227-10 Determining the Age of the Camas Prairie Ripples, NW Montana: A Combined Approach of Optically Stimulated Luminescence (OSL) and 10Be Cosmogenic Dating

Session: Recent Advances in Glacial Geology, Geomorphology, and Chronology (Posters)

Presenting Author:

Authors:

Abstract:

The Camas Prairie Ripples, located in NW Montana, are massive ripple-like dune and antidune features that are hypothesized to be the result of glacial outburst flooding from the impounded waters of Glacial Lake Missoula. However, there is still a question as to the age and number of flooding events that caused these features.

To understand the chronology of these flooding events, it is important to sample at key points where stratigraphic evidence indicates conditions reflecting multiple flooding events or ideal OSL bleaching conditions. It is also important to sample at depth stratigraphically at points farther from the ripple structure that represent waning flood stages. The three primary methods of analyses for these features will be: (1) small aliquot and single grain OSL analysis on landform matrix quartz and feldspar minerals; (2) OSL analysis on gravel-sized particles (rock-surface luminescence); and (3) ¹⁰Be cosmogenic nuclide dating on gravel-sized particles. While there are challenges to dating sediment from energetic, proximal, turbid deposits, there have been multiple successes in dating similar features using a combination of these previously mentioned techniques.

By determining the age and number of flooding events that caused these features, we will put these feature’s history in the context of the Quaternary history of Glacial Lake Missoula and the greater Channeled Scablands.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-11242

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