Glaciology

Geology

Climbing

Trek

Science The planned scientific programme had two components. The first, a study of a glacier confluence; the mechanics of confluences have been studied only very rarely, and never before in this area of the world. Our target is to understand how this particular glacier system operates and analyse it with comparison to similar systems in other areas of the world. Secondly, we carried out a geological mapping exercise - the most detailed survey of the area so far.   Glaciology Initial objective Ice flow is affected by the surrounding topography and the climate in which the glacier is situated; for example, valley glaciers move differently to large ice sheets. Thus by studying different systems in new locations, we can add to the picture of how ice masses move, and may move in the future, with potential implications for the effects of climate change.   In terms of results, we hope to model the flow field for the ice mass around the confluence area, and thus classify the glacier as cold-based (ie. frozen to the bed) or polythermal (ie. the glacier has some warmer layers within it). Our research will hopefully therefore be a useful reference for further work, both on confluences and climate effects.   Methodology The strain rate of the ice flow will be measured throughout the study area by creating a series of cells using an array of carefully located stakes. Their motion relative to one fixed point will be measured with time, using a Geodometer theodolite. With reference to a further fixed point, it will be possible to assess the relative vertical motion of the stakes, and thus calculate any uplift that may occur.   Measurement equipment layout Initially, the positions of stakes will be measured twice daily, to assess the rate of glaciar motion. If there is no evidence of flow on such short timescales then positioning will be carried out daily or every two days. The remaining time will be spent on geological mapping.   Using a triangular grid system gives the most efficient system, reducing the weight of equipment required. We will use hollow, rigid, high-density plastic pipes as stakes (instead of the more traditional wooden dowel). this has often been done where weight is an important consideration. Comment 1 Point of Measurement. Theodolite will be set up here initially and all measurements wil be made relative to this point. 2 Grid of Stakes. Each point marks the position of a stake, and each line the relative distances between them. 3 A secondary fixed position will allow us to measure height changes through time and identify any areas of uplift or subsidence. 4 Each stake is accurately placed and its position measured from the main theodolite. Each stake is fitted with a reflective prism before measurement to ensure accurate location of the top of the stake. 5 Two stakes are positioned right at the edges of the glacier, one on each side. The motion of these will be analysed to test for any sliding at the base of the glacier. [Back to top]   Data Analysis The two principal strains, shear strain and components of down-glacier strain will be calculated using a computer code that calculates relative movements from inputs of position. The programme will also give us a measure of the errors involved. The original FORTRAN code, supplied by the Department of Geography, will be specially modified to account for the specific layout of our stakes.   Post-expedition report We were unable to reach our target confluence since the route towards it was too dangerous. We managed to locate nearby (within 1 day) a second suitable confluence which were were able to reach with ease, and we commenced our glaciology work there. Although the situation was less clear-cut than the initial site, initial analysis of our reults shows a good correlation to expected flow patterns. The Total Station was able to measure distances of nearly 1km reliably - 250m greater than the width of the incoming glacier systems being measured. Stakes experienced significant measurable movement throughout the three-week period (around 60cm in the speediest case). Further analysis can now be completed since the expedition has returned to the UK, taking account of all forms of measurement we were able to achieve. Detailed results will be posted once they are available.   [Back to top]   Geology Initial objective The main body of previous geological work on the inland parts of northeast Geenland consists of 1:500 000 scale mapping by the Geological Survey of Denmark and Greenland (GEUS). This involved camps at the edges of two fjords to the south and east of Louise Boyds Land, together with some spot landings and helicopter mapping. This programme was completed in 1997. Our own geological mapping programme has been planned with the help and resources of the GEUS, and we plan to complement their large scale mapping with 1:100 000 scale, (and possibly 1:50 000 scale), more detailed work from the ground. This work may then be used in future publications from the Survey. We aim to cover a total area of roughly 50km2, bearing in mind that outcrop is as nunataks between glaciers.   Based on previous work, it is likely that most of the rocks in the are within the upper thrust sheet as mapped by GEUS. We are expecting to find metasediments from the Mesoproterozoic Krummedal succession, cut by a variety of younger (930 Ma) granites, some Caledonian (425-425 Ma) granitic sheets, and a couple of thick, folded metadolerite dykes. This information is derived from a single helicopter fly-by and single spot landing; there is thus a lack of any detailed information on the area. The main focus of our mapping, apart from a detailed examination in outcrop of the main lithologies observed, will be to determine the intrusion relationships of the dykes and two generations of granites, to determine the nature of the fold structures, and their relationship to the intrusions.   These are ambitious projects that have been devised with the help and advice of Dr. Ian Willis (Department of Geography, University of Cambridge), Prof. Mike Hambrey (Institute of Geography and Earth Sciences, University of Wales, Aberystwyth), Dr. Andy Whitham (CASP) and Dr. Peter Friend (Department of Earth Sciences, University of Cambridge).   Post-expedition report We were able to provide some detailed analysis of the geological structure of the target site via a 4-day excursion to the area during which we were able to answer several questions left by the helicopter visits. We were able to provide information on the geology of the area around our new science camp although work available in this area was limited. [Back to top]   Climbing Initial objective The eastern part of Louise Boyds Land is previously unvisited from the ground and here are four unclimbed summits at 2010m, 2010m, 2400m and 2285m. These are all within an 8km radius of our intended base camp (see aerial photo). First ascents will be attempted on all of these after the completion of the fieldwork. The climbs should be well within the capabilities of the team. The climbs will be led by the team's Mountain Leader.   Post-expedition report We were able to complete several climbs with a wide range of techniques in the new science area. We completed three rock routes on the ridge below which we were camped, and two ski-climbs each incorporating two summits. We achieved a total of 7 first ascents over 6 routes. [Back to top]   Trek Initial objective The final phase of the expedition is a long trek, pulking (pulling sledges with all our equipment) about 200km down the Greenland Icecap to a pick-up point South of Petermann Bjerg. We hope to complete this in 10 days to two weeks; 20km per day being a realistic estimate of performance.   Post-expedition report Poor snow conditions lowered our daily coverage to under 3km in some cases and we were plagued by obstacles and equipment faliures. Nevertheless we were able to cover the 200km required distance in the required time, navigating on to the greenland Ice-cap before traveling a short distance overland to be picked up by boat. [Back to top]   ©Derek Marshall for Cambridge Greenland Glaciology Expedition 2002