What does this nineteenth-century syringe excavated at El Presidio de Santa Bárbara State Historic Park have to do with an unassuming 1871 brick building at 914 -1916 Anacapa Street?
All will be revealed in the upcoming Winter 2016 issue of La Campana. Do you receive La Campana? This full-color publication is a benefit of membership in the Santa Barbara Trust for Historic Preservation. For more information on how you can keep up to date with wonderful articles on local history and the latest efforts at SBTHP, click here.
Meanwhile we’ll be putting the finishing touches on the story of a little known center of medical treatment in Santa Barbara, which will land in your mailbox soon!
In October 2015 the Santa Barbara Trust for Historic Preservation received a grant from the California Missions Foundation to investigate the architectural remains of the second outer defense wall. A small excavation unit was opened beneath the floor of the 1887 Bonilla house. The primary purpose of the investigation was to evaluate the condition of the wall. The exposure successfully identified in-situ adobe melt on the interior and exterior of the wall, identified the historic grade outside the wall, and recorded an episode of roof collapse on the interior of the wall. Lucas Nichols carefully exposed the wall including in-situ lime plaster on the interior surface.
Lucas Nichols excavating an exposure of the second outer defense wall beneath the 1887 Bonilla House shed. Photo by Mike Imwalle.
Intact section of second defense wall beneath the Bonilla House. Photo by Mike Imwalle.
All of the soil excavated consisted of adobe melt. Adobe melt is the soil that constituted the adobe blocks used to construct the wall. Over time, gravity and the weather cause the adobe to dissolve or melt and it is redistributed across the ground surface. Once the adobe melt has been archaeologically removed from the unit, artifacts, gravel, and other debris are removed from the soil with 1/8″ sieves. The sterile sandy loam that falls through the screen is recycled into new adobe bricks for reconstruction. Today the soil Lucas is screening is going right back into the walls as mortar. The walls are being rebuilt using soil recycled from the melted bricks originally laid on the second defense wall in the late 1790s.
Sifting excavated soil through 1/8″ screens. Photo by Mike Imwalle.
Isidro Ruiz adding screened soil to the mixer to make mortar. Photo by Mike Imwalle.
This week we began the last phase of the Presidio Northwest Corner project. Trust Board member Tim Aguilar and Restoration Specialist Isidro Ruiz are laying adobe blocks to complete the three corral or yard walls behind the recently constructed adobes at the Northwest Corner. These backyard areas will provide outdoor exhibit space for the new Presidio Visitor Center. Watch the progress as the last walls of the Northwest Corner project are completed!
Tim Aguilar spreading mud mortar on the sandstone foundation. Photo by Mike Imwalle.
Tim Aguilar laying first course of adobe blocks on sandstone foundation. Photo by Mike Imwalle.
Mike Imwalle is the archaeologist at the Santa Barbara Trust for Historic Preservation
In November 2012 author and illustrator David Rickman paid a visit to El Presidio SHP. David paints amazingly evocative images of early California, with an emphasis on the dress and equipment of eighteenth- and nineteenth-century residents. His paintings are based on meticulous research into both the historic record and historical collections. He has worked frequently for the National Park Service and for California State Parks. In fact, if you have been to a state or national park interpreting early California history, you have likely seen David’s work.
David’s recent visit was part of the research phase for a new project for California State Parks: a costume guide and manual for California’s Mexican and early American periods which will be used as a tool system-wide through State Parks. David visited collections throughout southern California on this trip, and documented objects at many of them. At El Presidio SHP, David was most interested in archaeological material uncovered in the Presidio site, of which many highlights are on display in the Documenting Everyday Life exhibit on the Presidio’s Northeast Corner. Staff Archaeologist Michael Imwalle assisted David with pieces he was interested in, including lance points and spurs, which he photographed for his records.
Although we hope that State Parks or another agency will commission a future publication focusing on California’s Spanish colonial period, which includes the primary interpretive period for El Presidio SHP, the Santa Barbara Trust for Historic Preservation will benefit enormously from David’s forthcoming work. We are committed to interpreting all the layers of history of the Presidio neighborhood, and David’s research will enhance the accuracy of our presentation of material culture.
Anne Petersen is Associate Director for Historical Resources at the Santa Barbara Trust for Historic Preservation.
The previousinstallments of this series briefly described the process of extracting or mining clay and the fabrication of roof and floor tiles. This post will describe methods employed for firing roof and floor tiles. Once the molded tiles have been air-dried they are ready to be fired. The drying process is a critical step in tile production. If tiles are not completely dried before firing, moisture trapped in the clay expands as it is heated during firing and the tiles explode. Because the various steps in tile production are so labor intensive it is important to maximize the amount of tiles that are successfully fired. Drying and firing are slow processes that require patience. Trying to speed up either of these to activities will result in the loss of large amounts of tile during firing.
The first step in the firing process is the loading or stacking of the kiln. The unfired or “green” tiles are carefully stacked inside of kilns for firing. The unfired tiles are extremely brittle and great care needs to be taken to stack the tile without breaking them. Roof tiles, or tejas, are typically stacked in rows on end. Floor tiles, or ladrillos, are carefully stacked on their sides with space between them for the hot air and gasses of the kiln to circulate. Leaving air space around the tiles is critical to achieving and maintaining a constant temperature during firing. Without good circulation of air around the tiles hot spots and cold spots can develop within the kiln creating a firing environment that leads to correspondingly over-fired and under-fired tiles.
Although we do not know exactly what type of kilns were used to fire the tiles at the Santa Barbara Presidio, we do have contemporary examples from the period. A sketch of the Monterey Presidio tile kilns depicts circular tile kilns built into the hillside adjacent to the fort. A similar tile kiln has been restored a Mission San Luis Rey de Francia. This type of kiln would have had two chambers. The lower, or firing, chamber was accessed by an arched opening at the bottom of the kiln. This is where the stoker, or quemador, would diligently tend the fire to maintain a constant temperature of around 1800⁰ for up to twenty-four hours.
The upper chamber of an updraft kiln is for the wares, or in this case tiles. They would have been loaded from the top and stacked to fill the upper chamber. The upper chamber is supported by a grate formed by a series of tile arches. Once the upper chamber was loaded with tile the top was covered with adobes or tiles to prevent the hot gasses in the kiln from escaping through the top. Because of the intensity of the fires and duration of the firing process, tremendous amounts of wood or other fuel was necessary to keep the kilns stoked.
Another example of circular tile kilns in Santa Barbara County is the tile kiln documented by Frs. Lynch and O’Brien at the Santa Barbara Mission. Archaeologically, Harrison identified the base of a circular tile kiln at La Purísima Mission in 1940.
A similar kiln was used to fire tiles for the Rancho San Marcos Adobe in circa 1804. While an open-topped square kiln has been identified at San Antonio Mission, documentary and archaeological evidence suggest that the circular kilns were predominant.
Where were the Santa Barbara Presidio kilns? Part one of this series suggested that the clay source for presidio tile was likely located on a slope northeast of the Presidio. Part two of this series documented the fact that the kilns would likely have been located near the clay source. This would place the kilns somewhere near the clay source northeast of the Presidio quadrangle.
While no archaeological evidence of the kilns themselves have been identified in this portion of the site, artifacts recovered during construction monitoring of a nearby development did identify wasted tiles. Three tiles were actually melted together from over-firing. Although this does not definitively identify the location of the Presidio tile kilns, the wasted tiles are evidence of tile firing somewhere in the neighborhood. Stay tuned as we continue our research!
Michael Imwalle is the archaeologist at the Santa Barbara Trust for Historic Preservation.
The previous installment of this series briefly described the process of extracting, or mining, clay and processing it to prepare for the fabrication of roof and floor tiles. This post will briefly describe methods employed for molding, forming, and drying tiles prior to firing. In contrast to clay for making pottery, which must be kept moist and pliable during pottery production, clay for tiles needs to be relatively stiff and free of excess moisture. Clay used for the fabrication of roof tiles, or tejas, for example, needs to be moist enough to push into trapezoidal-shaped templates, but stiff enough to remove from the templates and place onto semi-cylindrical, tapered molds. Once the desired barrel shape is realized on the mold, the wet tile was removed to dry on the ground or on racks. Like the roof tiles, floor tiles, or ladrillos, were formed by pushing relatively stiff clay into square or rectangular molds then removing the tiles to air-dry before firing.
Tiles were probably made relatively close to where the clay was mined and where the tiles were ultimately fired in kilns. Kilns are typically located close to the clay source (see previous post for possible clay source location) and downwind from residences to avoid the risk of fire and excessive smoke and ash. Kilns are also located relatively close to construction sites so as to cut the cost of transportation and reduce the amount of breakage during delivery. We know from archaeological and historical evidence that ladrillos were fired for the presidio aqueduct by 1784. By 1786, thousands of tejas had been installed on the first wing of the adobe quadrangle and thousands more were ready for firing.
During the presidio era, templates, or forms, for roof tiles would have been constructed of hand-planed lumber fashioned to the desired thickness of the tile. Molds for the tiles could be fashioned in a number of ways, including forms carved from a single piece of wood and forms assembled from semicircular pieces of wood attached with wooden slats. Legend has it that roof tiles were formed on the thighs of “Indian women.” Although forms could be fashioned from a variety of materials, according to archaeological evidence, thighs do not appear to have been one of them!
During an attempt to replicate tile manufacturing and firing processes for the Smithsonian-sponsored “Ceramics Rediscovered” exhibit, SBTHP archaeologists used plaster of Paris to make a mold of an original presidio roof tile to insure accuracy in the replication process. Each 24-inch-long roof tile that tapers in width from 12 inches to 8 inches takes approximately 25-30 pounds of wet clay. Due to the fact that the wet clay shrinks about 10-12 percent when it dries, the molds need to be made slightly larger than the desired finished dimension of the tiles. Once the tiles have been dried and fired their weight is reduced to approximately 18 pounds each.
It took more than 75,000 tejas to roof the buildings and outbuildings of the original Presidio quadrangle. That required 2,250,000 pounds (1125 tons) of raw clay to be extracted and processed to make the tiles. To find out how and where all those tiles were fired, stay tuned for Part 3.
Michael Imwalle is the archaeologist at the Santa Barbara Trust for Historic Preservation.
Fired clay tiles were introduced as a building material at the Santa Barbara Presidio early in its development. Floor tiles, or ladrillos, were fired at the presidio for the construction of the presidio aqueduct by 1784. By 1786 enough roof tiles, or tejas, had been made to cover the buildings of the first wing of the presidio quadrangle. This is the introduction to a three-part series on tile production at the Santa Barbara Presidio. Part one will summarize the mining and processing of raw clay, part two will outline the tile fabrication process, and part three will examine the firing process.
The site of the Santa Barbara Presidio was chosen for strategic purposes, but also for its proximity to valuable resources for construction. The site was covered with sandy loam topsoil ideal for making sun-dried adobe bricks. A thick layer of well-developed yellowish brown, sandy clay lies just beneath the topsoil used for making the adobes. The only way to get to the underlying clay layer is to remove the entire layer of topsoil or to dig into the clay layer from the side.
The area where presidio soldiers and Chumash laborers mined clay for the presidio tiles was likely due north of the quadrangle on a north-facing slope above the slough or estero. During the reconstruction of the new Northwest Corner Visitor’s Center in 2007, clay was excavated from the bottom of the foundation trenches using a backhoe. Mineralogically it is identical to the clay mined for Presidio roof and floor tiles more than 225 years ago.
For the past six years, we have been using experimental archaeology to replicate historical fabrication and firing techniques for tile and pottery. Archaeological interns from The Anacapa School assisted with the processing of the clay. First, the raw clay is soaked in barrels of water for several weeks to liquefy the material for screening. Next, the clay is pushed through screens to remove roots, rocks, and other impurities. Once the clay has been screened, it’s time to remove some of the excess moisture. The liquefied clay slurry is poured into cloth bags to assist with the evaporation of water from the clay. Once enough water has been evaporated for the clay to be stiff enough to mold, it is bagged in plastic for storage and transported to the pottery shop for fabrication into tiles and other vessels.
The next installment of this post will examine the actual fabrication process, then, finally, a summary of the various firing techniques likely used for producing tile at the Presidio.
Mike Imwalle is the archaeologist at the Santa Barbara Trust for Historic Preservation.
by Michael Imwalle, Robert Hoover, and Anne Petersen
In 1994, a small religious medal was recovered from the Northwest Corner of the Santa Barbara Presidio quadrangle during the Cal Poly San Luis Obispo Archaeological Field School. Dr. Robert Hoover directed the excavation, which was intended to identify the location of the bastion on the Presidio’s northwest corner. While the excavation did not result in identifying the former bastion location, it was successful in identifying a suite of two adobe rooms that were added to the north end of the west wing of the presidio quadrangle some time before 1795. Given the archaeological context of the find, and what appeared to be an inscription in Spanish, we initially assumed that the medal was probably deposited during the Spanish or Mexican period occupation of the Presidio.
After a preliminary cleaning of the medal, it was identified as a religious medal bearing the name and likeness of Santa Vibiana. Saint Vibiana was a third century Christian martyr buried in catacombs in San Sisto on the outskirts of Rome near the Appian Way. Her burial vault was rediscovered during excavations of the site which were authorized by Pope Pius IX in 1853. The unopened sepulcher was sealed with a marble tablet bearing the Latin inscription “To the soul of the innocent and pure Vibiana, laid away on the day before the kalends of September [August 31].” A laurel emblem commonly used for early Christian martyrs was found at the end of the inscription. After several weeks, an investigation led to the canonization of Vibiana. Clearly the medal bearing the name “Santa Vibiana” postdated her canonization.
What does Pope Pius IX, the Appian Way, and a third century Christian martyr have to do with the Santa Barbara Presidio? That question was answered by the late art historian Dr. Norman Neuerburg when he revealed that the remains of St. Vibiana were once housed in the Presidio Chapel. As it turns out, Bishop Thaddeus Amat was entrusted in 1854 with the bones of Vibiana, the marble slab, and a vial of blood from the tomb as relics for the Old Plaza Church in Los Angeles. Amat sailed from LeHavre, France, to New York, to Panama, and finally to San Francisco. Travelling on the coastal schooner, Powhatten, Amat’s journey to Los Angeles was interrupted by a sudden storm, forcing the ship into Santa Barbara harbor on December 2, 1854. The relics were temporarily placed in a special reliquary with a golden crown to the right of the Presidio Chapel altar. Later they were moved to Our Lady of Sorrows parish church where they resided until it was destroyed by fire in 1863. Miraculously, the relics survived the fire and were eventually moved to the old Parish Church in Los Angeles in 1868.
A recent inquiry by UCLA graduate researcher Vitaly Efimenkov led to the re-inspection of the inscription of the medal excavated at the Presidio in 1994. The medal was soaked in a bath of mild detergent in an ultra-sonic cleaner and gently cleaned with wooden picks, dental picks, and tooth brushes. After repeating the process for several days we were able to decipher considerably more of the inscription. Roughly translated the inscription on the front reads, “Saint Vibiana, Virgin and Martyr.” And the back, “Oh Mary, conceived without sin, pray for us, we need your protection.” Amazingly, even some of the original gold plating began to re-emerge. Thank you, Vitaly, for instigating this process. I hope that your research sheds some light on why St. Vibiana’s remains ended up staying in Santa Barbara for almost fourteen years on the way to Los Angeles. Who could blame her, Santa Barbara is a special place!
Mike Imwalle is the archaeologist at SBTHP. Robert Hoover is Professor Emeritus of Archaeology at Cal Poly San Luis Obispo and president of the board of SBTHP. Anne Petersen is Associate Director for Historical Resources at SBTHP.
SBTHP recently welcomed Dr. Lewis Somers of Geoscan Inc. to El Presidio de Santa Barbara State Historic Park to give a lecture and hands-on demonstration of geophysical survey techniques. The lecture was part of SBTHP’s Archaeology Month programming. On Saturday, October 15th, 2011 Dr. Somers discussed the use of various geophysical survey methods including ground penetrating radar, resistance, and magnetics. He also discussed the effectiveness of the various techniques at other Spanish Colonial period sites.
Following the lecture some of the attendees adjourned to the yard behind the comandancia for a hands-on demonstration of magnetometer survey and magnetic resistance survey. Both techniques employ the use of a grid system to collect data at predetermined spots across the site. Ropes representing the grid points are stretched across the site at one meter intervals. Correspondingly, each rope is marked with tape every meter. By walking along the ropes and timing the cadence of the instrument to record data at every meter marked on the rope, the data collected represents a grid of one meter squares across the site. While the magnetometer is carried just above the ground to collect data about the magnetic qualities of what is beneath the surface, the resistance meter consists of two probes inserted into the ground to measure electronic current as it passes through objects beneath the surface.
The purpose for Dr. Somer’s visit to California was twofold. After the lecture at the Presidio, Dr. Somers packed up his equipment and hauled it over the pass to the Santa Inés Mission. He was contracted to survey the adobe apartments for neophytes formerly located south of the mission quadrangle. The survey was funded by the California Missions Foundation. On October 17th, 2011, SBTHP volunteers and staff assisted with establishing a one meter by one meter grid across an area measuring almost 200 meters by 200 meters. SBTHP Board President Bob Hoover, Santa Inés Mission Mills Steward Wayne Sherman, and volunteers Allison Lorber, Lucas Nichols, Arturo Ruelas and I assisted with moving the survey ropes across the site as Dr. Somers recorded the magnetic data.
Different techniques can provide varied results depending on a number of factors including the type of soil, the amount of iron in the soil, the amount of moisture in the soil, and the underlying geologic formation. Other factors such as the amount of “electronic noise” from metal fencing, underground, conduits, and overhead communications and power lines can also affect results. The best technique is the technique that provides the best results. The results may be partially determined by factors that can change like the amount of moisture in the soil. Because the soil was very dry in October, Dr. Somers concluded that it was not practical to use resistance. He will return to the site in April 2012 to re-survey the same areas using resistance after the rainy season and be able to compare the results of the two techniques.
Geophysical survey is an extremely valuable tool for archaeologists for developing research designs, testing strategies, and resource management. Having an idea about what is under the ground before an excavation allows limited resources to be focused on areas where there is a high probability of encountering features. Knowing where buried features lay without having to excavate them allows interpretation of the site without damaging it. It also provides information to archaeologists and planners to help avoid archeological resources during development projects and preserve them in situ for future generations of researchers.
Mike Imwalle is the archaeologist at the Santa Barbara Trust for Historic Preservation.
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