What are slackwater sediments?
Slackwater sediments are deposited at the mouths of tributaries due to inundation by water along the mainstem river. These fine-grained deposits preserve sediments carried down the mainstem river.
In this project, I am working with UMN Undergraduate Abigail Wilwerding, to understand the source of glacially-derived slackwater sediments collected near the mouth of our field area in southeastern Minnesota. We are using a combination of core description, optically stimulated luminescence (OSL) and X-ray fluorescence (XRF) to identify these sediments and relate their deposition to past glacial meltwater routing down the Mississippi River. This project aids our understanding glacial sedimentation and sediment sourcing of the Mississippi River during the most recent glacial period.
Glacially Modulated Base Level Change Impacts on River Channel Long Profile
As the Laurentide Ice Sheet retreated after the Last Glacial Maximum, pulses of glacial sediment and meltwater dramatically altered base level for tributaries connected to the then proglacial Mississippi River. By pairing glacial chronology with river channel long profile evolution and bedrock morphology during this period, we are able to build a field-based dataset that demonstrates how rivers respond to changing base level without additional tectonic signals. This, in turn, allows us to test models of how transport-limited river systems respond to perturbations using real world, physically-based data.
Left: Fieldwork in the Aklavik Range, NWT, Canada; Right: Augering river terraces in Southeastern Minnesota, USA
Left: Fieldwork in the Aklavik Range, NWT, Canada; Right: Augering river terraces in Southeastern Minnesota, USA
Left: Fieldwork in the Aklavik Range, NWT, Canada; Right: Augering river terraces in Southeastern Minnesota, USA
Left: Fieldwork in the Aklavik Range, NWT, Canada; Right: Augering river terraces in Southeastern Minnesota, USA
Left: Fieldwork in the Aklavik Range, NWT, Canada; Middle: Luminescence dating at Utah State University, USA; Right: Augering river terraces in Southeastern Minnesota, USA