was one of the questions Eli and the bunnies wrestled with as a possible stumper on our comprehensive exams. AGU has another: Define the Anthropocene
But it has to be done in terms of what the cyanobacteria, or whatever succeeds humans, will be able to spot in 100K years or more. Paul Crutzen introduced the term to describe an epoch in which humans dominate changes to the Earth, but for the geologists (and they have the last word in naming epochs) it has to be done in terms of traces in the solid Earth at the stratigraphic level.
There is a working group and there was a symposium on this issue at the 2012 AGU and an article in EOS Jan 22. Anthony Barnosky from UC Berkeley pointed to
some applicable biostratigraphic evidence for the placement of the Anthropocene boundary could include biostratographic zones for taxa lineage, assemblage, and abundance. He also noted that the road system could be a useful boundary layer. Barnosky said that roads, which often include several layers of geologically resistant human-derived strata, “are probably going to be a more significant boundary layer in the long run than the K-T boundary clay.” Defining the Anthropocene as a formal epoch “clearly is already supportable by paleontological principles you would apply for other epochs,” and biostratigraphy argues for a Holocene-IEHO, some of the folks are too hung up on assigning an exact date. You can't do that for other Epochs.
Anthropocene boundary near 1950, he noted.
What say thee. The Subcommission of Quaternary Stratigraphy is interested in hearing.