes
C14 created by action of cosmic rays in the
upper atmosphere
After death consumption of C14 stops,
decays to nitrogen
C14 half life = 5730
Important to note that there is a margin for
error (plus/minus)
Taken from BP (1950)
Different levels of Solar Flares, Ratio
fluctuates in different areas
Use Dendochronology to account for
date and calibration
Northern Hemisphere:
INTCAL09
50 year difference from
Northern Hemisphere
Southern Hemisphere: SHCAL04
Atmospheric CO2
absorbed by plants, gets
in to organisms
Cold water takes
carbon down to a
deep ocean
reservoir (old
carbon problem),
decaying, has
upwelling in west
coasts bringing
decayed carbon to
mix with new
carbon
Says organisms in
the ocean is about
405 years older
than the world
Ocean has a mixed layer
(with plants) that have
the same process of
plants on surface BUT
there is a thermo-
hayleiign
Marine (Sea Water only):
MARINE09+(Triangle)R
Terrestrial Curves
Requires Calibration Curves
Radio Carbon Dating
-
Radio-active decay of Argon
Argon works only in volcanic scenerios
Argon 30 found in a lump of cooled lava is
the product of radioactive decay of
Potassium 40 in the original lava
Has to bracket the organism in question
K40 half-life is 1.3 billion years
Using laser method it can go back to
about 10,000 years ago
Works between 100,000-2 billion years old
Potassium-Argon and Argon-Argon dating
-
Uses Quartz crystals (sand)
Imperfections in the crystal allows it to trap
electrons when burried
When optically stimulated the crystals emit
radiation
Need to know DOSE rate
Optically Stimulated Luminescence
-
Similar to OSL but based on burnt Material
Need to know DOSE rate
Thermoluminescence
-
Environment
O16 and O18 relationships over time
Hydrogen prefer to bond with O16 when it's
cold and O18 when it's warm
Introduces error because of varying
intensity of winters
Can use the data to get the idea of
temperature throughout history
Based on the assumption of constant
deposition
Glacial and interclacial periods (Cold and not
cold)
Oxygen isotopes - temperature
-
C3 plants = Trees and bushes
C4 plants = Tropical plants and grasses
C4 more recent phenomenon
Tell diet as well as environment
Tell difference between Terrestrial and
Marine protein but only if there are no
C4 plants
C3 and C4 plants
Nitrogen can tell Trophic level or where it is on
the food chain
Measured in negative because of the
choice of standard
Delta 13C = ratio of C13 to C12
Use per million (not percent)
Plants trees and bushes (C3) get values
between -33 and -21; Average of -26
C4 = -7 and -14; average of -14
Delta 13C = -26, plant is a tree or
bush
Delta13C = -12, plant is a tropical
grass
Because they don't overlap you can
figure out what kind of plant
Get values that correlate to
their diet of plants
Delta C13 = -21 = -21 3C
consumer
Delta C13 = -14 mixed diet
Delta C13 = -7 4C consumer
Measure of Delta13C of bone or
teeth
Different in different parts of body
Fractionation
How measured
While DeltaC13 decreases at 5 ppm,
Nitrogen goes up about 2 ppm
How Nitrogen is Measured
Determine diet
Using both together
Carbon and nitrogen - vegetation
-
Palynology - Vegetation
-
Faunal remains - Type of environment
-
Methods
January-25-12
1:09 PM
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Document Summary

Hydrogen prefer to bond with o16 when it"s cold and o18 when it"s warm. Introduces error because of varying intensity of winters. Can use the data to get the idea of temperature throughout history. Glacial and interclacial periods (cold and not cold) Marine protein but only if there are no. Nitrogen can tell trophic level or where it is on the food chain. Measured in negative because of the choice of standard. Delta 13c = ratio of c13 to c12. Plants trees and bushes (c3) get values between -33 and -21; average of -26. C4 = -7 and -14; average of -14. Because they don"t overlap you can figure out what kind of plant. Delta 13c = -26, plant is a tree or bush. Delta13c = -12, plant is a tropical grass. Get values that correlate to their diet of plants. Delta c13 = -21 = -21 3c consumer.

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