Michael Laronche raises an important methodological issue in relation to
surface evidence and abandonment:
 
>My question is this, methodologicaly speaking is it possible to
>have an above ground stratigraphy related to artifacts, and if so how much
>can one rely on it?  For instance, there is probably little stratigraphic
>information to be gained from a stock pile of iron since it was probably 
>stacked all at once.  Meanwhile, it is obvious that the same stockpile
>yields perfectly good spatial data on a horizontal plane.  On the other
>hand, how much reliance can one put on a piece of stoneware resting over a
>medicine bottle on the surface?
 
I think the question is not so much whether the stratigraphic evidence in 
the examples Michael  used is "reliable," but rather whether it is
meaningful and will contribute to his interpretation of what is going on at
the site.  The piece of stoneware resting on the medicine bottle was most 
likely deposited in its present location more recently than the bottle, but
that could have happened last year or last week (or last century).  It
won't be possible to tell which was discarded first on the basis of their 
relationship on the surface.
 
But there are some advantages to having a surface component on the site.  
One possibility would be to consider the entire surface assemblage as an
analytical unit, at least in one stage of the analysis.  While it may be
the result of a combination of abandonment activities and natural processes
such as erosion, it's formation represents one of the latest processes to 
occur at the site.
 
Another possibility might be to carefully compare surface and subsurface
recoveries from the same locations.  This would require careful surface
collection within the excavation units; in other words, not doing the
surface collection first, or delineating the units first and surface
collecting them as the initial step of the excavation.  Comparison of
surface artifacts with artifacts from the topsoil might be instructive.  
Also I would keep an eye out during analysis for cross-mends between
subsurface and surface contexts.
 
There may be some useful parrallels in the literature on interpretation of
plowzone sites, as well as some of the ethnographic research on spatial
aspects of settlement (Binford, Yellen, etc.).
 
Lauren Cook
Boston Affiliates