Date of Graduation

5-2014

Document Type

Thesis

Degree Name

Master of Arts in Geography (MA)

Degree Level

Graduate

Department

Geosciences

Advisor/Mentor

Paradise, Thomas R.

Committee Member

Dixon, John C.

Second Committee Member

Sabo, George III

Keywords

Petra; Rock decay; Sandstone; Tafoni; Thresholds

Abstract

Petra, Jordan captivates tourists and researchers with its dramatic sandstone cliffs, Nabatean, Roman, Byzantine and Roman architecture, and rich cultural heritage. However, increasing tourism in the valley is exacerbating stone degradation and complicating heritage management. This research analyzed environmental influences on dressed stone decay via tafoni development and evaluating cell evolution on an isolated hewn feature, known as Djinn Block X. Resembling other sandstone blocks found in the area, this irregular sandstone monument exhibits faces ranging in size from 2.5m by 3.5m to 3.9m to 4.2m (29m perimeter). Protruding features, incisions along the top, and a large platform attached to the northern face suggests this monument was ritualistic or unfinished.

Over twenty morphometric and micrometeorologic variables were measured for the ten largest and smallest tafoni cells per face. Data were examined and analyzed statistically, photographically, and cartographically. A mirrored-value-aspect matrix was created to reveal statistical relationships between aspect and detailed measurements including cell depth, average diameter, estimated volume, surface temperatures, ambient temperature, and humidity. Results supported field observations displaying greatest decay on the southern and northern faces with r2 values as high as 0.157 at 144˚N for cell volume (total material lost). Moreover, morphometric data exhibited episodic spikes in cell growth, both by depth and diameter, supporting a possible threshold response explanation. These findings challenge steady-rate decay models and represent major implications for rock decay and tafoni research, as well as cultural stone assessment. Furthermore, Geomorphologic research such as this provides policy-makers information necessary to improve conservation efficacy for crucially sensitive heritage sites.

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