Documentation and Technical Study of Torqua Cave
This study represents original documentation, condition assessment and technical analysis of Torqua Cave, a significant rock art site on Santa Catalina Island located off the coast of Southern California. Documentation techniques include the use of Dstretch®, an image enhancement technique that assisted in the revelation of roughly 60 previously unrecognized images and markings, and the production of a three-dimensional model using Agisoft Photoscan, which has assisted in visualizing the shelter in ways previously impossible due to restrictions of the terrain. The local environment, including temperature and relative humidity of Torqua Cave was monitored for a total of five months and data were compared to a nearby weather station to assess potential correlations. Scientific analysis to investigate the state of conservation of the pictographs and rock support was performed using primarily non-invasive techniques such as portable X-ray fluorescence and fiber optic reflectance spectroscopy, which were complemented by X-ray diffraction analysis of a few microsamples. Gypsum and calcium oxalates could be identified as the primary contributors to the various weathering patterns. Based on the interests of stakeholders, recommendations are made for the preservation of the site including future monitoring and environmental survey.