Archaeology Update — New Excavation Unit Opened at North Side of the Church

Kristi Nichols, Director of Archaeology, Collections and Historical Research
January 7, 2020

During the week of December 16, archaeologists from the University of Texas at San Antonio’s Center for Archaeological Research (UTSA-CAR) worked on archaeology monitoring as well as shovel testing and excavations in several of the areas around the perimeter of Alamo Plaza. In the northern area of the Plaza, two areas were active, with shovel testing and monitoring occurring to determine if there were any significant finds. It appears that this area is similar to much of the rest of the perimeter, containing caliche base placed during previous improvements. No features or artifacts were encountered in this area. Placement of bollards began at the northwest corner of the Plaza.

In addition to the work on the north side of Plaza, UTSA-CAR completed additional investigations of a feature that had been encountered early in the project. The feature consisted of an alignment of limestone rock, and likely represents a portion of the foundation of a structure that appears on the 1885 Sanborn Fire Insurance Map as a saloon and boarding house. Previous damage to the foundation is evident by the presence of an iron utility line that cut through the center of the feature. The base of the foundation was found and the archaeologists were able to document the remnants of the foundation portion uncovered.

UTSA-CAR broke for the holiday break on December 20th, although some archaeological monitoring occurred on December 26 and 27 in Area 6, located on the north side of the Plaza. No significant archaeological deposits or features were encountered. Work is progressing with the installation of the steel bollards in several of the areas around the Plaza.

Excavations conducted by Raba Kistner Archaeologists for the week of December 16, 2019, focused on excavation unit 1–3 and unit 7. Excavations for unit 1 continued with the completion of Level 3 (15–19 inches below datum) (Figure 1) and Level 4 (19–23 inches below datum). Deposits within the northern portion of the unit continued to be mixed as a result of the 1995 excavations by UTSA-CAR; however, once excavations cleared the disturbance from the existing utilities, archaeologists observed intact soil deposits in the southern boundary of the unit approximately 5.9 inches wide.

A review of the 1995 excavation report indicates that past excavation measured between 59–66 inches wide (scale on provided report is unclear). As such, excavations for the intact southern portion of the unit will be excavated and screened separately from the disturbed northern portion of the unit. Cultural materials recovered from the disturbed northern portion of unit 1 this week included brick fragments, mortar/plaster fragments, sandstone fragments, nails (square and wire), unidentifiable metal fragments, slag, ceramic sherds (white earthenware, lead glaze, and ironstone), lithic debitage, charcoal, container glass fragments (clear, brown, olive, and aqua), charcoal fragments, and a shell button. Cultural materials recovered from the intact southern portion of unit 1 this week include lead glazed ceramic sherds, container glass fragments (clear and brown), charcoal fragments, and building material fragments (brick, mortar, and plaster).

By the end of the week, the bottom of the black plastic placed against the exterior South Transept wall during the 1995 investigations was uncovered. The plastic lines the vertical wall of the wall foundation and levels out horizontally at 23 inches below datum, extending for approximately 23 inches from the Church wall before terminating (Figure 2). Two additional existing utilities running east/west were also uncovered at the bottom of Level 4, approximately 23 inches north of the southern boundary profile.

Exploratory excavations for unit 2 were minimal this week, with the beginning of Level 4 (19–23 inches below datum) (Figure 3); however, after the second day of excavations, archaeologists working in the unit began experiencing symptoms that may have been associated with mold or other contaminants within the unit. Excavations for unit 2 were put on hold by Tuesday, December 17th, and the unit was sealed up until testing could be conducted to determine if any health hazards were present. The minimal excavations completed for unit 2 this week identified large conglomerates of asphalt material within the level, as well as slag, mortar fragments, and plaster fragments.

Closing of excavations
Figure 1. Closing of Level 3 (15–19 inches below datum) excavations for unit 1, facing west.
Closing of excavations
Figure 2. Closing of Level 4 (19–23 inches below datum) excavations for unit 1, facing north.
Beginning of excavation in church
Figure 3. Beginning of Level 4 (19–23 inches below datum) excavations for unit 2, facing south.

Excavations for unit 3 continued this week with the completion of Level 9 (35–39 inches below datum), Level 10 (39–43 inches below datum) (Figure 4), and the beginning of Level 11 (43–47 inches below datum). All of Level 9 and the upper portions of Level 10 were composed of a compacted caliche floor. Cultural materials recovered from the caliche floor were minimal, limited to one Spanish Colonial ceramic sherd, and less than five lithic flakes.

The lower portion of Level 10 and all of Level 11 consisted of a dark silty clay matrix that contained Spanish Colonial ceramics, snail shell, fire cracked rock, charcoal fragments, lithic materials, and a possible bone pipe stem. Excavations extending downward continue to reveal the foundation of the Church wall.

On December 17, 2019, excavations began for unit 7. Unit 7 is a 6x6 foot unit positioned within the interior northwestern corner of the Temporary Sacristy. Excavation began with Level 1 (6–11 inches below datum). Cultural materials recovered from unit 2 this week included large volumes of construction material (limestone, red brick, mortar, and plaster), ferrous wire nails, container glass fragments (clear, brown, and olive), mechanically crushed chert, charcoal fragments, snail shell, and Spanish Colonial sherds.

Additionally, a significant amount of intact plaster with red pigment was documented along the western unit profile wall (the western wall of the Temporary Sacristy). The plaster is located between 7–15 inches north of the southern unit boundary, approximately 5–7 inches below datum (Figure 5). The Alamo Preservationist examined the find and applied a protective sealant to the decoration.

By the end of Level 1, a limestone alignment began to manifest along the base of the northern wall of the Church (Figure 6). The alignment ranges from 6 to 9 inches below datum and extends 11 to 15 inches from the northern wall, with narrower measurements towards the eastern end of the unit. Close examination of the feature determined that the alignment represents the original northern Church wall foundation. The present-day northern wall of the Temporary Sacristy is a reconstruction, erected during the U.S. Military occupation of the site. The exposed foundation is slightly offset from the reconstructed wall, set in a west-southwest projection.

Excavations in Alamo Church
Figure 4. Closing excavations for Level 10 (39–43 inches below datum), unit 3, facing west.
Excavation in Alamo Church
Figure 5. Closing excavations for Level 1 (6–11 inches below datum), unit 7, facing west.
Plaster with red pigment
Figure 6. Plaster with red pigment documented along the western wall of the Temporary Sacristy, within unit 7 facing west. Note: The white substance surrounding the edges of the painted plaster is a preserving solvent applied by the Alamo Preservationist after its discovery.

For the Raba Kistner archaeology team, no excavations occurred during the week of December 23rd. The team returned the week of December 30th. Excavations resumed on units 01, 03, and 07.

In addition, some work occurred on backfilling unit 13. Archaeological excavations conducted within unit 3 continued to reveal a dark clay that contained few artifacts. The majority of the materials encountered consisted of early colonial materials as well as Native American pottery, and chipped stone flakes. By the end of the week, excavations stopped as the archeologists had encountered the maximum depth allowable until excavations could resume inside the Church. The base of the foundation had not been encountered by 47 inches below the datum.

By the end of the week of December 30, preparations were being made to open a new unit on the north side of the Church, in the Convento Courtyard. The new unit is the partner to unit 7, and will give a view of the construction of the exterior of the north wall of the Church, in an area that is known to have been altered by the U.S. Army. Excavations will begin in this unit during the week of January 6, once all the weatherproofing measures have been taken.