Tubac Poston House Foundation Results

Excavation Results (Deni Seymour)

A complex sequence of construction is indicated for the lot. This sequence seems to begin in the Spanish colonial period and extends into modern
times, when the lot was used as a dump. A small prehistoric scatter is also indicated but nothing on the order of a habitation site. No features
specifically related to the prehistoric period were encountered.

The large rectangular outline of a building foundation (shown in photo above) is actually a complex series of building and refurbishing episodes
where foundations were added, modified, and removed. This sequence of construction is discussed in a separate section (see below).

The high density of historic artifacts results from this portion of the lot being used for dumping household trash (ash, charcoal, fire-cracked rock,
pottery, glass, personal items of adornment [including jewelry], combs, coins, bottle caps, egg shells, faunal bone, construction debris [including nails,
wood, concrete, bricks, and stucco]) and also seemingly for discarding school supplies (chalk, pencils, marbles) and business debris (especially car
parts including shock absorbers). Artifacts, faunal bone, ash, and fire-cracked rocks were dense in this area indicating that household debris was one
of the primary sources of material. Artifacts were found on the floor and fill of the building suggesting that the abandoned rooms were used as a
repository. Pits were also excavated into which trash was placed. One of these underlies the easternmost wall and post-dates 1930, indicating that this
final wall was constructed fairly late. Two other pits cut the north and south walls, respectively, and seem to be filled with relatively modern trash.
The northern pit contained a plastic gallon jug, cinderblocks, bricks, and a household fuse. The southern pit was filled with automobile-related debris
including a head gasket, a hubcap, and a window crank. Many smaller pits intrude into the floor and fill of the building indicating smaller dumping
episodes. Given this, it is assumed that very little of the artifactual material recovered relates to the actual use of the structures. The density and
diversity of trash added to this lot through time obscures the original building-related assemblages.

Many later features intrude into the buildings. The base to what was once a large wooden cross, known to date at least as early as the 1940s, intrudes
into Unit 3. The cross itself was removed by the current landowner and was placed in a pile of debris at the north edge of the ridge. Two square posts
that were probably railroad ties are located in Unit 5. These were set upright into the ground, perhaps serving a fence posts. Several smaller round
postholes are visible in the floor; some still contain wood from their wood posts.

The north arrow points to a cluster of stacked rocks in mortar that have fallen
on their side adjacent to the Spanish colonial foundation. This is not wall fall
because the wall was made of adobe, not rocks. Rather this probably
represents a patch to the lower adobe wall that may have been damaged by
salt and water erosion, perhaps during years of neglect when the structure was
abandoned. Many modern and historic adobes exhibit this type of patchwork
in areas where the lower wall has been eroded. There are two places along
this wall and two along the southern wall where this type of patchwork seems
to have been used to stablize the wall. Interestingly, this patchwork suggests
that if this was a covered building this was on the outside of the building at
one time, and that more of the Spanish-colonial structure would have been
situated to the north. This is suggested because if the building remained
roofed the lower wall would not likely have eroded this way. If this was a wing
wall this type of erosion might have occurred on either or both sides of the
wall, but given the the prevailing wind and rain comes from the southwest it is
probably reasonable to expect that this side would have experienced greater
damage than the north side of the wall.

This English Transfer ware was found in the profile, under the east wall. This means that this part of the foundation dates later than this
(unless roots and rodents carried it there but not likely). Given this, we can say that the south and east wall was built late, while the
northern wall may have been built earlier, with the earlier foundations being incorporated into the later construction, as is typical in
Tubac. For this reason it is thought that the north foundation is from the Spanish colonial period. We had to cut the walls to determine
this for sure. The north and south walls are already cut by intrusive pits so we used those areas to breach the wall.

Profile of Bank Cut (Deni Seymour)

Sometime in the past cultural deposits in the area of the foundation were cut by a now gravel-covered acess drive and parking area in the south central
portion of the lot. This provided a cut bank or profile face along the west side of the drive that was bordered by bricks, railroad ties, and rocks. These
bordering materials were removed along with excess dirt that had been used as fill behind the border and the profile was faced to obtain and idea of
the cultural stratigraphy. What became apparent is that there are a series of additional features and intrusions, with sterile (pre-cultural) clearly visible
in the base of the trench. While there is insufficient time to investigate all of the features the profile shown below provides documentation of the more
varied activity. The largest feature is a pit with dark fill and artifacts from the 1930s. This is important because it shows that this portion of the foundation
post-dates the 1930s and accounts for its different character. Changes in the nature of the foundation suggest many different building and add-on
episodes, as is characteristic of Tubac. This also suggests that major land-modification activities have taken place on this lot, and so only a portion of the
earliest historic foundation is preserved. Pit-looking features shown in the profile may be tree wells, post holes, and, potentially, prehistoric features
although there is insufficient time to investigate these and other than the large pit there are no artifacts in them to suggest and age. Rodent holes
throughout portions of the profile and in the soft fill of these features indicates that artifacts may be moving from deposit to deposit.

Profile drawn by Jeremy Moss and Nicole Arendt and drafted by Nicole Arendt

Stratigraphic Sequence

The overburden was much thinner than we initially thought, which allowed us to reach the floor in all six excavation units. Fill depth
decreased from west to east, owing to the natural gradient of the landform and also because the ground surface nearest the house was less
disturbed.

The stratigraphic sequence is fairly consistent across the entire feature indicating that once the rooms were finaly abandoned they were filled
with relatively late trash.

Stratum 1 is the loose wind-blown and water-lain brown sediments.

Stratum 2 is dark gray clayey and oily fill, rich with construction debris, ash, charcoal, and artifacts. This is post-occupational fill deposited
here from throughout the community. Artifacts suggest that the most intensive period of dumping was in the 20th century as car parts, modern
ceramics, metal, paint, and construction debris are found in floor contact.

Statum 3 is represented by the false floor (or later compacted surface) in Units 5 and 6. This is about 10 cm higher than the real floor and may
represent a use surface after the structure fell out of its original use. This does not continue across the entire floor because of disturbance and
perhaps also owing to differing ages and uses of the various rooms.

Stratum 4 is the floor which seems to be compacted clay that is nothing more than the underlying natural clay stratum. This surface is beige
but is mottled owing to disturbance and use. Postholes and intrusive pits cut through many areas of this uneven surface. The floor is best
preserved to the west. The floor is cut by later features and has been severely damaged, presumably from water saturation and subsidence, on
the east.

The walls are also best preserved on the west side. Adobe bricks are preserved over the foundations on the west side of the work area. Their
absence on the east side and the lack of abundant (but intermittent) adobe brick debris in the fill suggests that many of the bricks were
scavenged for use in other buildings. Adobe brick fragments in the fill were noted mostly on the west side where everything is better
preserved, having been closer to the standing Poston structure and also buried under thicker fill.