ABSTRACT: Glacier observations in the Torngat Mountains, Northern Labrador.

CGRG Bibliography of Canadian Geomorphology
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Cirque glaciers in the Torngat Mountains of northern Labrador are the only glaciers on mainland Canada east of the Rocky Mountains and represent thesouthernmost limit of glaciers in the eastern Arctic. A compilation of recent inventories suggests that there may be as many as 86 ice masses in the Torngat Mountains, though not all of them are strictly glaciers. The largest glaciers are <2 km2 in area and tend to be shaded by high cirque backwalls. The earliest detailed observations were made by Edward Bryant and Henry Forbes on Bryant’s Glacier in the Four Peaks range in 1908. Their photographs of the glacier snout were used by Noel Odell during a subsequent visit in 1931 to calculate a retreat rate of ~3.5 m a-1. Mass balance studies on four glaciers in the Selamiut and Cirque Mountain ranges by Robert Rogerson between 1981 and 1984 indicated an overall negative balance, averaging -0.26 m. Abraham Glacier was the only one of the four that measurably re-advanced (1.2 m a-1) during the monitoring interval. A new initiative to measure glacier change in the Torngat Mountains National Park is part of ArcticNet’s Nunatsiavut Nuluak project and operates in partnership with Parks Canada and the Nunatsiavut Government. It has as its primary goal to establish a baseline of current glacier conditions to be used for future monitoring, recentchange detection and local hydrological assessment. The research plan involves remote sensing, field surveys and local knowledge from Inuit elders who lived and travelled in the Torngat Mountains. Field activities in 2008 focused on some of the glaciers previously studied by Rogerson in the early1980s. Precise surveys of glacier surface elevation and margin position were carried out on Abraham, Hidden and Minaret glaciers using a differential global positioning system (DGPS). DGPS was also used to measure a selected number of static points on stable, non-moving (i.e. rock) terrain surrounding the three glaciers. These points, which are identifiable in metric vertical aerial photographs, are used as three-dimensional ground control points, essential to deriving stereo-photogrammetric measurements of surface elevation. The high-quality DEM surfaces of each glacier and its surrounding terrain will be compared with archival elevation data sources (e.g. satellite laser altimetry from the Geosciences Laser Altimeter System (GLAS) aboard NASA’s Ice, Cloud and land Elevation Satellite (ICESat)). Glacier surface elevation data are complimented by bed topography derived from ground penetrating radar(GPR) data. These data, once filtered, processed, and topographically-corrected (using DGPS elevations along coincident survey lines) will provide accurate bed elevations which may be subtracted from surface elevations to measure ice thickness. These data may be used to estimate total ice volume and in combination with repeat surface elevations to measure volume loss over time. Preliminary highlights of the 2008 data indicate significant ice marginal retreat, on the order of 100s of metres, over the last 25 years. Bryant’s Glacier, for example, which was re-photographed in 2008 from the same location as in 1908, shows substantial loss in ice volume.

Bibliography of Canadian Geomorphology