An introduction to dating systems for early high school and middle school.

2. BIGGER UNITS OFTIME
• What is a millennium?
• What is decade?
• What is a century?
• How are centuries named?

4. ACTIVITY
• Complete the Dating Systems activity in your workbook
(PDF on the class page)

5. RELATIVE DATING
Source: http://www.crowcanyon.org/index.php/stratigraphicdating
• Only gives a sequence in relation to other
objects
• Is more useful when you know more about
surrounding layers and materials

6. ABSOLUTE DATING
• Gives a definite date range for an object
• It is the most precise method
• It is not reliable on all objects
• Objects can be made from materials from earlier time periods (e.g. wood
and stone)

7. ABSOLUTE DATING METHODS
• Radio-carbon dating
• Dendrochonology
• Potassium-Argon dating
• Thermoluminescence dating
• Amino-acid dating

8. RADIO-CARBON C-14 DATING
Video: ScientificAmerican Instant Egghead number 28

9. DENDROCHRONOLOGY
• Traditional method for establishing absolute date
• Also calledTree 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

11. 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

12. WEAKNESSESOF
DENDROCHRONOLOGY
• 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

13. ACTIVITY
• Complete activities 2 and 3 on the CGS connect page