The "metric" approach to archaeology is still a standard method in a
     fair percentage of the fieldwork in Texas, New Mexico, and Arizona,
     although there are a few who attempt to dig by strats or by a hybrid
     system of strats and metric levels.  10 cm is the standard, but larger
     intervals are used "where there's no stratigraphy."  Part of the
     problem is that much of southwestern fieldwork is considered
     "testing," and utilizes 1m x 1m units, or at best 2m x 2m units.  Even
     large area excavations might be set up as a series of small "test"
     units.
 
     Jake.