Mount Logan Glaciology Project. Our party members were M. Demuth, R. Glykherr, B. Sheffield, G. Ferguson and me. Beginning on May 9 on the upper Quintano Sella Glacier, we dug and sampled snow pits at Base Camp, King Trench, King Col, Northwest Col and AINA Peak at 2875, 3350, 4200, 5340 and 5630 meters respectively to study snow chemistry variations withaltitude. In particular, we were also interested in detecting Chernobyl reactor and Augustine volcano fallout. (The 285-year-long Northwest-Col core shows a history of atmospheric nuclear-weapons testing and volcanic fallout.) All samples were brought down on skis or hauled out on sleds. On the Northwest Col a camp was established and a 6.4-meter dig made down to the 1980 borehole casing, which we now plan to relog in 1987. A series of air samples was taken for CO2 measurements, which data will compliment the CO2 measurements made on the air bubbles contained in the ice core, extending from about 1800 AD to 1950 AD. On June 6 Sheffield and Ferguson climbed to the summit on Mount Logan (5951 meters, 19,524 feet) during a rare spell of good weather. The descent was slowed because it involved the sledding and back-packing of equipment down to King Col for helicopter pickup. Limited (fly-in only) helicopter support to 5300 meters restricted our research work this year. Helio- courier support went only to King Trench. We also installed a bronze plaque on Prospector’s Col at 5475 meters to the memory of the late aviator, Philip Upton. The figure shows the results of some of the analyses that are available from this project.

Radioactivity and chemical analysis of snow pit samples from the head of the Donjek Glacier at 3017 meters about 45 kilometers north of Mount Logan. The late March-early April eruption of Augustine volcano in southwest Alaska is recognized by the high chloride and sulfate peaks. The eruptive gases were known to have been high in hydrogen chloride and this result confirms the fact. Nitric acid, represented by most of the nitrate ion present, shows a weak (spring) response but this is not associated with any specific event. Following closely after the volcanic signature is a radioactive peak which is considered to be from the late April Chernobyl reactor explosion in the USSR. The radioactive cloud was known to have reached western Canada on 9 May 1986. A similar snow pit on Mount Logan at 5340 meters was sampled in the same way and analysed for the same species but there were no signals from either events that show any significance. This suggests that both radioactive and volcanic acid clouds were largely confined to the lower troposphere, at least in northwestern Canada.

Gerald Holdsworth, Arctic Institute of North America