This thing in Snopes today got me thinking, at what point would an archaeologist consider it worthwhile to go digging in a local landfill? I’m pretty sure that Jamestown’s garbage dump might yield some interesting artifacts, but anything from the 70s onward probably would not. Is there an agreed-upon point somewhere in the middle of that timeline? Examples?
that national geographic special on garbology. the answer to your question is anywhere from a few years to several thousand years.
new york sanitarity fills were studied in the 80s. a half-eaten steak in 1978 was still intact. they dated the items using the newspapers buried along with the other goodies. they noted a rise in condom use during the herpes and then the dawning of the aids era.
after maybe a few hundred years, organic material would rot and carbonize and all you will have are the metals, glass and ceramics.
In the 80s, my old Archaeology Prof, Professor Honerkamp, did a did in a 19th Century steel foundry, Civil War Era.
Before anyone asks, the relevant SF story about landfill archaeology is “Detritus Affected” by David Brin.