In reply to Dale Floyd, there does seem to me to be a major difference here:
If I pass myself off as an historian, professional or otherwise, all I am
likely to damage in the process is my reputation. Historians can come and
consult the same sources, and prove me wrong.
 If you choose to call yourself  an archaeologist, you may be competent or
not, professional or amateur, it is relatively unimportant, unless you start
to dig.
Then it is a different matter. Excavation destroys evidence, whether it is
done well or badly, so it has  to be done right: we don't get second chances.
Jay did not claim to be a professional historian. He said that he should be
"in part a historian".  I think a good historian should be in part an
archaeologist, (i.e. take into account physical as well as documentary
evidence) or he will not be a good enough historian.
Fran Kemmish