One of the reasons for the ability of the Brits to do meaningful horizontal
excavations of large areas, while the US standard of turning a site into Swiss
cheese with many small vertical test units as the norm lies partly in the
widespread use of geophysics prior to excavation in the UK and elsewhere in Europe
and American trust in the "validity" of statistical sampling. The advantage
of geophysics is that more complete vertical (and horizontal) information can
be gleaned from a site without disrupting the stratigraphy.  We in the US are
gradually increasing our reliance on geophysics.  I hope that those of you
attending the Society for California Archaeology meetings this year are able to
take Lew Somers' workshop on the subject.  These methods are particularly useful
to historical archaeologists.
Bob Hoover