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Aitkin County Glacial Geology Overview and How it Relates to Water��Carrie E Jennings��

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Aitkin Sand and Gravel Map

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MGS Publication M-164

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https://pubs.usgs.gov/sir/2020/5039/sir20205039.pdf

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Geologic History Section

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History of overlapping ice advances needs to be understood.

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Ice lobes that impacted the region

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Geologic History Section – Cross Section

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What forms at the edge of an ice sheet or ice lobe?

  • Moraine
  • Meltwater stream
  • Fan
  • Lake
  • Debris flows
  • Glacial thrust block
  • Ice stagnation deposits
  • Maybe nothing

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A hill and a tunnel

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Interested in the effect of the topography of the Mesabi Range on ice flow

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South End, Rouchleau

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Canisteo Pit at Bovey

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Thrusting of rock

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http://www.swisseduc.ch/glaciers/

St. Louis sublobe was the most recent advance

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Things covering Rainy lobe deposits

  • Peat
  • Water
  • Wind-blown sand and loess
  • Lake sediment
  • Glacial sediment

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Interlobate area, less cover?

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Interlobate area, Ball Bluff

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Ice Walled Lake Plain

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Collapsed stream sediment

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Debris flows of till

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Debris flows, glacier foreground, Matanuska

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Tamarack and Savanna Portage State Park are in the interlobate area

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Lake Sediment Cover

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Glacial lake Aitkin-Upham

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Later drying of the lake created dunes

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Dunes now buried in peat

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Glacial Landforms �with �sand and gravel

    • Glacial stream sediment - pink
    • Modern stream sediment- yellow
    • Dunes and wind-blown sand- peach
    • Collapsed stream sediment – orange
    • Deltas or shallow lake

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These landforms are highlands in interlobate area

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Mix of highlands and channel formed in west

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School Trust Land near Quadna Mountain, NW Aitkin Co.

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These are important groundwater recharge areas

  • There may be other areas in the blue (lake plain) where groundwater is recharged because the lake-sediment texture varies.

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  • Superior lobe tills can be sandy and tills in general are not perfect barriers to groundwater flow.

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Glacial Landforms with variable sediment texture

    • Interlobate complex (supra-glacial till)
    • Moraine areas
    • Collapsed stream sediment

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Farm island

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Donjek Glacier Outburst�

Possible Depositional Setting

Looking downglacier through the ice canyon. The canyon walls are roughly 30 m high and the channel width roughly 50 m.

http://www.eos.ubc.ca/research/glaciology/album/DonjekFlood/index.html

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Tunnel collapse, ice-walled and ponding water

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Landforms with finer texture

    • Lake plains - blue
    • Subglacial till - green
    • Some areas of supraglacial till – light green

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Aitkin Sand and Gravel Map

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Bedrock simplified

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Questions that I have

What is the detailed glacial stratigraphy and how does water move through these layers?

  • Where is water recharged
  • What is the flow path
  • How old is the water

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How does water move through peat?

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Does the current sampling strategy adequately address the way water is held and altered as it moves through peaty materials?

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�What is the impact of high dissolved organic carbon and low pH on movement of metals?�

Sarah Elliott

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Relevant USGS publications

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MGS sources for lithostratigraphy and till geochemistry

https://conservancy.umn.edu/handle/11299/177675

https://conservancy.umn.edu/handle/11299/123358

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MGS sources

https://conservancy.umn.edu/bitstream/handle/11299/210181/MGS%20Open%20File%20Report%20OFR-19-2.pdf?sequence=1&isAllowed=y

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Maurice Nguyen, Minnesota Geological Survey

  • 612-626-5437
  • nguyenm@umn.edu

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Forthcoming Aitkin County Geologic Atlas

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Vanessa Baratta, DNR�

vanessa.baratta@state.mn.us

 651-259-5685

Ongoing sampling for Aitkin County Geologic Atlas, Part B

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DNR Tribal Liaison

Bradley Harrington

bradley.harrington@state.mn.us

Cell: (320) 515-0688

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Annotated references

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