Re: Lab Ideas Wanted

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>Re. Roy's request for lab ideas

Some years ago I read an article describing the inclusion of a C/C soda can
(universal drink that shall not be named) in the top sediment of a deep sea
drilling program core. (Alas, I could not re-find the reference when I
tried again, more recently.). It sparked an idea for a first-level
Geological Time lab exercise. C/C soda cans will surely be index fossils
for the late 20th Century: they are now almost universally distributed as
trash (except in South Australia where they bring 5 cents refund; and
Oregon etc). I set about collecting C/C cans on field trips. In deserts
they remain in good condition for decades. SCUBA diving allowed retrieval
of less well preserved C/C "fossils". Some people actually collect them as
a hobby. I collected enough to assemble 3 similar sets of cans varying in
age and condition. Numbers codes were added for reference. The aim of the
exercise is to use first principles in erecting a C/C can chronology,
complete with Zones. Students are required to work in small groups, first
deciding what criteria are useful for determining the order of manufacture.
At first they use the "condition" of the can: fading of paint, rust etc.
After the first class discussion they begin to think of more reliable
criteria, that do not depend on the place where cans were found. The
opening technology, material construction, logo design, imperial vs metric
contents, local recycling regulations, special events are all effective
bits of evidence for determining a chronology. For further information
students are referred to a readings: e.g. a recent Scientific American
article on drink can technology; Hunt, C.H. 1959. "Dating of mining camps
with tin cans and bottles: GeoTimes, Vol. 3, No.8.
Like all analogous systems this one has its faults: the chronology of
fossils is not determined after collection, but in reference to
stratigraphic sequences. However, C/C soda cans are useful because of the
regional variations due to phased introduction of technology and different
laws on the use of rip-tops or can recycling. Collections can be made from
old dumps in disused settlements, and students asked to determine the
settlement time range in terms of the  C/C can Assemblage Zones.
Students like the exercise because they can bring their own knowledge and
observational skills to the problem. Real fossils are mystery objects to
students who now have very little knowledge about living organisms (since
teaching physiology went out of fashion). When asked to relate the exercise
to the fossil record, best student produce new insight every year.


                Regards,
                                Jim Gehling

J.Gehling@unisa.edu.au

Address: University of South Australia
         School of Human and Environmental Sciences
         Salisbury Campus, Smith Rd
         Salisbury East
         South Australia 5109

Phone: +61-8-3025176
Fax:   +61-8-3025082