Archaeology Field Report on the Search for Fort Guijarros

Figure 8.23 View west of wall (Strata V). The first layer of revestimento (glacis) cobbles were removed from Strata III. Fort Guijarros Museum Foundation Photo Collection, P:81-7272.

Internal wall components: Strata II, III, IV, V

The 1981 archaeological investigation cut a cross-section through the contrafuera (See figure 8.20). Thousands of 3.96- to 15.84-inch rounded cobbles were heaped against the first six tiers of Strata I. Two distinct layers of these cobbles have been labeled Strata II and III. Above Strata III cobbles was a layer of tan sand (Strata IV) and another mass of small cobblestones (Strata V). The battery face of Fort Guijarros formed a glacis of cobblestones from the top of Tier 12 of Strata I sloped down to the beach, which Spanish engineers called the revestimiento.

As the Spanish construction crew elevated the tiers of Strata I, they also filled the interior side with alternating levels of sand and large cobbles. The first level is clear white beach sand, believed to have served to level the surface above the beach at Tier 2. To the right of Strata I in Figure 8.8, layers of large cobblestones are recorded at Tiers 2, 3, and 6, which were better understood during the Field VIII investigation exposing the top layer a full 32.81 feet west of the foundation core. Supported by contrafuera on each side of the core wall, beds of large cobbles sandwiched sand levels to form a strong foundation for the cannon decks and heavy masonry merlones.

The archaeological remains of the merlones exist as collapsed rubble on top of the sloping glacis of the contrafuera. Depicted in Figure 8.20 as Stratum VI, VII, and VIII, the architectural rubble posed a puzzle for archaeological interpretation that required treating each masonry fragment as a puzzle piece to be analyzed for interpretive reconstruction (Buchanan 1996; See figure 8.21) which depended on that analysis and correlation to engineering directions posed by de Lucuze.
The current hypothesis proposes that scavengers removed critical cobbles and tile. Once weakened, the yellow sand fill behind the merlón would have poured down the cobblestone slope covering the beach below. The tile masonry would have collapsed inward, or floated over the sand. Scavengers would have further broken the tile mass, but the sudden deposition of the merlón masonry protected more intact architecture (May 1996:13).

Strata VI

Strata VI was a yellow-tan sand identical to the yellow-tan fill sand on the interior side of Strata I. This fill appears to have leaked through or across Strata I and poured down to cover Strata V cobbles. No artifacts were recovered in Strata VI, indicating the sand was deposited on Strata V during an episode when no one occupied the area. This deposition may have occurred after Mexican demilitarization in 1835, when the authorities no longer maintained the battery.
A mass of cobbles half way down the slope of Strata VI may have been dislodged from Strata I or pushed from higher elevation of Strata V. These cobbles in Strata VI appear larger than those observed in Strata V. These cobbles may reflect decomposition of the battery face, as well as interior fill sand leakage.

Strata VII

A massive deposit of slightly yellowed sand completely covered Strata VI and spread east beyond the Field I excavation. A single white plate sherd with a Pearl Ware glaze recovered from screening Strata VII provided the only evidence to date deposition. The general lack of artifacts in Strata VII indicates the deposition did not coincide with occupation of the site, but occurred after the 1840s. The length of Strata VII, a full 19.69 feet east of Strata I, indicates a powerful single episode of dry transport of material. This depositional process would be similar to a landslide.

Comparison of Strata VI and VII soils suggest two distinct episodes of architectural collapse. Strata VI dimensions indicate slow leakage, while Strata VII dimensions indicate a sudden and powerful collapse of a massive structure filled with loose sand (Figure 8.24).

Figure 8.24 This photograph shows a collapse episode of Strata VII and VIII rubble, as well as broken tiles with plaster. They tumbled in at different angles on top of yellow sand (Strata VI) and Strata V cobblestone glacis. Fort Guijarros Museum Foundation Photo Collection, P:81-7257.

Strata VIII

A random mound of large cobbles mixed with dissolved and re-compacted reddish-tan adobe block, shattered fragments of whitewashed cement mortar, and fragments of fired adobe tile formed the upper portion of Strata VIII as it lay directly on top of Stratum V, VI, and VII (See figure 8.20). The cobbles correlate directly with cobbles in Strata I, but no black shell midden mortar was recovered in Strata VIII.

Directly on top of the mound of cobbles lay a partially dissolved stack of unfired adobe blocks, yellow-tan sand mixed with high quantities of fired tile chips and whitewashed cement mortar fragments, and smaller cobbles. Patches of sea grass, also known as eel grass, and beach sand were interspersed among the cobbles. See grass lives in brackish water estuaries, such as would have been found 1 to 2 miles north at the confluence of the San Diego River and San Diego Bay. The species does not exist near the more saline mouth of the harbor near Ballast Point. Heavy discharge of the San Diego River dislodges eelgrass flotsam and transports the grass along with driftwood toward the mouth of the bay. The eelgrass in Strata VIII represents an episode of heavy San Diego River discharge.

Loose clean beach sand is not indicative of estuary environments. The San Diego River and Sweetwater River six miles to the east transport organic sediments that decompose in estuarine eel grass and rocky settings. The result is a more loamy sand than found closer to littoral beaches. Heavy wave action and surf scouring cleans littoral sand of loamy sediments, leaving white beach sand.

Removal of the unfired adobe and fill sand in Strata VIII revealed a tumbled scree of dozens of fired adobe tiles, large sections of whitewashed mortar, and reconstituted unfired adobe. A few large cobbles were mixed among the fired tile mass. The volume of fired tiles increased on the western half of Field I. Large quantities of sea grass matting and loose beach sand were mixed among the fired adobe tiles in Strata VIII.

To obtain a sample of fired adobe tiles and whitewashed cement mortar for architectural interpretation, all architectural remains in Units 1, 2, 3, and Balk Units 1W, 2W, 3W were recovered. The analysis of these tiles is reported elsewhere (Buchanan 1996).

All architectural remains exposed in Units 4, 5, 6 and Balk Units 1S, 2S, 3S, 4W, 5W, 6W, 1SW, 2SW, 3SW were left in situ for future scientific inquiry. These were mapped, photographed, and designated elevations. A re-examination of Field I in 1987 re-mapped these tiles (Buchanan 2005).

Strata VIII represents the final collapse episode for the merlones. The presence of sea grass and patches of loose beach sand provide clues to the process of collapse. Weakened by Strata VI leakage and massive Strata VII landslide, high ocean surf coincident with heavy San Diego River discharge would account for the sea grass and beach sand. A wet winter storm probably caused the final collapse of the merlones at Fort Guijarros. The association of a Pearl Ware sherd suggests this occurred mid-19th century.

As a footnote to the archaeology at Field I, the bulk of the architectural samples recovered in 1981 and 1982 at Fields I and III were returned to Field I in 1987. These were placed in the northeast corner in line with the former backhoe trench. The returned specimens included hundreds of small fired tile chips and fragments, paper sacks of whitewashed mortar, and a dozen or so complete tiles. The area was marked with 1987 copper U.S. coins and two modern machine-made bottles. These specimens were determined not necessary for long-term scientific research.

Field II: Second set of architectural data

The 1982 field season designed an excavation strategy to obtain improved Fort Guijarros architectural information. Tangent to the West End of Field I, Field II measured 9.84 feet by 9.84 feet. An asphalt road installed by the U.S. Navy in December 1981 had restricted the north boundary of the sample area. A concrete deposit installed as a base for the 1975 boulder rip-rap sea wall constricted investigation and limited archaeological access to the south.

The east side of Field II was a southern extension of Strata I from Field I. All of Strata I was left in place at Field II. At 0.1-0.3 inches, large chunks of concrete rubble blocked deeper excavation. Soil in Field II coincided with post 1924 U.S. Army deposition of the concrete rubble. Excavation of Field II terminated at the rubble.

Field III: Test for activities outside the wall

Simultaneous with the Field II investigation, the 1982 field season designed an excavation strategy to search for Spanish architecture or occupation features on the beach east of the Fort Guijarros glacis (Figures 8.25 and 8.26). Anticipated activities would have been occupation and refuse deposits, metal and carpentry workshop activities, livestock agriculture, and boatyard activities associated with the Spanish flatboat that transported the fired tile, lumber, and cement from the Presidio.

Figure 8.25 A Birdseye View of Fort Guijarros. Jay Wegter. 1990. This hypothetical view of Fort Guijarros shows the target area of Field III. The goal was to test for behavioral activities on or around the glacis and beach beyond the Fort. Instead, an American whaling camp from a much later time period was encountered.

Figure 8.26 Soldiers at Fort Guijarros by Jay Wegter. 1990. This hypothetical interpretation shows how the outside of the Fort may have appeared. Note the sloping walls of the exterior of the Fort.

Field III measured 16.4 feet (north-south) by 29.53 feet (west-east) (Figure 8.27). The vast majority of Field III consisted of extensions of Stratum X (civilian shore whaling) and Strata XI and XII (U.S. Army) earth fill (May 1985:1-24; 1986:73-90; 1996:41-58). At the bottom, Stratum VIII rubble from Fort Guijarros scattered widely over sterile beach sand. Sample test pits in the beach sand encountered seawater but no artifacts.

Figure 8.27 General unit configuration for Field I and Field III, excerpted from C. Fred Buchanan’s Key Map–Field I & III. The reason the two grids are not in alignment is that nearby Navy equipment interfered with magnetic readings during the first ten years of the investigations.

Field III exhibited intensive wave scouring at Stratum VIII. As much as 2.62 feet of sterile beach sand separated individual tiles. All the tiles were eroded by wave action, but fragments of whitewashed cement mortar were also present in the sand. All the fired adobe tiles were recovered for analysis, but most were returned to Field I in 1987 following analysis.

Field III demonstrated no Spanish architecture or other activities east of the contrafuera (revestimento) and glacis on Ballast Point. Evidence of activities that had occurred there have been scoured away by ocean surf and heavy discharge of the San Diego River.

Field IV

The 1983 field season tested hypotheses regarding the boundaries of archaeological deposits associated with Spanish and Mexican soldier occupation inside the wall of Fort Guijarros. Analysis of elevation contour lines on the 1867 U.S. Army Corps of Engineers map of Ballast Point (See figure 8.1) revealed a man-made graded cut in the Point Loma hillside, a large level pad behind the portion of Fort Guijarros exposed in 1981, and a south berm along Ballast Point that linked with the fort. The Field IV test was placed north of the 1981 asphalt road and on the south face of the 1873 Fort San Diego and 1898 U.S. Army Battery Wilkeson (Figure 8.28). The purpose was to learn how the Spanish used the area behind the wall.

Figure 8.28 Civil Engineer Marty Byrne prepared this design for deep test pits at the request of the Navy Civil Engineer. Once approved, the Fort Guijarros Museum Foundation had to design sufficient shoring to meet the requirements of the Navy Safety Officer. The actual location of Field VI was approximately fifty feet north of Byrne’s proposal in order to avoid interfering with Navy operations. The Field V pit was more to the left once the Navy demolished Building 251 (“The Dolphin Club”).

The Base Civil Engineer required an engineering drawing prepared to design safe excavation into the earth fill of Battery Wilkeson (Figure 8.28). Civil Engineer Marty Byrne of Graves Engineering prepared the drawing. A mechanical bobcat skip loader cut and shaped the excavation site. Heavy timber shoring locked the 20-foot-high cut in place and shored the excavation below 4 feet, in accordance with safety laws (Figure 8.29).

Figure 8.29 This view shows the heavy shoring necessary to create a safe working environment deep below the 20th-century fill that covers the mid-19th-century to late 18th-century trash deposits behind the walls of Fort Guijarros in Field IV. Fort Guijarros Museum Foundation Photo Collection, P:84-636

A hand-crane erected on the wood shoring hauled metal buckets of soil from the excavation (Figure 8.30). All soil was screened through 1/4-inch mesh, but very few artifacts were recovered in the first 6.56 feet. A single amber glass medicine bottle dated the first 4.92 feet to after 1898.

Figure 8.30 Top: View of Andrea McKee at the wooden crane used to lower and raise buckets in Fields IV, V, VI, and VII. Bottom: Composite using 1943 aerial photograph of United States Army Fort Rosecrans Coast Artillery Battery Wilkeson with Donaldson’s Fort Guijarros postulated location as an overlay to show location of Field IV, V, and VII excavation areas indicated by red circle. Fort Guijarros Museum Foundation Photo Collection, P:86-7181 and P:86-1033-16.

A large cast concrete drain from Lt. Weeden’s 1873-1874 U.S. Army Corps of Engineers construction of Fort San Diego appeared at 6.56 feet below the existing parking surface. The drain feature was left in situ for future scientific investigation. The base of the drain dated the surface of the ground to 1874. Directly below the base of the 1873-1874 drain, a bed of alluvial gravel covered the entire surface. This 7.92-inch-thick deposit (Locus 7) is believed to have been installed by Lt. Weeden to form a base for the drain installation. A single glass wall sherd of a 1860s schnapps bottle supports this interpretation.

Buried anaerobic pond clay deposit with Spanish trash.

Under the Locus 7 gravel deposit, a thin layer of wet, fine, greasy micaceous gray clay with black patches of decomposed woody vegetation and dark seeds formed Locus 8. The clay is similar to estuarine marsh ponds. A few marine shells and one fragment of a water-worn Spanish roof tile were embedded in the clay (Figure 8.31). Directly under the clay deposit, a wet gray sand of medium to coarse grains mixed with marine shell, Spanish tile, mortar fragments, and rock fragments formed Locus 9. The sand in Locus 9 was coarser than the surrounding beach sand. Hydraulic sorting of the Locus 9 sand indicates San Diego River deposition.

Figure 8.31 Spanish roof tile fragment. Fort Guijarros Museum Foundation Photo Collection, P:84-636.

Fort Guijarros trash feature

At a depth of 9.84 feet, a pit excavated through Locus 9 filled with a 4-to-9.84-inch-thick micaceous gray greasy clay deposit formed Locus 10. Excavation released hundreds of fine dark vegetal seeds as the water table rushed into the excavation. Sump-pumping lowered the water table in a sterile hole southwest of Locus 10.

Locus 10 comprised a trash feature associated with the occupation of Fort Guijarros. Large chunks of the micaceous gray greasy clay were removed in buckets to be water-screened through 1/16-inch window mesh and 1/64-inch geology screens. A total of 52.97 cubic feet of clay and artifacts were recovered and water-screened.

The screens yielded rusted iron lumps, Spanish tile, splintered food bone, Tivela stultorum Pismo clam shells, three sherds of a Tizon Brown Ware jar, Asian Export Porcelain cup and platter sherds from the late 18th to early 19th centuries, eight sherds of Mexican Majolica, Galera Ware, wood, leather, bone button blanks, fish bone, animal teeth, and marine shell.

Twigs, scraps of cut leather, and plant remains were placed in distilled water baths to leach out salts. Once free of salt, the vegetal fragments were dried and packaged with other vegetal remains. The cut leather scraps were treated with Carbowax for long-term preservation and are now in the temperature- and humidity-controlled Ballast Point Repository.

The Majolica included a sherd from a Monterey Polychrome soup plate, which dates from 1800 to 1835 (Figure 8.32). Also present were Puebla Blue-on-white and Aranama Tradition soup plates (1750-1835). The Asian Export Porcelain included a large basal sherd of an Export Chinese Canton Blue-on-white serving platter. The execution of the design and detail work indicates early 19th-century manufacture. Other porcelain included a hand-painted cup rim (Figure 8.32).
Upon removal of the last remains of Locus 10, test holes were excavated through sterile beach sand to the water table. Metal probes as deep as 3.28 feet confirmed the determination of sterile sand below the trash pit.

Figure 8.32 Top: This broken piece of an Aranama Polychrome Tradition soup plate is classic early 19th-century Mexican Majolica. The black accent surrounding the orange band and the green interior dots characterize this type as dating from 1800-1835. Bottom: This Chinese Canton Trade Ware serving platter fragment is a style that dates from a Manilla Galleon supply ship in the late 18th century. Both sherds were recovered in an anerobic pond clay deposit with other Spanish artifacts such as cut leather strips, food bone, and Spanish tile. Fort Guijarros Museum Foundation Photo Collection, P:96-3581 and P:95-1770.

Following the discovery of a Spanish/Mexican trash feature behind the walls of Fort Guijarros, the Fort Guijarros Museum Foundation and U.S. Navy collaborated in a long-term effort to define the extent of Spanish and Mexican behavioral activities surrounding the fort. The 1983 investigation of Field IV demonstrated the earth fill in front of 1898 U.S. Army Battery Wilkeson covered significant archaeological features associated with Fort Guijarros. The Monterey Polychrome and Canton Blue-on-white ceramic artifacts date the trash feature to the Fort Guijarros occupation between 1796 and 1835.

Field V: Test behind Building 539 Fire Station

A second investigation in 1983 tested an area 25 feet north of the northeast corner of Building 539 in search of the northern extension of Fort Guijarros architecture. This excavation was situated in direct line with the contrafuera detected at Field I. Excavation at Field V provided no evidence the portion of Fort Guijarros exposed in Field I is the north wing. At about 5.91 feet in depth, a dark brown to black soil with small rounded pebbles appeared.

Locus 2 contained Astrea undosa, Chione undatella, Haliotis ssp, Pteropurpura ssp, and Tivela stultorum marine shell. Small fish bones, small Spanish tile chips, and fragments of a Chinese brown-glazed vegetable jar dated this deposit to the 1858-1886 whaling and Chinese occupation of the Fort Guijarros site. Below Locus 2, wet beach sand with Astrea undosa and Ostrea lurida marine shell and a few splintered cattle bones formed Locus 3. Excavation to a depth of 6.56 feet at Field V failed to detect Spanish architecture or trash features.

Field VI: Test north of Field V

The 1986 investigation of Field VI searched for Spanish or Mexican residential activity areas associated with Fort Guijarros along the bay shore. This 13.12-foot-square field block was located west of the asphalt parking lot, between two existing eucalyptus trees and on the east flank of the 1898 U.S. Army Battery Wilkeson (Figure 8.33). As in the design and execution of Field IV, heavy wood shoring protected the excavation crew from a cave-in. A wooden crane served to haul out buckets of earth.

Figure 8.33 Field VIII dig crew. Unidentified person on the upper left; Jim Royle on the right. C. Fred Buchanan sits in the foreground. Fort Guijarros Museum Foundation Photo Collection, P:93-1068.

From surface to 6.89 feet, Locus 1 proved to be medium to dark brown loam mixed with automobile parts, U.S. Army glazed sewer tile, concrete, rusted metal, machine-made bottle glass, a tree stump, and a white-painted rock. The saw cut tree stump and rock were labeled Feature 1, and interpreted as a Fort Rosecrans landscape feature. The artifacts date Locus 1 to post-1902 U.S. Army Fort Rosecrans occupation. Several hard hammer flakes, bones and marine shell recovered in this deposit are secondary deposition and not associated with the U.S. Army primary occupation.

At 6.89 feet to 8.2 feet below the parking lot, Feature 2 consisted of a 0.84-to-3.96-inch-thick clay mixed with marine shell, splintered bone, and 9 Spanish tiles. Faunal analyst Paula Reynolds identified the bone as primarily donkey skull. Feature 2 may represent Spanish occupational refuse, but the density of recoveries is not significant enough for scientific study. Test holes in the sterile sand below yielded the water table at 8.86 feet deep.

Field VII

The 1983 field season placed a block of excavation units 11.48 feet (west-east) by 6.56 feet (north-south) 6.56 feet west of Field IV to make a second attempt at locating the Spanish barracks or kitchen behind Fort Guijarros. A wooden hand crane was used to haul out soil.

From surface to 3.94, Locus 1 consisted of interbedded layers of yellow and black soils mixed with occasional prehistoric fire-cracked rocks, Spanish tile, marine shell, and a small caliber rim-fire bullet shell. Locus 1 dates to the 1873-1874 construction of Fort San Diego. From 3.94 to 7.22 feet, Locus 2 consisted of a yellow-tan sand mixed with angular rocks, sandy clay, and specks of red clay tile. Eighteen fire-broken rocks, five hard hammer percussion flakes, one sherd of Tizon Brown Ware, and two pieces of red clay were scattered widely about the deposit.

At 7.22 feet, a light brown sand interbedded with mottled yellow and brown soil formed Locus 3. Mature Ostrea lurida and Astrea undosa marine shell, Spanish roof tile, and traces of decomposed wood were spread within Locus 3. From 7.22 to 8.2 feet, Locus 4 consisted of white sand mixed with angular and rounded rocks, rusted metal, Argopecten aequisulcatus, Ostrea lurida, and Chione undatella marine shell, Spanish tile fragments, splintered animal bone, and large cobbles. Locus 4 dipped in the northeast corner to 7.55 feet. From 7.38 and 7.55 to 8.2 feet, a thin layer of dark gray sand that blended to a mottled dark clay formed Locus 5. The clay and earth layer contained pieces of charcoal, organic plant matting, Spanish tile, splintered food bone, and marine shell. Locus 3 penetrated Locus 5 to 7.38 feet. At 8.3 feet, a thin light tan sand lens formed Locus 6. Hints at metal artifacts appeared as iron rust stains.

From 8.2 to 7.38 feet in depth, a Spanish trash feature of gray greasy clay, decomposed plant remains, rusted iron smears, gravel and charcoal, Spanish tile, and splintered food bone characterized Locus 7. Removed in large chunks for water-screening in 1/16-inch mesh, these organic-rich materials yielded scraps of cut leather that were desalted and treated with Carbowax. Seeds and plant remains were desalted and dried for later analysis. The anaerobic wet clay environment preserved leather and wood.

Locus 7 also yielded Monterey Polychrome Majolica from the 1800 to 1835 time period, Mexican Galera Ware, and early 19th century Canton Blue-on-white Asian Export Porcelain. Over 150 fragments of Spanish floor and roof tile were recovered, most of which exhibited erosion from immersion in water. The roof tiles provide tantalizing evidence for a Spanish building nearby. The ceramic and food remains indicate the building to be the kitchen
.
Reynolds also analyzed the food bone from Locus 7. She quantified 717 pieces of bone weighing a total of 3,862.8 grams. In comparison, the Spanish feature in Field IV yielded 1,759 bone pieces weighing 4,463.65 grams. Given the similarities and proximity of these two features, the bone samples were combined to yield 142 cattle (43%), 7 sheep (2%), 2 pig (-1%), and 1 horse (-1% ) specimens. A total of 129 or 85% were cut with cleaver and 20 (13%) exhibited knife marks. This analysis also demonstrated that 133 or 67% of the cattle bones were plate or brisket cuts, 15 (7%) were short loin (back), 12 (6%) were chuck (shoulder), and 9 (5%) were hindshank. These data indicate a high incidence of slaughtering waste on site, rather than transportation of cut meat from the Presidio five miles north.

The investigation at Field VII substantiated the presence of the Fort Guijarros military kitchen west of the artillery battery. Future investigation of larger portions of this area should reveal the barracks, kitchen, and perhaps the storehouses. The primary challenge to those investigations will be the U.S. Army fill at a depth of 8.2 to 9.84 feet which will need to be penetrated and shored prior to archaeology work.

Field VIII

The 1989 field season was designed to obtain a second sample of the contrafuera of Fort Guijarros and to obtain measurements that would resolve architectural questions regarding the composition of the merlones. This field block measured 91.86 by 16.4 feet in size. The excavation was planned for several years of work in order to maximize field measurement and provide ample time to carefully excavate the U.S. Army and shore whaling company fill layers that cover the Spanish ruins.
The excavation of Field VIII continued until October of 1995 (Figure 8.33). The field strategy for Field VIII did not involve a cross-section through the wall. The Research Design oriented removal of fill layers to expose Strata VIII, map and photograph the tiles (Figures 8.34 and 8.35). Only select specimens of architectural samples not recovered at Field I or tile art specimens were to be recovered.
Exposure of the top of the foundation core in the contrafuera measured 10.8 feet above Mean Low Low Water. The toe of the cobblestone glacis measured 26.25 to 32.81 feet away from the foundation core. The toe elevation measured 6.68 feet above Mean Low Low Water at 26.25 feet and 6.42 feet above Mean Low Low Water at 32.81 feet.

Figure 8.34 Top: Ron May stands, C. Fred Buchanan stretches across the unit, Anne Peter sits at the upper right, and two unidentified crew members worked to the left at Field I in 1987. Bottom: Typical tile rubble at Field VIII. Fort Guijarros Museum Foundation Photo Collection, P:87-2632 and P:95-3163.

Figure 8.35 Jim Royle on the left shows Charlene Henning where to draw one of the tiles that he had just measured in the grid beneath him. They re-mapped Field I in 1987 so C. Fred Buchanan could apply his architectural code for later analysis and interpretation. Fort Guijarros Museum Foundation Photo Collection, P:87-2540.

Once the tile rubble had been mapped, the pieces were lifted, carefully examined, and stacked to one side (Figure 8.35). The cleaned cobblestone glacis received a second set of measurements. From the top of the contrafuera, a string had been pulled level at 10.8 feet above Mean Low Low Water. Plumb lines were then measured. At 5.41 feet along the line, the cobblestone glacis measured 10.24 feet above Mean Low Low Water. At 10.17 feet along the line, the cobblestone glacis measured 8.89 feet above Mean Low Low Water.

The above measurements and field observations provide a second set of data to substantiate the contrafuera consisted of the foundation core buttressed by a slope of cobblestones. The slope dropped 1.9 feet over a distance of 10.17 feet.
The secondary objective of the Field VIII investigation was to seek artifactual evidence in the merlones rubble to (a) determine the composition of the merlones battery face and (b) seek ceramic artifacts to date the demolition or collapse of the merlones. The 1981 and 1987 revisit to Field I recovered only one English white ware ceramic sherd of vague 19th-century vintage.

The Strata VIII soil in Field VIII was identical to the soil exposed in Field I. The following points are made from the Field VIII data:

1. Both contained melted and reconstituted unfired adobe block mixed with beach sand and mats of sea grass.

2. Two good samples of mud-mortared adobe block joints were recovered in 1995 to substantiate the role of adobe block in the construction of the merlones.

3. The low volume of unfired adobe block in the Strata VIII matrix substantiates the Field I observation that adobe framed but did not fill the merlones; sand filled the interior.

4. The presence of yellow-tan sand in relative abundance below the Strata VIII correlates to Stratum VI and VII in Field I, which could have filled the merlones and flowed down the glacis below the tile rubble.

Strata VIII at Field VIII confirmed the observation of Strata VIII at Field I that very few artifacts were deposited during the decomposition process of the wall. Detailed observation in Field VIII redefined the soil to be primarily water-melted adobe that flowed and settled among tile and mortar rubble from the merlones. The presence of white beach sand and sea grass are strong evidence that the merlones collapsed during a heavy flow of the San Diego River, during a high tide, and coincident with wave action that deposited both the sand and sea grass. The single Puebla Blue-on-white Majolica soup bowl sherd probably washed down with the collapsed merlón. The single English white ware bowl sherd, square nails, spike, and saw-cut food bone were probably deposited by civilian whalers long after Fort Guijarros collapsed.

One of the most dramatic discoveries at Field VIII was the layer or bed of hundreds of boulder-sized cobbles that lay inside the contrafuera and supported the cannon deck (Figure 8.36). Held behind the buttressed wall front, this feature prevented sliding on the layers of sand fill above and below. With help from the crew, C. Fred Buchanan mapped all the exposed cobbles in 1995.

Figure 8.36 View from the roof of Building 539, Navy Fire Station, looking southwest across Field VIII towards the tip of Point Loma. The field of excavation reveals a massive cobble layer set down by Spanish builders to support the Fort Guijarros wall superstructure. The grid square in the photograph was used for mapping. Photo by Mike Nabholz. Fort Guijarros Museum Foundation Photo Collection, P:89-280.

Conclusion

The 1981 to 1995 investigations by the Fort Guijarros Museum Foundation uncovered new information regarding the surviving remains of the 18th-century Spanish fort on Ballast Point. Although an enormous effort has gone into digging, architectural analysis, and reporting, a great deal more can be learned by further investigations.

The field blocks revealed the walls to be enormous in breadth and very complicated in construction. The various layers of mortared internal foundation walls were buttressed by layers of huge cobbles and clear beach sand that were held together by the plastered, fired clay tile façade, applied to an un-fired adobe shell to form the wall merlón.

The interior was filled with beach sand and the entire structure remained solid as long as no water penetrated the soft interior adobe. At some time in the mid-19th century, water did pierce the walls and several massive architectural landslides collapsed the merlones over the exterior sloping buttress (contrafuera or revestimento).

Behind the gun deck, the actual structure buttressing the massive walls remains unknown. Fields IV and VII yielded evidence of the kitchen, but more work is needed to define the range of daily activities at the fort.

Later whaling companies operated atop the ruined mound and the United States Army built an artillery battery in 1873 and filled in the beach with debris and sand. The site slipped into obscurity until the Navy and Fort Guijarros Museum Foundation joined forces in 1981 to investigate the surviving elements of the fort.

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Ballast Point. Journal of San Diego History 36(2):121-136. San Diego Historical Society, San Diego.
1985c The Guns of Point Loma: America’s First Sea Coast Artillery Defense in San Diego. The Military on Point Loma. Cabrillo Historical Association, San Diego.
1986 Dog Holes, Bomb-lances and Devil-fish: Boom Times for the San Diego Whaling Industry. Journal of San Diego History (36)2:73-90. San Diego Historical Society, San Diego.
1988 A Preliminary Report on the Summer-Fall 1988 Archaeological Field Season at Ballast Point, San Diego, California. Fort Guijarros Quarterly 2(3):4-25. Fort Guijarros Museum Foundation, San Diego.
1994 Field VIII Archaeology Report for The 1989-1993 Seasons. Manuscript on file, U.S. Department of the Navy, San Diego.
1995 Evidence for The Physical Appearance of 18th Century Spanish Cannon Batteries in California. Fort Guijarros Journal 1:4-15. Fort Guijarros Museum Foundation, San Diego.
1996 Research Design for the 1996 Investigation of the Interior Wall of a1796 Spanish Cannon Battery, American Army Artifacts, and the Ballast Point Whaling Station Located on the United States Naval Submarine Base, San Diego. Manuscript on file, U.S. Department of the Navy, San Diego.

Quillin, Col. Frank (ret.) and Margaret Quillin
1988 A Translation of Chapter VI of Don Pedro de Lucuze’s 1772 Principios de Fortificación as it Relates to the Design of the Fort at Punta de Guijarros, San Diego, California. Fort Guijarros Quarterly (2)1:3-7). Fort Guijarros Museum Foundation, San Diego.

Sandels, G.M. Waseurtz af
1945 A Sojourn in California by the King’s Orphan: The Travels and Sketches of G.M. Waseurtz af Sandels, A Swedish Gentleman Who Visited California in 1842-1843. Grabhorn Press, San Francisco.