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Article
Distinguishing Lodgment Till from Melt-Out Till using Till Fabric and Grain Size Analysis: A Case Study in Portage Glacier Little Ice Age Moraines, South-Central Alaska.
Portuguese Quaternary Association Programs and Abstracts, 1st International Conference. (2011)
  • Dr. João A. Santos, San Jose State University
  • Lucio Jose Cunha, Universidade de Coimbra
  • Carlos E. Cordova, University of Coimbra
Abstract
The study of glacial landforms and deposits is important, as it is difficult to observe processes under modern glaciers and ice-sheets. Thus landscapes and sediments that are the product of present-day glaciation can give insight into processes that occurred during Pleistocene times. This study investigates the genesis of Little Ice Age moraines present in Portage Glacier, South-Central Alaska using till fabric and grain size analysis. The present-day moraine morphology and sedimentology in Portage Glacier Valley reveals the presence of two types of till and moraines. The clast-rich medium to coarse sandy diamicton present in the AD 1852 moraine is interpreted to be a lodgment till indicating that this feature is a Type A push moraine representing glacial advance of Portage Glacier prior to AD 1852. The clast-rich coarse to very coarse sandy diamicton present in the AD 1900 and AD 1922 moraines is interpreted to be a supraglacial melt-out till (ablation till) indicating that these features are ablation moraines representing glacier recession and moraine building in AD 1900 and AD 1922
Keywords
  • Glacial Geomorphology,
  • Till Fabrics,
  • Portage Glacier,
  • South-Central Alaska
Disciplines
Publication Date
December, 2011
Citation Information
João A. Santos, Lucio Jose Cunha and Carlos E. Cordova. "Distinguishing Lodgment Till from Melt-Out Till using Till Fabric and Grain Size Analysis: A Case Study in Portage Glacier Little Ice Age Moraines, South-Central Alaska." Portuguese Quaternary Association Programs and Abstracts, 1st International Conference. (2011) p. 29
Available at: http://works.bepress.com/joao-santos/15/