Abstract

Understanding the evolution of Lake Agassiz is vital to developing a comprehensive late Quaternary history of central North America. Although many of the geomorphic features of the lake are well known, current reconstructions primarily depend upon relative ages of landforms. Here, we report new optically stimulated luminescence (OSL) ages on a flight of strandlines located ∼140 km north of the southern outlet. Strandline ages at this location range from 14.3 ± 0.2 to 10.0 ± 0.2 ka cal, spanning ∼4000 years of lake history. Using geomorphic relationships and OSL age control, it is proposed that the Herman through Tintah strandlines developed over a period of <1000 years followed by a hiatus of strandline development until the Campbell strandline developed at 10.3 ± 0.2 ka cal. There is agreement between our new OSL dates and OSL and radiocarbon ages from geomorphically correlative landforms elsewhere in the lake basin. The use of high-resolution LiDAR imagery greatly aids localized mapping of shoreline features. Additional site-specific field work and OSL ages are necessary to further evaluate strandline tracing across the basin.

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