Soils and Geomorphology in the Oregon Cascades: A Comparative Study of Illinoian-Aged and Wisconsin-Aged Moraines

Catena approaches to soil chronosequence studies in the Oregon Cascades are lacking in the literature. Here we compare pedogenesis with slope position on two different aged moraines. The younger Suttle Lake moraine (11 to 20 ka B.P.) contains a sequence of pyroclastic teprhas overlying glacial till...

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Bibliographic Details
Published in:Physical geography 2006-07, Vol.27 (4), p.363-377
Main Authors: Haugland, Jake E., Burns, Scott F.
Format: Article
Language:English
Subjects:
Bgi / Prodig
catena
chronosequence
Oregon Cascades
pedogenesis
Pedogenetic processes
Pedology
Physical geography
Profile Development Index
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Summary:Catena approaches to soil chronosequence studies in the Oregon Cascades are lacking in the literature. Here we compare pedogenesis with slope position on two different aged moraines. The younger Suttle Lake moraine (11 to 20 ka B.P.) contains a sequence of pyroclastic teprhas overlying glacial till and subsequently a series of buried soils. The older Jack Creek moraine (120 to 200 ka B.P.) is predominantly uniform in its parent material, glacial till. Both moraines show evidence of upslope erosion and down-slope deposition, being more active on the younger Suttle Lake moraine. Major differences in soil properties between the two moraines are associated with texture. Pyroclastic parent material is much coarser, with textures of sand and gravel, while older glacial till parent material typically displays a texture of loamy sand. Percent organic matter is higher in the finer glacial till. Harden's Profile Development Index values (i.e., PDI) were used to compare B-horizons of similar glacial till parent material. The PDI is of limited use in this study due to volcanism and glaciations producing alternating layers of parent material. However, B-horizons of similar parent material did obtain higher values on the older Jack Creek moraine. The index was also useful in identifying a much older buried B-horizon at the toeslope of the Suttle Lake moraine, possibly comparable to that of pre-Bull Lake-aged deposits in the Rocky Mountains. The use of soils as relative age indicators is cautioned for future work in the Oregon Cascades due to the complexity associated with an active volcanic landscape.
ISSN:0272-3646
1930-0557
DOI:10.2747/0272-3646.27.4.363