Dear Todd:
 
This is not an uncommon argument about historic archaeology.  I do not want
to get into a theoretical discussion here and will not provide an extended
discussion, but one of the primary reasons its important is because there is
much that we are able to establish from the archaeological record that IS NOT
written down.  Yes, we use written records and they help greatly in our
understanding of what we are looking at, but written documents generally fail
to record many important facets of life - how people lived, what they ate,
who they interacted with in a community and why, what material culture
changes took place over time in a particular locality,  what the particular
ethnic make-up of a particular site or  community may have been, how a
commercial establishment fit into a community's social structure, how a
milling process was carried out at an industrial site, and a thousand other
questions.  Also, though the written record may touch on some subjects, it is
almost always incomplete, leaving out critical details which help us in a
better understanding of a site, a people or an industrial process.
 
One other critically important reason for historic archaeology, and one that
is not possible with prehistoric archaeology, is that in some cases we are
able to compare the historic record and the archaeological record and find
out just how close (or more often how far off) we are in our analysis of
sites.  Such comparisons allow us to refine our future assessments of data
and, hopefully, get a little more accurate in our conclusions.
 
I'm sure others will enlighten you even further and in a more in-depth
manner, but this provides some of the basic reasons.
 
Mike Polk
Sagebrush Archaeological Consultants\
Ogden, Utah