Excavations at the Alamo Shrine [page 24]In Unit 5, a small, shallow fireplace which lay on the brown clay surface close to the building foundation was uncovered. No hearth stones or artifacts were associated, but there was a thin deposit of charcoal and ash, and heat-colored red clay in a semicircular pattern. Apparently the original fireplace was a larger subcircular pattern which was cut through when the builders dug the footing trench into the ground surface.
In Unit 8, found lying upon the brown clay mission-period ground surface, were cow or bison bones and two chert arrow points. The points were small triangular types characteristic of those found at other missions in south Texas and northern Coahuila and are evidently associated with the mission Indians (Hester 1977). Chipped stone tools and some chipping debris were also found in other excavation units at this same level.
Almost coincidental with the beginning of the reddish brown clay, a heavy deposit of river cobbles was encountered (Fig. 8). The first impression was that perhaps the stones were associated with the earlier church construction that had collapsed. However, since the stones lay in sterile clay well below the mission period ground surface, they may represent natural deposit.
Roughly 50 cm below the dark brown clay surface and lying just below the reddish brown clay, a level of grayish brown granulated sterile caliche was encountered. This deposit is about 15 cm in depth and rests upon hard white basal caliche. This is the basal footing upon which the church foundation was set. In other words, the foundation footing trench had been dug approximately 65 cm below the mission ground surface to reach suitable stable caliche base.
The term caliche is of Spanish origin, from Latin calx, meaning lime, and is commonly applied in North America to a porous, earthy calcium carbonate containing impurities of soil, sand, and gravel, which occurs widely at the surface or at shallow depth in the soil or penetrating porous rock outcrops in the zone of weathering (Price 1933:500). In a broad sense, caliche is used as a generic term for all types of soil-mineral accumulations. Here we will be referring to calcareous caliche, the accumulating of calcium carbonate in the soil processes which occur abundantly in south Texas.
During the excavations, a section of backfilled palisade trench dating to the famous battle of 1836 was uncovered and tested. This was first discovered in Unit 8, which was dug against the building wall and followed by means of Units 10 and 11 extending out from the wall (Figs. 10, 11).
The old backfilled trench was first noted as a slight depression and soil color change within the upper level white caliche. The trench began about 65 cm out from the building wall and extended southwest (250° magnetic) to as far as the old sidewalk curb, located three meters from the wall (Figs. 3, 11). The trench did not follow beyond the curb since that was the area of the old street and was very much disturbed. The trench averaged ca. 70 cm in width and ca. 45 cm in