SALINAS "In the Midst of a Loneliness": The Architectural History of the Salinas Missions

NATIONAL PARK SERVICE STABILIZATION, 1980-1987

The 1982 Season at Abó

Salinas National Monument was created on December 19, 1980, but the National Park Service did not assume management of the sites of Abó and Quarai until October 2, 1981. Stabilization crews could not begin work at Abó until May, 1982.

The 1982 work was the first phase of a four-year stabilization project designed to pull the ruins into a safe, easily maintained condition for the first time since 1975. The first year was to cap walls and correct problems that could result in severe collapse or threaten visitor safety, with the goal of allowing visitation of the ruins beginning in 1983. The subsequent years would address lower priorities, but would find stabilization solutions to long standing problems of wall collapse and decay. One such solution was the installation of a drainage system to stop the pooling of water in some areas of the church and convento. The pooling was contributing to the decay of mortars and the sandstone itself in the lowest courses of masonry. [6]

Although Abó had not been stabilized since the work in July and August, 1972, a period of almost ten years, most of the damage that had occurred in the interval was mortar erosion and some loosening of stone in areas untreated since 1938-39. No major cracking or wall shifting had become apparent since the desperate measures undertaken on the "tower" in 1973. Apparently the repairs carried out by Kayser and Caperton had succeeded in stopping the separation of the various buttresses of the corner. The "Assessment of Effect" (XXX form) for the stabilization of Abó specified that the mortar would be a mixture of earth fill, natural clay, and calcium aluminate cement, mixed in the ratio of one part calcium aluminate, two parts screened earth, and two parts screened clay, with the earth and clay components selected so that the final dry color would match that of the original clay mortars used in the construction of the building. In the field, the stabilization crew experimented with various mixes and found that the calcium aluminate made the mortars too grey or pale for the proposed mixing ratio to be useable. Finally, a good color match was achieved with a mixture of fourteen parts screened earth, one part sand, and one part calcium aluminate. This made a weaker mortar than intended, but still stronger than the natural clay mortars used in the original construction. [7]

Stabilization in 1983

The stabilization crew changed the mortar mix for work in 1983. The mixture of fourteen parts earth to one part calcium aluminate used in 1982 was found to erode too easily, and a stronger mixture of seven parts earth to two parts calcium aluminate (a ratio of 3.5:1, close to the mixture proposed in the 1982 "assessment of effect") was tried in 1983. Again, the earth component was carefully selected so as to closely approximate the color of the original mortar. [8]

Stabilization in 1984

In March, 1984, the National Park Service carried out an intensive inspection of the ruins of Abó. With the completion of the initial stabilization the previous year, the Park Service could begin planning for long-term maintenance of the ruins. The 1984 inspection had as its primary goal the identification of probable future trouble-spots. One clear indication was that basal erosion of both mortar and the stones themselves was a continuing problem. The method of construction used by the Franciscans was a principal cause of this problem. Because they levelled the site by constructing an earthen platform with vertical stone retaining walls, they created a situation where earth fill was higher on one side of many of the wall bases. After the loss of the roofing over the platform and the later excavation of the ruins, the earth fill began to hold water and allow it to percolate through the retaining wall. This has caused the faces of the retaining walls to remain damp far longer than the higher masonry, encouraging mortar and stone decay. As a result, the wall faces along these areas of higher interior soil have tended to deteriorate more quickly and collapse sooner than the walls with no fill on one side. [9]