Paper No. 4
Presentation Time: 9:45 AM
RELATING THE HOLOCENE ALLUVIAL RECORD OF KANAB CREEK TO NEARBY FLUVIAL AND EOLIAN RECORDS IN SOUTHERN UTAH
In the semi-arid desert of southern Utah, vertically-walled entrenched stream channels termed arroyos are abundant on the landscape. Chronostratigraphic reconstructions suggest that these systems were characterized by millennial-scale periods of aggradation episodically interrupted by decadal-scale arroyo-cutting events during the middle to late Holocene. Our research has focused on the arroyo and terrace exposures along Kanab Creek near Kanab, Utah, and has identified at least four periods of fluvial aggradation since the middle Holocene: 6.5-3.6ka (Qa4), 3.2-2.6ka (Qa3’), 2.0-1.2ka (Qa3), 0.8-0.2ka (Qa2). Each period of aggradation was on the order of 20-40 m and was separated by rapid entrenchment of the same scale, producing complex inset stratigraphic relationships that are not related to geomorphic terrace height.
Arroyo entrenchment has been primarily linked to hydrologic variability, although the specific climatic conditions related to and preceding incision events are still debated. Previous research has suggested synchronicity of valley incision and aggradation across the region due to hydro-climatic changes. We compare the Kanab Creek record with emerging chronologies from nearby drainages to test this hypothesis. We also utilize local eolian records from the Coral Pink Sand Dunes and Kanab Dune Field to explore the associations between the timing of alluvial aggradation and incision in Kanab Creek and eolian activity.