Appendix B: Tile Function Analysis
The following study includes a summary of items analyzed from the 1981 through 1987 excavations. It is augmented with sample drawings. Of the 426 whole or large fragments of fired adobe tiles analyzed, only 22 show evidence of 2-course tile layering. These 22 items appeared as either two tiles mortared together, as shown in Figure 9.13 (Tile 4432, item FG-81-4432, from I-2-3; CFB 8-3-86 Sheet 3);
Figure 9.13 Tile No. FG-81-4432 from Field I, Unit 2, Locus 3 showing example of two tiles mortared together. Fort Guijarros Structural Report, CFB 8-30-86, Sheet 3.
as tiles with mortar on both sides, or as tiles with mortar on one side which showed impressions of mating tiles as in Figure 9.14 (item FG-I-1-WB-2, Tile 18; CFB 8-16-86 Sheet 1). While this is not conclusive evidence of 2-course tile coverage over the entire fort parapet wall, it suggests this method of tile covering of the structure was used. For the purpose of this publication, tiles are made of molded adobe clay kiln-fired to a brick-red outer surface with various areas of the core appearing black from incomplete firing. Tile thickness of the tiles is generally 5 cm ±1 cm.
Figure 9.14 Tile No. FG-81-180 from Field I, Unit 1, WB (west balk), Locus 2 showing example of three-layer plaster, troweled over top and one edge.
Spanish records indicate that 40,000 tiles were ordered for the construction
of Fort Guijarros. It is here estimated that double-tiling the fort consisting
of 12 merlons and associated embrasures would require 20,000 tiles. Single-tiling
the esplanade would require 5000 tiles, while single-tiling the 4000 square
feet of building walls and floors would require 7000 tiles. The total
number of tiles used would be 32,000 12-by-12 inch tiles, or using a mix
of 12-by12, 8-by-12, and 8-by-16 inch tiles, it is reasonable that Fort
Guijarros would have contained 40,000 tiles.
Figure 9.15 Spanish Fort Construction.
Figure 9.16 Possible Fort Guijarros Construction.
Figure 9.17 Tile No. FG-81-23 from Field I, Unit 2, Locus 2 showing composite of tile and mortar.
Figure 9.18 Tile No. FG-81-13857 from Field I, Unit 1, Locus 4 showing composite of tile and mortar.
Figure 9.19 Tile No. FG-81-13875 from Field I, Unit and Locus not identified, showing composite of tile and mortar.
In some cases mortar impressions indicate tiles were interfaced with cobblestones,
and in a few cases, impressions indicate that tiles were mortared to unfired
adobe or compacted earth. Cobblestone impressions could be those of the
core wall, while adobe and compacted earth could indicate the interior
of the parapet structure of merlons between cannon ports. Many of the
tiles analyzed were too damaged by tide water to establish to what they
were originally affixed; only size could be determined, and in many cases
only the thickness of the tile was measurable.
Figure 9.20 Trapezoidal Tiles 43, 130, and 552.
These do not include the 11 triangular tiles of varying sizes with one beveled side (Figures 9.21, 9.22, and 9.23).
Figure 9.21 Tiles of varying sizes.
Figure 9.22 Tiles of varying sizes.
Figure 9.23 Tiles of varying sizes.
It is not known for what purpose these triangular beveled tiles were
made. They are quite similar to one another and are apparently broken
from a whole tile and beveled for a particular purpose. Several tiles
were found that indicated they had been broken to fit a certain construction
or repair situation as mortar was found on the broken edges. The irregularities
of cobblestone construction would make this a requirement when sheathing
the structure with tile.
Figure 9.24 Typical example of thicker tile.
Figure 9.25 Sketches of tiles with doodling.
Figure 9.26 Two examples of tiles with doodling. Fort
Guijarros Museum Foundation Photo Collection, P:94-1166 and P:95-1698.
Wood Fragments and Other Materials
A number of wood fragments were found and analyzed. Of 583 fragments,
564 were redwood. While they are too small to relate to any original purpose
(between 0.1 and 9 cm), it is believed that the redwood is probably from
such original construction as the reported timber beams and planking that
made up the esplanade deck upon which the 9-pound cannons rolled.