Frederick E. Nelson

PERMAFROST ZONATION IN EASTERN CANADA: A REVIEW OF PUBLISHED MAPS

Large discrepancies in placement of zonal “boundaries” are apparent between maps depicting the areal extent of permafrost in the Hudson Bay region. Although progressive improvements in data availablility are apparent through time, many of the differences between maps are attributable to a lack of explicit mapping criteria, to ambiguous or conflicting definitions of permafrost “continuity,” and to the widely recognized lack of observational data. The term “continuous permafrost” should be used only with reference to small (e.g., subcontinental) geographical scales, in which zonal tendencies are apparent. Cartographic depictions should be based on well-defined mapping criteria. [Key words: permafrost, cartography, eastern Canada, frozen ground.]

SPECTRAL SIGNATURE OF COUPLED FLOW IN THE REFREEZING ACTIVE LAYER, NORTHERN ALASKA

Soil temperature records obtained from the active layer above permafrost at a site in northern Alaska during autumn and winter have variance spectra inconsistent with a purely conductive heat-transfer system. Although conductive heat-transfer theory predicts that temperature fluctuations are attenuated with depth, sub-diurnal thermal variance at the 50-cm level, near the base of the active layer, exceeded that at the 10-cm level. Short segments of the temperature record were drawn from three distinct periods of soil-frost conditions: (1) at the maximum vertical development of the active layer in early autumn; (2) during frost penetration and the formation of a zero curtain in early winter; and (3) after freezeback of the active layer. The variance spectra of these time series show systematic seasonal transitions that reflect changing mechanisms of heat transfer. During the first and second periods, heat transfer by internal evaporation and condensation dominates at wavelengths in the diurnal range. The sp...

Bibliographic Instruction in the Undergraduate Research Methods Course.

Abstract Bibliographic instruction is aneglected component of undergraduate education in many geography curricula. Significant research problems are difficult to formulate and self-education cannot be achieved without the ability to use reference materials effectively. The research methods course is a logical vehicle for providing bibliographic instruction at the undergraduate level. Library training can be incorporated in this course through a series of instructional modules that requires students to work with a wide variety of bibliographic materials. Students should be allowed to focus on publications pertaining to topics of individual interest in all phases of their work. This paper outlines a methods course that emphasizes bibliographic instruction and gives suggestions for incorporating selected developmental materials.

FROST MOUNDS AT TOOLIK LAKE, ALASKA

Aggradation palsas and seasonal frost mounds can achieve topographic expression by localized pooling and freezing of water within the active layer. A distinction is drawn in this paper between palsas, which are permafrost landforms by definition, and seasonal frost mounds, ephemeral or oscillatory features surviving for less than 2 years. Subsurface water migration occurs in response to positive or negative pore water pressures generated during active-layer refreezing. Upward deformation results from stresses induced by the local addition of water and subsequent phase change and, in some cases, positive pore water pressures. In the absence of site instrumentation, processes associated with mound formation can be inferred by examination of massive ice cores, where a record of the aggradational event is preserved. Stratigraphic and petrographic characteristics of the core, ionic concentration patterns with respect to depth, and mound morphometric data were obtained for a large ice-cored frost mound which de...

METHODOLOGY: A DEVICE FOR MONITORING SOIL MOVEMENT IN PEATLANDS

Traditional methods of tracking soil movements may be unreliable in soils containing a large proportion of organic matter owing to the composition and mechanical properties of peat. A simple, inexpensive, and reusable “anchored” target can be used to monitor both vertical and horizontal components of soil movement in fibrous peat. The target is unlikely to be affected adversely by flooding, frost heave, or animal disturbance, and is applicable to a wide range of geomorphic problems in peatlands. [Key words: frost heave, peat, peat landforms, soil movement, survey targets.]