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Grad student talk - Quaternary dating of hillslopes and terraces along the Colorado Front Range

Thursday, September 27, 2012, 4:30PM - 5:30PM


Melissa Foster


RL-1 room 269

Release of mobile regolith from underlying weathered rock (saprolite) is a crucial process in the evolution of landscapes. To calculate the lowering rate of the saprolite interface with cosmogenic radionuclides (CRN), it is often assumed that the mobile-regolith cover was steady over a timescale characterized by the saprolite-exhumation rate (ẇ) and decay length scale of CRN production. I collected in situ 10Be data along north- and south-facing transects in Gordon Gulch, within the Boulder Creek CZO, to test the steady-state condition on a complex hillslope. At steady state, the mean concentration of 10Be within a mobile-regolith column of thickness H may be calculated if the saprolite-exhumation rate is known independently. In situ 10Be data from saprolite samples may be used to document the saprolite-exhumation rate. Throughout this talk, I will explore whether our CRN data support the steady-state assumption. In addition to on-going work in the Boulder Creek CZO, I will also briefly discuss my new/future work on dating the deposition of Front Range terraces.