Students mapped 237km of the Missouri River valley between 2008-2010 to compare patterns of change between the upper and lower reaches. Optically stimulated luminescence dating found that the transition from meandering to braided river patterns occurred rapidly around 1.5 thousand years ago upstream, but was more gradual downstream from 3.5-1.5 thousand years ago. This suggests the upstream effect of climate change on river patterns migrated downriver over time in a counterintuitive pattern.

1. Coupling Rates from OSL for Pattern Changes Triggered by Climate Change in the Trunk Missouri River Belt
During the Holocene: A Counter-Intuitive Up-Dip Migration in Response
Abstract:
NSF/REU and USGS EDMAP
students working through University of
Texas at Arlington and University of
Nebraska at Lincoln mapped the
Missouri River Valley floodplain from
Yankton, SD to Missouri City, IA
(237km) between 2008-2010.
Mapping was intended to compare a
previously mapped 100km reach
500km downdip in Missouri to
determine coupling rates for pattern
changes in the river during the
Holocene. Particularly, the project
aimed to asses if changes from a
largely meandering loop system to a
heavily braided system observed
downdip could be indentified updip,
and if so, could comparisons be made
between timing and rate of change
between updip and downdip parts of
the trunk system?
Methods:
Students participating in the field
research applied consistent techniques
whereby a team of two is assigned a
quadrangle and mapping is carried out by
hand augering to test consistently between
lithofacies association and landforms
hypothesized from air photos at multiple
sites. Data are collected and interpreted
by each team individually and recorded in
GIS format. Transitions in loop style
indicative of changing river patterns were
assessed by dating of discrete loop forms
near transitions using optically stimulated
luminescence (OSL) testing.
Author(s): Adam Trimble, Justin Anderson, Chris Hendrix, Rachel Albertson, Diana Flores, David Grasman, Jenna Newman, Vince Egyed, John Patten, Shane Patterson, Michele
Kashouh, Dan Carlin & Dr John Holbrook. AKA The Mud Rangers
Conclusion:
Transition from meandering to braided is
rapid updip, occurring at approximately
1.5k.b.p. The transition is more diffuse
downdip beginning at 3.5k.b.p. and completing
at approximately 1.5k.b.p. The change is basin-
wide and presumed to record climate change
within the up-dip drainage. Counter to
conventional belief, this upstream effect
appears to have manifest down-dip first, then
complexly migrated up dip.
Acknowledgments/References:
The 2010 Mud Rangers would like to thank The University of Texas at
Arlington’s Dr John Holbrook, The University of Nebraska at Lincoln’s Dr Ron
Goble; The National Science Foundation and the USGS as well as the Lewis
and Clark Anthropology Group and Google Maps for materials used. We
would also like to thank every group of Mud Rangers that paved the way down
the Missouri River in previous years.
Drill Analyze Collaborate
2010 Mud Ranger Mapping Area
Missouri River Basin
0.67ka
1.78ka
1.01ka
6.59ka
7.29ka
6.59ka
0.68ka
1.56ka
4.68ka
Transitional Morphology 4a
3.4+/-.1kbp – 1.3+/-.1kbp
Meandering Morphology 3
4.4kbp+ - 3.4+/-.1kbp
Braided Morphology 4a -4b
3.0 – 1.2 +/-.1kbp
Transition
Braided
Morphology
Meandering
Morphology
Meandering
Morphology
Braided
Morphology
3.49ka
0.46ka
11.2ka
14ka
1.53ka
0.95ka
10.2ka
16.8ka
0.95ka
OSL Dates from Point-bars of Meander Loops
Morphology 1
Morphology 2
Morphology 3
Morphology 4bMorphology 4a
0.59ka