## 2 Study Areas
### Grison Study Sites  
The other four study sites are located in the Swiss carton of Grison, most of them being adjacent to the Engadine valley (Figure 1b). The climate is characterized as rather dry and continental due to its inner-alpine location. The first site, Nair (Figure 1e,f), is located at the north and northeastern slopes of Piz Nair (46.51\({}^{\circ}\)N, 9.79\({}^{\circ}\)E). Lithology here consists of shales and breccias of the Mesozoic age from the Err-Nappe [56]. The site consists of several adjacent north and northeast facing rock glacier lobes. All lobes are located between 2600 and 2900 m a.s.l. and the individual lobe size ranges from 20 to 100 m in width and 50 to 200 m in length. Parts of the rock glacier have been studied previously, and the occurrence of permafrost has been observed using geophysical measurements such as seismic refraction sounding and electrical resistivity tomography (ERT) [57; 58]. The second site (Gianda Grischa, 46.49\({}^{\circ}\)N, 9.75\({}^{\circ}\)E) is located on the western slopes of Piz Julier (3380 m a.s.l.) at an elevation ranging from 2500 to 3000 m a.s.l. with lithology consisting of granites, diorites, and para-gneiss as part of the Err-Bernina nappe [59; 60]. The double-tongued rock glacier (Figure 1g,h; mark 1) is between 150 m and 400 m wide and has a length of slightly less than a kilometer facing from east to west (Figure 1f,g). Repeated kinematic and geophysical measurements have been carried out on this rock glacier [59; 60; 61]. Another inactive rock glacier [60] is located directly north of the first one (Figure 1g,h; mark 2) and has a width of 250 to 350 m and a length of 850 m facing mostly towards west and southwest. The third site, Muragl, is located in the Val Muragl (46.51\({}^{\circ}\)N, 9.93\({}^{\circ}\)E) and consists of several periglacial features: The lower part of the valley is dominated by a rock glacier located at the northern slopes of Las Sours and facing first towards north-east before turning towards west to northwest (Figure 1i,k, mark 1). The source area is located at 2800 m and the front is at about 2500 m a.s.l. with a width of 100 to 300 m and a length of about 900 m. The main rock glacier has been analyzed in several studies focusing on kinematics [29; 30; 62] and internal structure using geophysical measurements (ERT, seismic, georadar) [63; 64] as well as borehole deformation and temperature measurements [29; 65]. In the upper part of the valley, the glacier forefield hosts several smaller features (Figure 1i,k; marks 2-4), which have also been assessed in studies focusing on internal structure using geophysical measurements [66; 67; 68; 69] as well as kinematics [67; 70]. These elements are located at an elevation range from 2600 to 2800 m a.s.l and have a width of 40 to 100 m and a length of 50 to 350 m. The lithology consists mostly of granites, diorites, gneiss, and mica schists [66]. The fourth site Tellers Davains (46.54\({}^{\circ}\)N, 9.68\({}^{\circ}\)E) is located outside the upper Engadine in a side valley of the Val Surses. The main rock glacier (Figure 1l,m, mark 1) is located on the western slopes of Piz Calderas (3396 m a.s.l.) at an elevation from 2500 to 2900 m a.s.l. and has a width of 250 to 400 m and a length of 950 m. Adjacent to it in the southern direction, several smaller lobes are located at a similar elevation on the north-western slopes of Piz Cucarnegl (3050 m a.s.l.) with a width of 100 to 400 m and a length of up to 600 m (Figure 1l,m, mark 2). The lithology consists of granites and diorites of the Err-Julier nappe [71]. No studies have been carried out at this site so far, to the best of our knowledge.