A field survey of the properties of rock glaciers in Hopsfjorden. A study of their relation to local geomorphological conditions

• Main Author: Slinde, Gaute Grindheim
• Format: Master Thesis
• Language: English
• Published: 2020
• Subjects: Hopsfjorden; Norway; Store Skogfjorden; Finnmark; glacier; Ice; permafrost
• Online Access: http://hdl.handle.net/10852/85335; http://urn.nb.no/URN:NBN:no-87852

In this thesis the rock glaciers and geomorphology of the three fjord arms of Hopsfjorden called, Ivarsfjorden, Store Skogfjorden and Lille Skogfjorden were surveyed. Hopsfjorden is located in Finnmark at 70.9° N and 28° E. Hopsfjorden is home to several rock glaciers located along the shore of the fjord. Some of these rock glaciers appear to be active. While several rock glaciers in Norway are active, the potentially active rock glaciers in Hopsfjorden are the only ones that are located this close to the shore. Hopsfjorden is remote and as a result it has not been surveyed from the ground in a long time, and the available geomorphological map of the area is not detailed. The thesis therefore aims to determine if some or any of these rock glaciers are active, why some are active, and some are not, and to make a detailed geomorphological map of Hopsfjorden. To create a geomorphological map of the fjord arms of Hopsfjorden a total of 10 days in the field was used to collect observations and document landforms and surface material. These observations became the basis for the geomorphological map. Only Ivarsfjorden and Store Skogfjorden was visited during the field observations. Lille Skogfjorden was therefore mapped entirely based on arial photographs and some small observations made when sailing past the mouth of Lille Skogfjorden. Arial photograps was also used to complement field observations in the other fjord arms. To determine if an active rock glacier existed in Hopsfjorden it was attempted to prove that one of the rock glaciers had permafrost and moved. Therefore, an electro resistivity tomography (ERT) survey and a seismic reflection survey was preformed on one of the rock glaciers, the Ivarsfjorden rock glacier, to determine if permafrost was present in the rock glacier. Vertical and horizontal change detection based on drone images was used to determine if the rock glacier is moving. Field observation and temperature measurements at key locations were used to compliment the geophysical and change detection findings. Such extensive survey of a rock glacier was only possible on Ivarsfjorden rock glacier as this was the only rock glacier with a road connection. The survey to determine if Ivarsfjorden rock glacier was active, indicated that the rock glacier was inactive and not moving, but probably containing some permafrost. The combined results of the ERT and the seismic reflection survey indicated no permafrost. The horizontal change detection showed no significant movement, the vertical change detection showed signs of the rock glacier losing height. The field temperature measurements indicate some areas as having ice due to the discovery of negative degrees, and field observations found furrows and ridges that may indicate that movement has occurred on the rock glacier. From this, I suggest that while Ivarsfjorden is inactive, it is possible that this is a very recent development The geomorphological map resulting from the field survey of the fjord arms, gave a higherlevel of details than what was previously available. The field observation taken while creating the map also showed that what was potentially active rock glacier and was potentially inactive rock glaciers in Hopsfjorden, were not randomly located. Their locations correlated with a change in bedrock material and a change in slope processes. The potentially active rock glaciers were created on blocky material, while all the potential inactive rock glacier was created by pebbly material. The different creation of the active and inactive rock glaciers probably effects the isolation properties of the blocky fields of the rock glacier. This could explain why the pebbly rock glaciers seem to be inactive or relict, while the Blocky rock glacier appear to be potentially active or at least change to inactive rock glacier much more recently than the pebbly rock glaciers.