See more from this Division: Topical Sessions
See more from this Session: Sediment in Fluvial Systems: Production, Transport, and Storage at the Watershed Scale II
Abstract:
Field mapping, survey, and OSL and radiocarbon geochronology undertaken indicate distinct reach characteristics linked to underlying bedrock. The upper drainage, encountering the Kayenta Formation, is characterized by bedrock knickpoints incising a valley dominated by gravelly Pleistocene strath terraces. In contrast, the middle reach that hosts the rock art is characterized by entrenched meanders in the Navajo Sandstone and a smoothly convex longitudinal profile. The upstream straths appear to converge towards the drainage in this reach and inflate into sandy fill terraces, whereas the overall stratigraphy is dominated by internally complex Holocene paleoflood deposits.
These patterns bespeak a fundamental change in sedimentation and storage as a function of reach geometry controlled by bedrock. There is more short-term storage and preservation in the alcoves and meander bends of the middle Navajo reach, whereas the upper Kayenta catchment records longer-term incision via episodic strath formation and knickpoint incision. Finally, the Barrier Canyon rock art physically must postdate T2 terrace formation and its subsequent incision, while predating rockfall activity at the type locality. These geochronologic constraints are being produced as this abstract is being written.
See more from this Division: Topical Sessions
See more from this Session: Sediment in Fluvial Systems: Production, Transport, and Storage at the Watershed Scale II