THE EVOLUTION OF ROCK DOME EXFOLIATION THROUGH TIME AND SPACE: COMPARISONS BETWEEN CLIMATIC, GEOMORPHIC, AND GEOLOGIC SETTINGS

Exfoliation domes and their associated surface-parallel sheeting joints have been a perplexing geologic feature for over a century, despite their abundant presence worldwide and significant influence on numerous Earth processes, such as hydrology, mass-wasting, and regolith/soil production. Competing hypotheses exist regarding the formation of sheeting joints and exfoliation. However, as recently reviewed by Martel (2017), any singular existing hypothesis is insufficient in explaining the complicated, differential scales of sheeting joint formation. Multiple recommendations are made in his review to improve the understanding of sheeting joints; for example, mapping fresh sheeting joints where the depth of the joints can be quantified. These data would be valuable in modelling sheeting joint formation, but have not been systematically collected , particularly across different sites. The purpose of this study is to further understand these ambiguous features by assembling a unique data set addressing the morphology and mechanical weathering characteristics of sheeting joints. These data were collected and analyzed on 7 granitic exfoliation domes in four different geologic, geomorphic, and climatic settings, including sites near the Sierra Nevada range in California and the Blue Ridge Mountains in North and South Carolina. Preliminary results from observed chronofunctions of weathering features provide evidence of a recurrence interval of slab formations that may be continuous through time and space, and with predictable variance in morphology, despite their different geomorphic settings and presumed exhumation history. This comprehensive data set and preliminary analysis can further be used to test existing hypotheses of sheeting joint and exfoliation slab formation mechanisms.