ARCHAEOLOGY  CANADA
Chapter 6 - How Old Is It?

INFORMATION  ABOUT  ARCHAEOLOGY

Archaeologists sometimes remove recent soil layers (like sod or asphalt) with shovels or machines in order to reach the older soil layers.  But how do archaeologists know which layers are old and which are new?

There are several clues archaeologists can use:

1. Geology (the study of the Earth) teaches archaeologists that:
a) soil layers on top are usually younger than layers on the bottom;
b) certain soil types are found in certain environments only.  This helps an archaeologist know which order layers should be found in and what they should look like.

2. Inclusions - the things in the layers help the archaeologist date the layer (i.e. tell how old it is) Artifacts that are recognizable for a certain date are called diagnostic artifacts.  Sometimes ash or charcoal may be in a layer.  Geological records (of things like the dates when volcanoes erupted and created ash layers) or chemical tests can give archaeologists dates for the ash or charcoal.

For the things and artifacts in the layers, if they aren't diagnostic, archaeologists research a date for them by:
-looking up in old catalogues to find when they were made, or popular;
-doing chemical or other scientific tests on the artifacts or the things in the same layer as the artifacts;
-knowing which layer it came from - whether it is older or younger than the things above or below it.

Dating something by knowing what is older or younger than it is, is called relative dating.  Dating something by giving it a known date is called absolute dating.  Archeologists use the term Before Present  or B.P.  to give absolute dates.  Something from 150 years ago would be dated 150 B.P.
"Present" changes every fifty years, so archaeologists adjust their dates each fifty years.  This seems a lot, by over tens of thousands of years, it isn't.

QUESTIONS

1. Name three ways an archaeologist uses to date an artifact.

2. Define relative and absolute dating.

3. Why is the order of soil layers important for dating to archaeologists?

4. Discuss why archaeologists would use the term B.P. instead of B.C. or A. D. in Canada.
(note: B.C. means "Before Christ" and A.D. means "Anno Domini: or "Year of Our Lord")

GOALS

to introduce the terminology and processes used in archaeological work to date artifacts, soil layers and sites
apply the skills and knowledge from previous lessons to emphasize the interconnectedness of the different aspects of (archaeological) research.

OBJECTIVES

Knowledge
-students will list the dates for Canadian historical periods and the artifacts that are typical for them

Skills
-write descriptions of artifacts
-undertake research about the dates of artifacts
-synthesize information (place dated artifacts into correct soil layer, note appropriate tests for dating given artifacts)
 -make a time line

Attitudes
-examine the academic and public responsibilities of scientists

VOCABULARY

absolute (date)
-a numerical date, noting a specific length of time (e.g. 5 years ago)

B.P.              
-Before Present - a term used by archaeologist for writing dates (e.g. 100 B.P. is 100 years ago)

catalogue     
-(noun) a list of items and their descriptions
-(verb) the making of a list of items and their descriptions

dating          
-making tests and noting evidence to determine the age of an artifact, feature, layer, etc. in archaeological work

diagnostic artifact    
-an artifact that was so common for a specific time or group of people that it is easily recognizable and helps to note the date or people being studied

geology       
-the study of the Earth's soils, layers and minerals

relative (date)      
-a date given to something by noting that it is older or younger than something else

RESOURCES

Eatons
1901 Catalogue Toronto: reprinted 1973.

Goden, Geoffrey
Goden's Guide to European Porcelain London: Abbeville Press, 1993.

The Hudson's Bay Company Fall/Winter Catalogue 1910-1911, Toronto: reprinted 1970.

Lessard, Michel et Huguette Marquis
Encyclopédie des Antiquités du Québec Ottawa: Les Editions de L'Homme Ltée, 1971.

Sears, Roebuck and Co.
Consumers Guide Fall 1900 Chicago:  Digest Books, reprinted 1970.

Stevens, Gerald
Early Canadian Glass  Toronto:  McGraw-Hill Ryerson Limited, 1960.

Unitt, Doris and Peter
Treasury of Canadian Glass Peterborough:  Clock House, 1969.

Unitt, Doris and Peter
Unitt's Across Canada Bottle Price Guide Winnipeg:  National School Services, Ltd. 1980.


SUGGESTED  LESSONS

Junior
 Intermediate
 Extension
Students should change Continuing from the activity in the previous chapter, students will be in groups, examining the contents of garbage containers.

Provide each group with a worksheet from this book to complete.  Students will list and describe the artifacts from their garbage container.  They will conduct research and use reasoning to record the absolute and/or relative date for each artifact and list their evidence.
 Provide students (in groups or as individuals) with:
1. Photographs from this publication, of artifacts from a fictitious site;
2. information from the regional resource material about the dates of artifacts.

Using these and other resources, students will research the dates of artifacts from the site and record them and their evidence on the worksheet from this publication.		 Divide the class into groups. Provide each group with:
1. the description of tests used in archaeology to do dating;
2. one of the scenarios below:
-a campfire,
-a cabin foundation with trees growing on the interior,
-a pottery sherd (fragment)
-a fossilized bone
-an unfossilized bone

Groups decide which test is appropriate for each scenario and share their findings.

EVALUATIVE  STRATEGIES

Junior
 Intermediate
 Extension
Each group of students will construct a timeline for its garbage container, noting the place of each artifact on the line, by date.

Students could construct two timelines - one based on absolute and one based on relative dates and compare them.
 In the field notes/Site Report being kept for this unit, students should record their conclusions about:
1. the date range of artifacts for the site;
2. the median date of artifacts for the site;
3. the modal date of artifacts for the site;
4. the above for each layer on the site.		 Students should design an experiment to test the dating of an artifact.

example: Place buble gum wrappers in the sun.  Note the rate of fading of the print on the wrappers. (Compare this to the rate of fading of a buried newspaper.)

DISCUSSION

Junior
 Intermediate
 Extension
Do you have the (legal and ethical) right to look at other people's garbage?  What are the regulations for ownership and salvage at the local dump or for garbage collection?

For what date period does the right to look at garbage change? (50, 100, any year i.e. when does garbage become artifacts?) Why does time make a difference?

Students should note the presence of artifact 17 and discuss:
1. (How) Does it affect the dates given for the site?
2. Should the archaeologists have any responsibilities to the local First Nations because the artifact is present?

 Dates for sites and artifacts are often recalibrated as scientific tests are refined. Discuss:

Does the above mean that test results cannot be taken as correct and the dates for things like fossils are not facts?

Why might some people accept dating tests to locate oil and gas deposits, but not to date fossil human remains?

Should archaeologists withhold their findings at any time because they offend some people?

RESOURCES
Junior
 Intermediate
 Extension
1. worksheet to complete about dates of artifacts
2. rubric

1. artifact photographs
2. regional resource pages with artifact dates
3. worksheet to note artifact dates
4. rubric
5. tracking sheet for Site Report		 1. dating test information sheet
2. rubric
3. answer key for chapter questions

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