Preliminary observations of nivation processes, Cathedral Massif, Northwestern British Columbia, Canada

ABSTRACT

Nivation, the suite of weathering and transportation processes attributed to late-lying snowpatches, is linked to the formation of cryoplanation terraces (CTs). CTs resemble giant staircases arranged in repeating sequences of low-gradient treads and steep scarps that extend over hundreds of meters. The nivation hypothesis of CT development has been supported in recent literature examining weathering and erosion trends, but the mechanisms involved in transporting sediment across CT treads remain underinvestigated. Sorted stripes, a type of patterned ground encountered on CT treads, have been linked to efficient snow meltwater flow across low gradients, indicating that these features could be an important component of CT formation. In this study, we use short-term soil thermal and moisture records, particle-size analysis, and apparent thermal diffusivity calculations to examine periglacial processes operating on two incipient CTs. Initial results indicate that: (1) the coarse (boulder and cobble size) portions of sorted stripes function as subsurface channels for sediment transportation across gently sloping CT treads (generally < 12°) by flowing water; (2) hillslope hydrology is an important component of the erosion processes sculpting upland periglacial environments; and (3) late-lying snowbank environments are highly dynamic during warm weather, with large amounts of sediment transported over short periods.

KEYWORDS:

• Cryoplanation
• British Columbia
• fluvial processes
• hillslope hydrology
• nivation
• periglacial processes

Acknowledgments

Research funds used to conduct this work were provided by the Michigan State University (MSU) College of Social Science and Department of Geography, Environment, and Spatial Sciences. We extend our thanks to the Juneau Icefield Research Program for use of its research facilities, and to Northern Michigan University for provision of a research vehicle. Discovery Helicopters Ltd. of Atlin, British Columbia provided logistical support. We are grateful to MSU Professor Randall Schaetzl for use of his soils laboratory for sedimentological analyses. Thanks to MSU Professors Alan Arbogast and Ashton Shortridge for their advisement on RJM’s master’s thesis, upon which this paper is based. FEN expresses deep gratitude to the late Professor Antony R. Orme for professional support and advice over a period of more than three decades.

Disclosure statement

F.E. Nelson is a member of Physical Geography’s editorial board.