July 22, 2022
Driller Johannes and logger Anders inspecting the NAAZ II layer in the loggers cabin.
The first ice-core run of the day contained a well-known visible ash layer that is found in all deep Greenland ice cores: the North Atlantic Ash Zone (NAAZ) II. The volcanic source of the layer is known to be situated in Thórsmörk in southern Iceland. The ash layer is widespread in the North Atlantic region and serves as an important time marker linking ice cores with marine and lake sediment records beyond the range of C-14 dating. According to the Greenland ice-core chronology, the ash layer has an age of 55,400 years; whereas a recent Ar-Ar dating of the ash layer based on material from Iceland suggests an age of 56,100 years. In the ice core, the NAAZ II ash layer is one of the most prominent out of a handful of visible ash layers in the 120,000 years covered by the ice cores. The brownish ash layer that is a few mm thick appears somewhat reworked in the core with agglomeration of smaller particles. This may be a result of ice deformation in this deep part of the ice sheet. One has to imagine the entire Greenland ice sheet being covered by ash at the time of the eruption. Not the type of eruption that we would like to experience today.
What we did today:
Weather today: Overcast most of the day, windy and warm conditions. Clearing up during the evening. Temperatures -14.4 to -2.1°C. Wind: 6-14 kt from SW.
FL, Anders Svensson
Close-up of the ash layer.