Relative Dating

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Digging Up the Past:
Paleoanthropology and
Archaeology
Lecture Objectives
 Identify the importance of fossil in understanding
the behavior and anatomy of ancient hominins.
 Identify the differences between paleoanthropology
and archaeology.
 Compare the similarities and differences between
relative and chronometric dating.
 Be able to identify and describes examples of relative
and chronometric dating.
Paleoanthropology and Fossils
Paleoanthropology
 Biological anthropology focus: study of earlier
hominids, including
 1.
 2.
 3.
 4.
 Highly _____________
What do paleoanthropologists examine?
 FOSSILS
 Remember Cuvier –
he recognized that
fossils were once
living organisms
 BUT fossils were not
important in the
realm of science until
William Smith
(engineering
surveyor)
Why Fossils? What information do they hold?
 Provide direct ______________
 Study of fossil centered on two
factors

Time 

Environment 
Taphonomy & Fossilization
 Commonly bones and
teeth sources (comprise 99 %
of fossil record)
 Taphonomy
1.
 2.

Dating Methods
Dating – Why Bother?
 Placing sites and fossils into a time frame
 Dating techniques
Relative Dating 
 Chronometric Dating (numerical dating)  What is the
numerical age?
 Isotope Dating  rate at which various ___________
_____________________________________

Relative Dating
 Tells the paleoanthropology that something is older or
younger than something else
 Does provide:
 1.
 2.
 Does not provide:
 1.
 2.
Relative Dating #1: Stratigraphy
 Study of __________________________
 Variety of locations can be compared via chemical, physical and
other properties
 Law of _______________
 Lower stratum (layer) is older than a higher stratum
 Problems
 Earth distributions
 Length of time to accumulate stratum
Relative Dating #2: Biostratigraphy
 Employs the associations of fossils in strata to
determine each _________________
 Aim is ________________
 Why?

Demonstrates that a particular geological section in one location
represents the _______________ as another geological section at
some other section
Relative Dating #2: Biostratigraphy
 Index Fossils – _____________________
 Example of Irish Elk (died out: 10,600 yBP in
Europe)
Relative Dating #2: Seriation
 Typological sequences of artifacts

Assumption: ___________________

Frequency of co-occurrence of artifacts in specific
contexts

_____________________
Indicator of ____________________

Relative Dating
#2: Seriation
 Example:
Contextual
seriation
 Pottery -style rather
than function
Numerical Dating
 Dating technique that gives an estimate in actual
numbers of years

_______________________
 We will cover both isotopic and non-isotopic methods:
 Radiocarbon
 Radiopotassium
 Argon-Argon
Numerical Dating #1: Radiometric
 Carbon isotopes: Ratio of 14C to 12C is measured
 Baseline for start of clock – death of organism
 By
calculating the ratio of 14C to 12C one can determine
______________________________
 Used for material younger than 50,000 – not the
best for primate and human evolution

Archaeologists NOT __________________
Numerical Dating #2: Radiopotassium
 Non-organic material (e.g. igneous (volcanic) rock)

40K
decays slowly from its unstable form to a stable
gas, 40Ar  __________________________
 Dates material older than _________________
 Note – cannot date sedimentary rock
 First used at ____________________
Numerical Dating #3: Argon-Argon

40Ar
– 39Ar: volcanic rock is bombarded with “fast”
neutrons in a nuclear reactor
 Advantage: ______________________________
• Example: ______________________
Numerical Dating #3: Argon-Argon

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