The peculiar case of glacier-transported glass bottles at Piz Murtèl, Swiss Alps

Glacier ice flow not only transports eroded rock material, but can also mobilize remnants of previous touristic activities, linking physical environment with human exploitation of mountains. Here, we investigate the transport and deposition of bottles and cans on a small, rapidly shrinking glacier in the Southeastern Swiss Alps. Object positions were documented using the global positioning system (GPS), and for several items, age estimates from literature and manufacturers suggest production dates between about 1900 and 1980. Field observations were combined with glaciological data and the results from a higherorder iceflow model to reconstruct their likely origin, transport pathways, and deposition period. The results indicate that the objects originated from the summit area of Piz Murtèl and were transported downslope by ice flow or by sliding over the surface, leading to the deposition of several hundred objects along the former glacier margin. We therefore conclude that bottles and cans were discarded near the summit of Piz Murtèl between more than a century and 50 years ago, and were then transported to form a morainelike shape. These findings demonstrate that glacierscale reconstructions of surface and englacial debris transport are feasible and highlight the role of glaciers as longterm archives of human activity in alpine environments.