During the summer of 1969 a thermal drilling and deep ice-temperature measurement program was carried out on the Fox Glacier, Yukon Territory. The thermal drilling resulted in seven instrumented holes at six locations on the glacier, three reaching bedrock. Temperature measurements indicated that the glacier was below the pressure-melting point throughout and that memory of a disturbed thermal regime existed. Estimates of geothermal heat flow were determined and an anomalous value of 4.73 μcal/cm² sec obtained. Bottom temperature models were developed which indicate the possibility of basal melting. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

A high-resolution radio echo sounder operating at a frequency of 840 MHz has been developed for sounding of small and medium-sized polar glaciers and ice caps. The sounder uses a compact, high-gain antenna which improves the system performance, suppresses valley wall echoes and simplifies operation from light aircraft. Successful field trials were carried out on the Rusty, Trapridge and Hazard Glaciers, Yukon Territory, Canada. Results of airborne surveys compare well with ice depths obtained from earlier ground-based soundings on the Rusty and Trapridge Glaciers. The maximum ice thickness encountered was 200 m on Hazard Glacier. Owing to the high operating frequency, random scattering from inhomogeneities within the ice is a major cause of signal degradation. For this reason the sounder cannot penetrate great thicknesses of temperate or debris-rich ice. Spatial averaging, an immediate result of operating from a moving platform, reduces the effects of back-scattered "clutter. " Results of ground-based tests on the Hazard Glacier yield a value for ftan 8 = 0.26 at -50C, in agreement with predicted values. The total received power and the echo details have both been found to be very sensitive to small (<<I0 cm) changes in antennae position. Large fluctuations in power, caused by roughness at or near the ice/air surface, prevented using single coverage data to detect birefringence in glacier ice. The results also indicate that the standard photographic records should be replaced by a recording medium capable of storing more precise and accessible data. A storage medium such as magnetic tape should not degrade the radar data, and would at the same time relieve a data processing burden. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Valley glaciers often occur within complex dendritic systems where tributary glaciers contribute ice mass and blocking potential to the trunk glacier. Analysis of glacier inventories and maps in the regions of Svalbard, East Greenland, Yukon Territory and the Thompson Glacier system indicates that trunk - tributary intersections commonly occur at angles between 45° and 90°. An analogue material with flow properties similar to creep in pure ice has been used to simulate flow in a model valley glacier. The model and a series of blockages were constructed based on dimensions derived from the inventory and map analysis. The angled blockage indicates lower overall velocity rates and appears to have a funnelling rather than blocking affect on the analogue material. The perpendicular obstruction that blocked half the width of the model valley caused a piling up of analogue material prior to a release into the unobstructed side of the valley. / ix, 149 leaves : ill. ; 29 cm.

Five periods of ice advance in the North Klondike-upper Blackstone basins of the Ogilvie Mountains are recognized by the downvalley sequence of progressively older moraines. The youngest occurred during the last millennium and is represented by glacierets and fresh moraines. The other advances are of the Pleistocene Epoch; from youngest to oldest they are: Age I (valley glacier stage), Age II (transection glacier), Age IIA (transection glacier with piedmont) and Age III (mountain ice cap). Evidence for Age III is limited to the north slope of the ranges. Age IIA was recognized only on the north slope and may represent a slightly older pulse of the Age II. This chronosequence is tentatively correlated with those elsewhere in the northern Cordillera. Within the region an array of surficial elements indicates that a continuous and discontinuous mosaic of processes have operated interdependently during the Quaternary. A product of these processes is mapped under one of eight facies - attention being directed to the varieties of features associated with the glacial and periglacial cycles. Of the latter, active, inactive and degradational forms exist. Strong correlations between the distribution of some types of surficial features and the underlying bedrock geology are recognized. No changes in morphology, permafrost distribution, pebble weathering, pedogenesis and floral succession could be related to the ages of the Pleistocene moraines. The influence of permafrost on all ages of moraines, the variability in their environment of deposition, and an edaphic and climatic discontinuity produce greater differences than does the age factor. In the northern half of the study area, permafrost and associated phenomena were observed to greatly retard chemical alteration; on the other hand, they permit the development of only a vegetational and pedological "polyclimax", rather than a single mesic climax, in a time span of less than 11,000-15,000 years. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate