Download Relative and Chronometric Dating

Archaeological
Dating
Methods
archaeological
dating methods
1. relative dating
(aka “older/younger” dating)
2. chronometric dating
(aka “absolute” dating)
Relative and Chronometric Dating
Understanding Humans,
10th
Ed., p. 189.
REMEMBER: relative
methods
tell you whether something is
older / younger / the same age
Understanding Humans, 10th Ed., p. 188.
methods
REMEMBER: chronometric
methods
yield a date
often scaled in calendar years
+/- a number of years (there is a
margin of error in every technique)
Understanding Humans, 10th Ed., p. 188.
Stratigraphy
the sequence of geological
strata, or layers, formed by
materials deposited by water
or wind
-Law of association
-Law of superposition
Otero, S. (2004) Social and Behavioural Science
Lecture Notes (2014). El Camino College, Torrance,
California
Main gorge at Olduvai. Note geological beds.
Understanding Humans, 10th Ed., p. 197.
Note how stratigraphy
is used to date stone
tools
Bed I
Olduvai Gorge, Kenya.
Hoebel, Anthropology: The Study of Man and Archaeology, 4th Ed., p. 153.
archaeological
dating methods
1. relative dating
2. chronometric dating
(aka “absolute” dating)
provides estimates in
actual numbers of years
(sometimes +/-)
Relative and Chronometric Dating
Understanding Humans, 10th Ed., p. 189.
chronometric dating
(aka “absolute” dating)
determining the actual age of
geological deposits (and the
fossils in them) by examining the
chemical composition of rock
fragments and organic remains
containing radioactive substances
such as uranium 238, and C 14,
which decays at a known rate. It
is a destructive method.
Direct determination of
age determined through
laboratory analysis
Here are three examples you need to know:
C14 dating of organic samples
Dendrochronology (tree ring
patterns)
Molecular clocks (slight genetic
markers that change at a known
rate)
Relative and Chronometric Dating
Understanding Humans, 10th Ed., p. 189.
Technician in a radiocarbon dating laboratory.
Understanding Humans, 10th Ed., p. 194.
Radiocarbon dating:
Don’t stress out; I
will NEVER ask you
to explain how it
works
• Method was developed in the
1940’s by Willard Libby and a
team of scientists at the
University of Chicago.
Very powerful in dating artifacts
•and
geological events up to
about 50,000 years ago.
So, if relative dating
techniques do not give you
a specific age and
chronometric dates give
you a date range, how do
archaeologists choose which
dating technique to use?