Rediscovery of marks established by Johan Bernhard Rekstad around the turn of the 20th century to measure frontal variations of outlet glaciers from Jostedalsbreen Ice Cap in western Norway

Around the turn of the 20th century, the first state geologist at the Geological Survey of Norway, located in Kristiania (Oslo) at that time, Johan (also sometimes named John) Bernhard Rekstad established a series of marks, mostly crosses carved into boulders and bedrock slabs. These marks formed the basis for frontal measurements of outlet glaciers from Jostedalsbreen Ice Cap in western Norway. In total, he carved 29 marks in front of 15 outlet glaciers around the ice cap. For only a few of these marks, the exact locations have been known until recently. Therefore, the authors started a search for these marks some years ago, as they may provide valuable information on glacier frontal changes since their time of establishment. At present (2025), 18 marks in front of 12 different outlet glaciers from Jostedalsbreen Ice Cap have been rediscovered and documented by exact locations (coordinates and altitude) and photographs.