Tracing the path of ice in northern Namibia: mapping the remnants of long-gone glaciers with photogrammetry in unprecedented resolution

The glacial features of the Late Palaeozoic Ice Age (LPIA) in northern Namibia have been disproportionately understudied compared to the southern part of the country. Although some initial insights were gained from mid-20th century expeditions, there has been a significant lack of detailed scientific investigations in the area since then (e.g. Martin & Schalk, 1959). Recent studies have begun to address this gap and aim to reinvigorate research in the region (Dietrich et al., 2021; Fedorchuk et al., 2023, Rosa et al., 2023). 

By utilizing large-scale aerial and close-range photogrammetry, we have been able to meticulously map the beds of vanished glaciers at an unprecedented resolution. Quantitative analyses of macroscale ice flow features, including over 16 000 measurements of striae and crescentic fractures in a single area, enable us to determine the directions of ice movement and allow us to correlate them with the suggested local flow direction of a large-scale paleo-fjord network (Dietrich et al., 2021). Analysing selected areas of potential subglacial bedrock failure on high-resolution outcrop photos and detailed 3D models allows us to determine the influence of meltwater and the overlying glacier on erosional features such as crescentic fractures and joint-bounded scars.

Our findings raise important questions regarding the conditions beneath the glacier, including the phases of glaciation evident in the exposed bedrock, subglacial bedrock failure, and the extent and influence of meltwater activity.

Recent efforts to focus scientific attention on the relatively underexplored northern regions of Namibia present a promising opportunity to enhance the existing understanding of glaciations during the LPIA on Gondwana and to utilize these findings to gain better insights into the development of subsequent glaciations.