APPLICATION OF THE SCHMIDT HAMMER RELATIVE AGE DATING TECHNIQUE IN ICELAND

While the glacial history of Iceland is well studied, critical gaps in the reconstruction of ice flow throughout the Quaternary remain. The timeline of moraine formation is not well-constrained in parts of the country, particularly the arid region north of Vatnajökull. In this study, we aim to elucidate the glacial history of part of Iceland using the Schmidt Hammer (SH) dating method. We also assess the efficacy of the SH as a relative and numerical dating tool. We used the SH at five locations across Iceland: two bedrock sites with glacial erratics (Borgarvirki and Vopnafjorður) and three morainal deposits (Skessugarður, Fiskidalsháls, and Fláajökull). Previous studies suggest that these sites range in age from Younger Dryas to Little Ice Age (LIA). At least 10 surfaces were tested per site and at least 10 impacts were measured per surface. Significant differences in the median rebound values between Borgarvirki (r = 48.5) and the Skessugarður (r = 52.5) and Fiskidalsháls (r = 55.5) moraines show that sites closer to the modern ice margin are younger. The Vopnafjorður median rebound value (r = 51.5) was not significantly different from any of the other northern sites, indicating possible rapid ice retreat north of Vatnajökull. We tested the SH technique on two moraines on the Fláajökull morainal complex south of Vatnajökull. The significant difference in the median rebound values of the outermost (LIA) moraine (r = 65.3) and an inner (1945 A.D.) moraine (r = 70) matches the known relative age order of these moraines. These rebound values are significantly higher than northern Iceland sites, demonstrating that the SH technique provides reliable relative ages for moraines. A calibration curve of rebound values for northern Iceland was constructed using cosmogenic radionuclide dates from the area south of Húnaflói Bay. This curve was used to estimate ages for Vopnafjorður, Skessugarður, and Fiskidalsháls. In ongoing work, these ages will be compared to new CRN dates of the same surfaces to assess the accuracy of the SH in numerical age dating. SH rebound values provide relative ages of retreat of the Iceland Ice Sheet, presenting a low-cost method for dating landforms in Iceland.