The role of lithology and climate on bedrock river incision and terrace development along the Buffalo National River, Arkansas

The Buffalo National River in northwest Arkansas preserves an extensive Quaternary record of fluvial bedrock incision and aggradation across lithologies of variable resistance. In this work, we apply optically stimulated luminescence (OSL) dating to strath and fill terraces along the Buffalo River t...

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Bibliographic Details
Published inQuaternary research Vol. 115; pp. 179 - 193
Main Authors Rodrigues, Kathleen, Keen-Zebert, Amanda, Shepherd, Stephanie, Hudson, Mark R., Bitting, Charles J., Johnson, Bradley G., Langston, Abigail
Format Journal Article
LanguageEnglish
Published New York, USA Cambridge University Press 01.09.2023
Subjects
Aggradation
Geology
Lithology
Quaternary
Research Article
Rivers
Sea level
Sediments
Soil erosion
Stone
Surface water
Terraces
Valleys
Watersheds
United States > US
Arkansas
Buffalo River
Paleoclimate
Geochronology
Geomorphology
Bedrock rivers
Strath terraces
OSL dating
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Summary:The Buffalo National River in northwest Arkansas preserves an extensive Quaternary record of fluvial bedrock incision and aggradation across lithologies of variable resistance. In this work, we apply optically stimulated luminescence (OSL) dating to strath and fill terraces along the Buffalo River to elucidate the role of lithology and climate on the development of the two youngest terrace units (Qtm and Qty). Our OSL ages suggest a minimum strath planation age of ca. 250 ka for the Qtm terraces followed by a ca. 200 ka record of aggradation. Qtm incision likely occurred near the last glacial maximum (LGM), prior to the onset of Qty fill terrace aggradation ca. 14 ka. Our terrace ages are broadly consistent with other regional terrace records, and comparison with available paleoclimatic archives suggests that terrace aggradation and incision occurred during drier and wetter hydrological conditions, respectively. Vertical bedrock incision rates were also calculated using OSL-derived estimates of Qtm strath planation and displayed statistically significant spatial variability with bedrock lithology, ranging from ~35 mm/ka in the higher resistance reaches and ~16 mm/ka in the lower resistance reaches. In combination with observations of valley width and terrace distribution, these results suggest that vertical processes outpace lateral ones in lithologic reaches with higher resistance.
ISSN:0033-5894
1096-0287
DOI:10.1017/qua.2023.16