A publication of the Archaeological Institute of America
Before digging a site, archaeologists always create a site map. This map
will be used to plan digging and surveying and to record the location of
Prior to surveying and excavation, archaeologists abitrarily establish a
reference point that all depths will be measured in relation to. This is
called the "datum point." Another reference point is selected to help
locate features on a horizontal plane. On a north/south oriented map where
N, S, E, and W stand for north, south, east, and west, that point is
labeled N0E0. So when you see something labeled N40 E35, you know that you
are 40 meters (since we dig in meters and not feet) north of N0E0 and 35
meters east of N0E0. The excavation squares are labeled by their
southwestern corner. All this does is allow archaeologists to better place
them on the site map.
An excavation square is called by several names. The two most common names
for this planed hole are "trench" and "unit." Most archaeologists trained
to work outside of America call the excavation hole a "trench" while
archaeologists who work in America tend to call it a "unit." Of
course, to complicate matters, we at the Lott house call our holes
trenches. Either way, it refers to the regular area that one is working in.
Archaeologists choose whatever size unit best fits each specific site. At
the Lott House site our trenches are 2 meters by 2 meters square.
The layers within an excavation hole are also labeled differently by
archaeologists around the world. We call these different strata of dirt
within the trench "units." However, those who call their trenches "units"
call the interior strata "layers." It gets a bit confusing, so from this
point on, just remember that for our purposes, the excavation holes are
called "trenches" and named by their distance from the datum point, and our
interior strata are called "units."
Finally, the term "scarp" is used to describe the walls of the trench,
which are really a vertical cross section of many different horizontal
layers. When scarps are cleaned--scraped and made level--the soil and
artifacts collected must be analyzed separately as they no doubt come not
from one discreet horizontal layer, but from many different layers
representing different periods of time.
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