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Till fabric analysis and origin of Portage Glacier Little Ice Age moraines, south-central Alaska
Polar Geography (2012)
  • Dr. João A. Santos, Universidade de Coimbra
  • Lucio Jose Cunha, Universidade de Coimbra
Abstract
Observations of geomorphic and sedimentary processes occurring in modern glaciers allows interpretations of the genesis of older glacial deposits and landforms and has led glacial geomorphologists and geologists to place a greater emphasis on studies of glacial sedimentology. This research investigates the genesis of Little Ice Age (LIA) moraines present in Portage Glacier Valley, 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 primarily 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 of Portage Glacier in AD 1900 and AD 1922.
Disciplines
Publication Date
2012
DOI
10.1080/1088937X.2012.663413
Publisher Statement
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Citation Information
João A. Santos and Lucio Jose Cunha. "Till fabric analysis and origin of Portage Glacier Little Ice Age moraines, south-central Alaska" Polar Geography Vol. 35 Iss. 1 (2012) p. 65 - 81
Available at: http://works.bepress.com/joao-santos/4/