Subglacial investigations at Bondhusbreen, Folgefonni, Norway

From tunnels in the bedrock under the Bondhusbreen glacier almost vertical shafts were driven up to the ice/bedrock interface in order to collect the water in the subglacial streams. The observations described here were carried out in artificial ice tunnels melted out along the bottom of the glacier. The ice thickness above the intakes was 160 m. Ten pressure transducers were mounted in different constructions to measure the ice pressure on the bedrock. Stagnant ice with almost isotropic pressure as well as dynamic effects was observed. The temperature at the ice/bedrock interface was measured on the stoss and lee sides by thermistors in the pressure transducers. The subglacial water transports more than 90% of all material under the glacier. The total debris flux in the ice was estimated to 450 metric tons per year, which was only 5–8% of the total load transported by the water. Various other observations of rock deformation, striae, P-forms, brown skin, water pockets, ice crystals and ice chemistry will...