Permafrost, Phillips, Springman & Arenson (eds) © 2003 Swets & Zeitlinger, Lisse, ISBN 90 5809 582 7

Lateglacial and Holocene evolution of and permafrost in the Val Muragl, Upper , Swiss

M. Maisch, W. Haeberli, R. Frauenfelder, A. Kääb Glaciology and Geomorphodynamics Group, Geography Department, University of Zurich, C. Rothenbühler Academia Engiadina, , Switzerland

ABSTRACT: Spectacular landforms associated with permafrost creep and fluctuations characterize the Val Muragl, one of the most frequently visited high-mountain valleys and tourist attractions in the St. Moritz area, Upper Engadin, eastern . Combined consideration of glaciers and permafrost enhances the possibili- ties of understanding the landscape evolution in this area. The Val Muragl is able to constitute a large and easily accessible “geotope-site” illustrating phenomena and processes of Lateglacial, Holocene and present-day time scales. The scientific vision is based on a variety of methodological approaches such as GIS-based geomorpho- logical mapping, reconstruction of Lateglacial and Holocene palaeoglaciers, field mapping and spatial modelling of permafrost occurrences, photogrammetric analyses, relative age dating using the Schmidt–Hammer technique, geophysical soundings, drilling and borehole investigations. The landscape evolution starts from a situation with a cold or polythermal accumulation area, covering most of the topography during full Ice-Age conditions, and leads to Lateglacial retreat stages of polythermal valley glaciers surrounded by permafrost. The Holocene situa- tion displays repeated but spatially limited glacier advances accompanied by the development of large sediment bodies partially subjected to permafrost creep and the present-day situation is characterized by ongoing vanish- ing of the remaining surface ice as well as by complex patterns of de- and aggrading periglacial permafrost.

1 INTRODUCTION of a 20,000-year landscape evolution with quite dra- matic changes. As a consequence, Val Muragl has an Present-day landforms in cold mountain areas are important potential to be declared a protected site of strongly influenced by their development since full high value for geoscience and landscape or a so-called Ice-Age conditions (Florineth 1998) via Lateglacial ice “geotope”. The following briefly outlines the main disappearance to Holocene ice fluctuations and 20th aspects to be considered in this context, i.e. the scien- century warming trends (Maisch 2001). Under condi- tific background and the evaluation of the interest tions of a climate which is transitional between from the side of the public – a true transdisciplinary wet-maritime conditions at humid margins of coastal task of glacier and permafrost research. mountains and dry continental regimes found in many mountain chains at greater distance to oceanic sources, annual precipitation is generally around 1000 mm 2 GEOMORPHOLOGY OF VAL MURAGL at timberline and polythermal glaciers coexist with periglacial permafrost in close neighbourhood (Haeberli Geomorphology, as a specialized and meanwhile 1983, Kneisel 1999, Kneisel et al. 2000). Thorough highly computerized discipline of earth science and in understanding of landscape evolution must, therefore, combination with the topographic, geological, hydro- be based on a combined consideration of both types of logical and glaciological background provides one of perennial ice occurrences and their various but still the most important “information layers” for multidis- hardly investigated interactions through time. ciplinary landscape analysis, its interpretation and The Val Muragl in the Upper Engadin, eastern visualisation (Fig. 1). Swiss Alps, has not only been a focus of correspon- In high-alpine environments such as the Bernina ding research for years now but also represents one of region and its adjacent valleys, most geomorphic the major attractions within the spectacular and processes are evidently dynamic; on the “macro-”, world-famous tourist region around St. Moritz and “meso-” and “micro-scale” level, they are strongly . This means that a great number of hikers linked to numerous other natural phenomena such as visit an area with extraordinarily well developed permafrost distribution, soil development and vegeta- “text-book” examples of typical high-mountain land- tion cover (cf. glaciological map of Julier-Bernina; NFP forms, enabling a deep understanding of glacial as 31 1998; cf. Haeberli et al. 1999). Geomorphological well as periglacial processes and a fascinating vision aspects serve also as modern guidelines for specific

717 Figure 1. 3D-view of the Bernina region with Val Muragl in the center. Satellite imagery ©ESA/Eurimage 1990–1994. Image processing by Dr. Urs Frei, Remote Sensing Laborato- ries RSL, Geography Department. University of Zurich. public and tourism-related educational concepts of landscape didactics (WWF Switzerland & Natf. Gesel- lschaft Engadin, 1998: “Climate trail Pontresina/ Muragl”; Maisch et al. 1999: “Glacierforefield trail Morteratsch”). Figure 2. Section (appr. 5 3 km) of the geomorpholog- The geomorphology of the Val Muragl and the adja- ical map of Val Muragl and Val Champagna (Rothenbühler cent areas of Val Champagna, Val Languard and Val 2000, simplified legend in German). Roseg, was recently mapped, accomplished with a new GIS-based approach, described and analyzed (Rothenbühler 2000) as a mosaic-like part of an extended mapping project on the geomorphology of the entire northern Swiss part of the Bernina massif (Maggetti 1994, Vogel 1995, Castelli 2000, Koch in prep.). A small section of the geomorphologic cartog- raphy of the inner Val Muragl is illustrated in Figure 2. The mapping procedure applied here followed the “GMK 25-concept” (Leser & Stäblein 1975, Schoeneich 1993, cf. also Kneisel et al. 1998). The concept divides the landforms and the associated processes (in a simplified way) into different process units (glacial, periglacial, fluvial, gravitational, denuda- tional, biotic/organic and anthropogenic) according to Figure 3. Oblique low angle view of the upper part of their predominance represented by a standardized Val Muragl with the most pronounced landforms indicated colour system. In the order of significance, gravita- (Photography: Chr. Rothenbühler, 2000). tional (rock falls from headwalls at high altitudes), denudational (valley slopes in general without clearly developed landforms), glacial (morainic ridges of debris flow channels depositing debris fans at the foot- lateglacial or holocene age, glacier forefields, ice- zone of the slopes especially in the Val Champagna. marginal terraces) and periglacial zones (rockglaciers, protalus ramparts) are the most frequent geomorpho- 3 FULL ICE AGE CONDITIONS logic units found in Val Muragl with respect to their spatial distribution and importance in recent geomor- During maximum glaciation (around 20 ka BP). Val phologic activity (Fig. 3). Muragl and the entire region of the Upper Engadin Fluvial processes (debris flows and alluvial fans) are was part of a major centre and dome within the accu- mirrored by a large number of erosional scars and mulation zone of the Ice-Age glaciers, receiving their

718 a) Longitudinal valley profile precipitation predominantly from mediterranean actual glacier size 4049 m sources in the south and flowing radially out to vari- Val Champagna Val Muragl ous directions (Florineth 1998). Only ridges above 1850 Val Languard Berninapass about 2,600 to 3,000 m a.s.l. stuck out of the firn Margun 1850 Punt Muragl Pontre- surface which may have been cold with mean annual sina MorteratschRoseg firn temperatures around 15 to 20°C (Blatter & Cinuos-chel Samedan Haeberli 1984). Deep penetration of subglacial per- mafrost, especially on valley slopes, and of continu- b)Time/space-diagram of the glacier front position ous mountain permafrost on ice-free ridges and (Roseg/Tschierva and ) glaciers summits must be assumed. However, polishing and glacier advance today period 1850of striations of high-altitude bedrock (on the rounded Holocene advance real distance periods not to scale crest between Val Muragl and Val Champagna, for stadial of of glacier as small

Pontresina as in 1850 Holocene instance) indicates that temperate basal conditions (ca. 11’000 y BP) 10000 y BP stadial of must have existed in the glaciers during earlier and Samedan stadial of (ca. 13’000 y BP) E

? M

I

Cinuos-che TIMET later stages of ice build-up and vanishing. This leaves (ca. 14’000 y BP) important questions concerning the timing, duration ? glacier front retreat ? and maximum depth of subglacial permafrost forma- position unknown

Lateglacial period tion open and indicates high complexity of spatio- LGM last glacial maximum 20000 y BP temporal permafrost development at depth. SPACESPACE end series glacier advance periods glacier front position ("stadials", cool phases) estimated ages 14C-years BP glacier retreat periods y BP (before present, uncalibrated) ("interstadials", warm phases) reconstructed variations of 4 LATEGLACIAL EVOLUTION villages the glacier front position

The Lateglacial decay of surface ice (20,000-10,000 y Figure 4. Generalized system of late-würmian glacier retreat, adapted for the Bernina region. a) longitudinal valley BP, uncalibr.) in and around the Bernina region profile stretching from the stadial of Cinuos-chel up to the formed noticeable morainic systems near Cinuos-chel recent glaciers (in black) and b) Time/space diagram of the (Clavadel-stadial), Samedan (Daun-stadial) and glacier front positions reconstructed by moraine correlation. Pontresina (Egesen-stadial; Beeler 1977, Maisch 1981, Suter 1981, Suter & Gamper-Schollenberger 1982; Maisch 1992, 2000). Equivalent morainic series, cor- N related by ELA-depressions and moraine geomor- 0 1 2 3 km phology (Fig. 4), can also be identified in adjacent Va 785 En / l Champ Piz Uter 156 valleys of the Upper Engadin (Ivy-Ochs et al. 1996, agn ELA 2520 m a ELA 2680 m Ohlendorf 1998). Muottas Muragl According to Gamper & Suter (1982) and "Margun" ELA 2900 m "Punt Muragl" Val Muragl Rothenbühler (2000), two main morainic series (and Piz Vadret ELA 2560 m ELA 2770 m related subseries) can be mapped and used for Flaz ELA 2650 m glacier in 1850 palaeoglaciological reconstructions of lateglacial Piz Muragl retreat (or perhaps better “readvance”) stages in the Piz Languard Val Lang Val Muragl (Fig. 5). uard Calculations with the AAR-method (Accumulation ELA 2840 m

ELA 2630 m glacier in 1850 Area Ratio of 0.67; cf. Gross et al. 1977) and inter- mountain peaks ELA 2720 m 3000 contour lines of glacier pretation of corresponding ELA-depressions as com- 30 glacier positions surface topography (interval 100 m) Piz Albris pared to the “1850-situation”, taken as reference for "Punt Muragl" ELA (reconstructed, AAR 0.67) "Margun" 795 148 glaciological and chronological parallelism, can pro- rivers "1850-Little Ice Age" duce surprisingly variable results. Figure 5. Reconstruction of the the ice surface topography In Figure 6 the ELA-variations of the “Punt and the ELA (equilibrium line altitude) during the local gla- Muragl”, the “Margun” and “1850-situation” (zero- cier front positions of “Punt Muragl”, “Margun” and “1850” line) and the “present-day glaciation” are displayed, in the valleys of Champagna, Muragl and Languard. reconstructed manually on topographic maps (scale 1:25‚000) and edited by a group of 67 students. The wide scattering of ELA-values illustrates the highly “rule of thumb-approach” (Gross et al. 1977). Given variable effect of individual interpretation and the large variability by the method and taken the exist- palaeoglaciological reconstruction as well as of the ing ranges of ELA-depression values for the inherent uncertainities of the AAR-method itself, Lateglacial stadials, there is no possibility for a clear which was found and set up as a simple empirical and and strict decision on the question, whether the

719 500 Chur Val Muragl glacier size Val Champa Samedan area loss ELA depression glacier since 1850 gna surface 6 area glacier surface 400 in 1850 area today villages Punt Muragl St. Moritz Pontresina lakes mean: 247 m – 43 Val Langua rd 300 + σ Engadin 3 − σ Upper Val Roseg 200 2 V Morteratsch 4 Berninapass +σ al Fex 1 Val Fedoz − σ 100 5 Margun mean: 147 m – 36 0 ELA 1850 (level of reference) ELA position [m] selected glaciers glacier mean: -153 m – 30 V present day 1 Roseg surface area al Poschiavo 2 Tschierva 5 2 3 Morteratsch 1 -100 0.5 4 Cambrena km2 + σ 5 Pal 0 5 km 10 − σ 6 Muragl N -200 ELA rise Figure 7. Regional map of glaciers and glacier retreat -300 since 1850 in the Bernina region (after Maisch 1992). 1 10 20 30 40 50 60 67 number of students [n] Figure 6. Variability of individual ELA-measurements precipitation at 2000 m a.s.l.), the Bernina region (total sample n 67) on the glacier front positions of “Punt (highest peak is Piz Bernina 4049 m) is one of the Muragl”, “Margun”, “1850” and “present day”. most densely glacierized mountain ranges in the Eastern Swiss Alps (Fig. 7). situation “Punt Muragl” has to be interpreted as a Glacier size and regional glacier distribution are (may be younger) phase of the “Samedan-stadial” clearly connected with mountain topography, thus (Daun; Suter & Gamper 1982) or as equivalent to influencing the altitude and extension of the accumu- the “Pontresina-stadial” (Egesen, Younger Dryas; lation zones of the existing glaciers (Maisch 1992). Rothenbühler 2000). The age difference between This combination produces a much stronger glacia- these two correlation possibilities would be at least tion in the north facing valleys of the Bernina massif 2,000 years. During these lateglacial readvances of (Roseg, Morteratsch, Fex, Fedoz) which are much small valley glaciers filling parts of Val Muragl, mean more sheltered against radiation input from sunlight. annual air temperatures were probably lower than On the other hand glacier size tends to decrease today by at least 3°C and local limits of discontinuous towards the outer edges of the Bernina mountains mountain-permafrost occurrence were correspond- which offer only lower elevated cirque headwalls and ingly depressed by some 500 m or more (Frauenfelder provide less favourable conditions for glacier feeding et al. 2001). With mean annual air temperatures (Val Muragl, Val Languard). This decrease in glacier around 5 to 10°C near the ELA, the lateglacial size is accompanied by an increase in the relative glaciers can be assumed to have been polythermal, importance of periglacial debris and discontinuous with a temperate accumulation area (meltwater perco- permafrost. In fact, conspicuous bodies of debris lation and refreezing) and partially cold ablation areas accumulated in the form of periglacial debris cones (Frauenfelder et al. 2000). The exceptionally well- and in the forefields of the remaining cirque glaciers preserved orographic right-lateral in the at the head of the valleys. In Val Muragl area, the Val Muragl exhibit structures which indicate cohesive periglacial debris cones started to creep and – over the deformation under conditions of ice-rich permafrost – millennia involved since deglaciation – developed into a fact which appears plausible with the inferred ther- one of the most spectacular rock glaciers in the Alps. mal structure of the glacier tongues and ice margins Relative age dating with the Schmidthammer-method frozen to their beds. clearly documents that the coarse blocks at the surface of this rock glacier creeping at characteristic rates of several decimeters per year (Kääb & Vollmer 2001) 5 HOLOCENE AND LITTLE ICE AGE is increasing along flowlines from top towards the front. Relative ages remain intermediate between recent Since the onset of the Holocene, climate, glaciers and ages of blocks freshly deposited at the foot of the permafrost in the Alps are commonly assumed to have headwall and ages of rocks exposed in the moraines of varied within the extremes of conditions of the Little lateglacial age. The polythermal structure of the his- Ice Age (“1850”) and today, respectively. Despite the torical/holocene and present-day cirque glacier leads to relative dryness of regional climate (appr. 900 mm a patchy distribution of permafrost occurrence in the

720 highly elevated sediment bed of the forefield as a reflec- to be protected as an information site on high-mountain tion of highly complex glacier/permafrost-interactions glaciers and permafrost. An integrated inventory, (Kneisel et al. 2000). Part of this complexity is also the modelling and monitoring study is now underway as direct displacement of debris through rock fall, debris part of the project GISALP within the National flow, avalanche transporation or permafrost creep to Research Programme 48 “Landscapes and Habitats of the glacier forefield during times of reduced glacier the Alps” (SNF 2001). area (Maisch et al. 1999).

6 RECENT WARMING REFERENCES Arenson, L.U., Almasi, N. & Springman, S.M. 2003a. The ice-decay since 1850 reveals a surprising variety Shearing response of ice-rich rock glacier material.This in individual glacier behaviour. In general, a signifi- volume. cant inverse correlation of relative area loss with for- Arenson, L.U., Hawkins, P.G. & Springman, S.M. 2003b. mer glacier size can be observed (Gross 1987, Maisch Pressuremeter tests within an active rock glacier in the et al. 2000). The group of small and tiny glaciers, like Swiss Alps. This volume. Barsch, D. 1973. Refraktionsseismische Bestimmung der they are overrepresented in the Val Muragl area, tend Obergrenze des gefrorenen Schuttkörpers in verschiede- to disappear completely. In fact, only smallest and nen Blockgletschern Graubündens. Zeitschrift für Glet- slightly cold ice bodies (“glacierets”) remain today in scherkunde und Glazialgeologie 9(1–2): 143–167. the Val Muragl. Due to continuous glacier recession Beeler, F. 1977. Geomorphologische Untersuchungen am and in a complementary way large areas covered with Spät- und Postglazial im Schweizerischen Nationalpark unstable material get exposed, building a pioneer like, und im Berninapassgebiet (Südrätische Alpen). Ergeb- nisse der wissenschaftlichen Untersuchungen im geomorphic fresh and dynamic zone, usually called Schweizerischen Nationalpark, XV, PhD.-thesis, “glacier forefield”. Some of the forefields getting ice- Geography Dept., University of Zurich. free by glacier recession are exposed newly (or again) Blatter, H. & Haeberli, W. 1984. Modelling temperature dis- to climate conditions favourable for permafrost occur- tribution in Alpine glaciers. Annals of Glaciology 5: rence (NFP 31 1998, Kneisel 1998, 1999, Kneisel et al. 18–22. 2000). A long tradition of rock-glacier investigations Castelli, S. 2000. Glazialmorphologische Kartierungen im Gebiet zwischen Julierpass und . Diploma (Salomon 1929, Domaradzki 1951, Barsch 1973, thesis, Geography Dept., University of Zurich. Haeberli 1992, Frauenfelder & Kääb 2000, Kääb Domaradzki, J. 1951. Blockströme im Kanton Graubünden. & Vollmer 2000, Arenson et al. 2003ab, Maurer et al. Ergebnisse der wissenschaftlichen Untersuchungen des 2003, Vonder Mühll et al. 2003) provides more and schweizerischen Nationalparks III(24): 177–235. more detail on the nearby rock glacier (mentioned Florineth, D. 1998. Surface geometry of the Last Glacial above), the frontal and marginal parts which are now Maximum (LGM) in the southeastern Swiss Alps (Graubünden) and its paleoclimatolological signifi- close to the local permafrost limit and contain thin cance. Eiszeitalter und Gegenwart 48: 23–37. permafrost at pressure melting temperature. Such Frauenfelder, R. & Kääb, A. 2000. Towards a paleoclimatic signs of permafrost degradation contrast with possible model of rock glacier formation in the Swiss Alps. local aggradation of permafrost in parts of the newly Annals of Glaciology 31: 281–286. exposed glacier forefield. Frauenfelder, R., Haeberli, W., Hoelzle, M. & Maisch, M. 2001. Using relict rockglaciers in GIS-based modelling to reconstruct Younger Dryas permafrost distribution 7 PERSPECTIVES AND RECOMMENDATIONS patterns in the Err-Julier area, Swiss Alps. Norsk Geografisk Tidsskrift 55: 195–202. Gamper-Schollenberger, B. & Suter, J. 1982. Gletsch- The well-preserved remains of earlier glaciations and erausdehnungen im Oberengadin (map). In M. Maisch the striking periglacial creep phenomena in the Val & J. Suter (eds), Exkursionsführer Teil A: Ostschweiz. Muragl are highly representative landforms reflecting Hauptversammlung der Deutschen Quartärvereinigung climate-change effects on glaciers and permafrost in (DEUQUA) in Zürich, 1982. Physische Geographie dryer parts of the Alps and other cold mountain chains Vol. 6, Zurich. Gross, G. 1987. Der Flächenverlust der Gletscher in Österre- of the world. Their combined existence within an eas- ich 1850–1920–1969. Zeitschr. für Gletscherkunde und ily accessible catchment and especially the rich scien- Glazialgeologie, 2: 131–141. tific documentation concerning their evolution and Gross, G., Kerschner, H. & Patzelt, G. 1977. Methodische mutual interaction is quite unique. Beyond such geo- Untersuchungen über die Schneegrenze in alpinen scientific aspects, the touristic potential and the sig- Gletschergebieten. Zeitschr. für Gletscherkunde und nificance of the phenomena to be seen and understood Glazialgeologie XII(2): 223–251. Haeberli, W. 1983. Permafrost-glacier relationships in the in the area described constitute a high value to society. Swiss Alps today and in the past. Proceedings of the The Val Muragl with its moraines and rock glaciers, Fourth International Conference on Permafrost: therefore, can be recommended to become a “geotope” 415–420.

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