2. Review – Relative Dating
• Typology
– computer typology
• Stratigraphy
– Try the following examples
3.
4. Calendars
• Count years
• Many different calendars in the world
• We use Gregorian calendar
• In the European cultures, the year count
based on birth of Christ
5. Calculating Today’s Date
Gregorian Julian Islamic Hebrew
16 February 2015
AD
3 February 2015
AD
26 Rabi’ath-Thani
Shawwal 1436 AH
(anno hegirae ‘in the
year of the Hijra’
27 Shevat 5775 AM
(anno mundi ‘in the
year of the world’)
9. Birth of Jesus
• AD stands for Anno Domini ‘in the year of our
Lord’
• According to Dionysius Exiguus, Jesus was
born in AD 1 but most scholars now think it
was in fact 6 BC
• The year before Jesus’ birth is 1 BC
• System is NOT a mathematical number line
• There is no year 0
10. BCE/CE Dating System
• BCE means Before the Common Era
• CE means the Common Era
• Numeric date the same as BC/AD system
– Examples
220 BC = 220B CE
AD 499 = 499 CE
• Question: Why have a new system?
11. BP Before Present System
• You may also see, especially in scientific
contexts the BP dating system
• This is often used for very big periods of time
• To calculate the BCE/BC date take the BP date
and minus this year (or the year of
publication)
– Example: 40 000 BP = 40 000 – 2015 = 37 987 BCE
12. Bigger Units of Time
• What is a millennium?
• What is a decade?
• What is a century?
• How are centuries named?
• Activity
13.
14. How do we date artefacts?
• Relative dating
– Examples
– Only gives sequence in relation to other objects
from the site
• Absolute dating
– Gives a date for an object (within a probable
range)
15. Absolute Dating Methods
• Scientific ways to arrive at precise dates
include:
– Radio-carbon dating
– Dendrochronology
– Potassium-Argon dating
– Thermoluminescence dating
– Amino-acid dating
17. Dendrochronology
• Traditional method for establishing absolute
date
• Also called Tree Ring Dating
• Based on principle that growth rings in some
species of tree reflect seasonal and annual
rainfall
– Good rainfall = large growth ring
– Low rainfall = small growth ring
– Also uses fire scars
18.
19. Growth Ring Data Base
• Growth ring data collected from many trees in a
specific area
• Data base of growth rings built up
• Growth rings sequences matched to data base
– Trees from the same species, growing in
the same area or environment will be exposed to
the same conditions, and hence their growth rings
will match at the point where their lifecycles
overlap.
• Absolute date determined
20. Weaknesses of Dendochronology
• Some species do not have distinctive growth
rings (especially in tropical areas)
• Wood must be well preserved
• There must be an existing master strip in the
data base to match up with the wood
21. Activities
• Complete the dendrochronology activity
• Complete the dating systems activity
• Go onto CGS Connect and look at the Prep for
this week
