The statistics are interesting, but in the case of a single coin the date
becomes a problem.
 
For our Waverly Plantation study we graphed the Lincoln penny frequency
by year and superimposed that over the production figures for each year.
We found a perfect correlation, i.e., ours was a valid sample. The more
coins produced, the more we found at the site. It is what one would
expect using probability, but still was nice to see reality reflected in
an archaeological assemblage.
 
From going through several hundred bags of coins in the early 1960s, it
was common then to find plenty of 1910s and 1920s coins still in
circulation. Circulation is relative, however, as many coins are put into
piggy banks, canning jars, etc. and sit out of circulation for years.
Childhood coin collections get spent decades later.
 
Also the mints and banks release coins into circulation at later times.
One bank held a bag of 1932 Washington quarters until the mid 1960s as
investment, but a well-meaning teller needed quarters, so $250,000 became
$400 instantly, at least for the bank. In another instance, the 1903 O
silver dollar (as I recall), only six were known and they fetched some
$40,000 each. People assumed the rest were melted down for silver by the
mint. But a few days after the last one was auctioned, the mint announced
that they had found thousands of bags, a million coins or more, and these
were released to the public in the 1960s. Made me happy to get a few, but
pitty the poor bloke who had just shelled out the $40,000. :)
 
The moral to the story, for historical archaeologists, is that one can
learn the MANUFACTURE date, but not how long an individual artifact
gathered dust before it was sold, how long it was used, and how long it
sat around before it was discarded.
 
My own research indicates that any site dated using ceramic manufacturing
dates ends up being attributed in the literature some 20-30 years earlier
than it actually was occupied.
 
 
 
 
William Hampton Adams,
  Director of Studies
Department of Archaeology
Flinders University
GPO Box 2100
Adelaide 5001, S.Australia
 
Phone: + 61 8 8 201 5257
Fax:   + 61 8 8 201 3845
 
See Archaeology at Flinders on our website at
http://cmetwww.cc.flinders.edu.au/Archaeology/Home_Page.html
 
See an entire site report on the excavations in Fairbanks, Alaska at:
http://cmetwww.cc.flinders.edu.au/Archaeology/Heritage/Barnette/Start