MANAGING CHANGE: THE ROLE OF DOCUMENTATION AND CONDITION SURVEY AT MESA VERDE NATIONAL PARK
FRANK G. MATERO
3 DIAGNOSIS: WHAT THE EVIDENCE SUGGESTS
The breakdown of conditions recording into discrete, symptomatic descriptions allows for the possibility of establishing correlations among conditions and across variables such as environment, composition, construction, and previous modern repairs. This accomplishment has been made all the more possible through the ability to better manipulate digitized data as discrete layered information systems with CAD and GIS software. Short of long-term monitoring, the careful recording and interpretation of existing conditions afford the conservator the opportunity to posit trends and potential cause-and-effect relationships. Instrumental monitoring provides the quantitative data necessary to understand the subtleties of change over time. However, what, where, how, and when monitoring occurs depend first on an understanding of the critical parameters affecting change through an initial reading of the existing physical evidence.
The overall recording of conditions in the context of supporting documentary information such as past uses, treatments, maintenance, etc. allows a working prognosis or prediction of causes, trends, patterns, and significance. These can later be supplemented and confirmed using other methods of investigation and analysis that lead to the point of diagnosis.
The following observations are a summary of the major conditions recorded for Kiva C, Mug House, during the field survey from 1995 to 1998. When considered in conjunction with other factors such as environment and microclimate, wall orientation and exposure, wall composition, construction technology, and previous interventions, these observations suggest a complex etiology for building and material performance and failure through time. The summary observations described below are intended to accompany and supplement the graphic data provided as printout and on screen and are organized by condition type (see fig. 6, page 60). In this way, multiple interpretations of conditions can be explored to reveal patterns and trends as well as anomalies related to time, location, and condition type. With the application of “smart” mapping programs such as ArcView, predictive modeling of conditions as indicators of future damage can offer expanded analysis and opportunities for better risk assessment for cultural resources at any scale.
Although definitive statements confirming the various mechanisms and rates of deterioration observed at Mug House, and specifically for Kiva C, must be deferred, at least until the environmental monitoring data have been finalized, several general correlative observations can be made on the basis of the visual survey and the architectural design and construction, and materials analysis and characterization of the mortars and surface finishes:
- Room/space location and orientation, in terms of exposure and grade, are significant factors in determining the overall condition of the stone, mortar, and architectural finishes of alcove sites, all other factors being equal. This relationship is due predominantly to the deleterious effects of water on the earthen materials either as direct precipitation (melting snow and rain) or as groundwater from percolation and rising damp through the sandstone (fig. 7, see page 60).
Plan of Mug House showing field-observed patterns of precipitation and active efflorescence. Courtesy Architectural Conservation Laboratory, University of Pennsylvania
- Room construction and use history appear to affect the early condition history of the finishes. Partial vitrification and embrittlement from intense burning both during and after occupancy, instability from the application of numerous plaster layers over time, use-related damage and the presence of carbon soot deposits between layers, as well as the ubiquitous loss of roofs after abandonment, have all affected the durability and hence condition of the finishes both before and after burial and excavation.
- Excavation and subsequent selective exposure to the elements, even in a protected environment such as the cliff alcoves, have caused the most significant damage to the fragile surface finishes. This damage is clearly evident in the increasing loss observed over time since excavation (after 1959 at Mug House).
A more detailed analysis of the observed conditions in Kiva C, discussed below by type (see appendix 1, pages 64–67), suggests various patterns and trends linked to the specifics of the above determinants.