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MELTWATER PROCESSES & LANDFORMS

A. Introduction

Learning outcomes - You should be able to:

Readings:


B. Meltwater Erosion & Transportation

Meltwater stream photo credit: M. Rhinard. 2009. PolarTrec - Glacier Tramping.
Meltwater sediment photo credit: K.A. Lemke.

Photo: sediment-laden  meltwater stream Mechanical erosion

Chemical erosion: solution

Photo: meltwater sediment, Wisconsin Transportation


C. Supraglacial Meltwater Deposition & Landforms

Deposition

Photo: varves Ice-walled lakes Link: topographic map ice-walled lakes & kames

Photo credit: NAGT Cutting Edge Workshop: Teaching Climate Change from the Geologic Record.

Kames

Photo: moulin kame, Wisconsin

Photo credits: K.A. Lemke. Moulin kames in Wisconsin.

Photo: moulin kame, Wisconsin Photo: mouline kame sediments

Kame and kettle topography; stagnant ice

Photo: kames viewed from Parnell Tower, WI
Photo credit: K.A. Lemke. Kames viewed from Parnell Tower, Wisconsin.


D. Sublacial Meltwater Deposition & Landforms

Photo: Wisconsin eskerTunnel Deposition

Eskers and crevasse fills


E. Ice Marginal Meltwater Deposition & Landforms

Ice marginal deposition

  • proximal zone

    • meltwater redistributes & redeposits melt-out till

    • highly variable flow regime - rapid discharge fluctuations

    • sudden deposition of all sediment - minimal stratification or sorting

    • difficult to distinguish from melt-out till & flow till

  • medial zone

    • braided river pattern (multiple impermanent bars and channels)

    • sediment grain size decreases with distance from the glacier

  • distal zone

    • much finer grained

    • more likely single-strand than braided (multi-strand)

    • less temporal variation in flow

Photo: proximal zone deposits, Franz Josef Glacier, New Zealand

photo: medial zone braided river

Image credit: Mark Emery. US Fish & Wildlife Service Digital Library System
http://images.fws.gov/default.cfm?library_id=none&CFID=3302570&CFTOKEN=37370443

Outwash fans

Map: outwash fan & end moraine,
USGS topographic map: Arnott, Wisconsin

Photo: pitted outwash Outwash plain

Image credit: B. Molnia. Earth Science World Image Bank image hfz45a.

Kame terrace

Photo: outwash plain central Wisconsin.
Photo credit: K.A. Lemke. Outwash plain, central Wisconsin.


photo: ice marginal lake, Tasman Glacier, 
New ZealandF. Lacustrine Deposition

Ice-marginal lakes, proglacial lakes

Deposition from:

Lakes dominated by ice-rafted debris

photo: iceberg in ice marginal 
          lake, Tasman Glacier, New Zealand photo: till overlying 
          lacustrine sediments
Image credit: ©Bruce Molnia, Terra Photographics. Image source: Earth Science World Image Bank http://www.earthscienceworld.org/images

Lakes dominated by settling of suspended sediment


Photo: braided outwashG. Summary

Meltwater erosion, transportation & deposition

Meltwater deposits & landforms

 

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©Karen A. Lemke: klemke@uwsp.edu
Last revised March 24, 2014