Rates respond within months to changing summer air temperature, snow cover These decennial to annual changes in surface creep Many rock glaciers across the Alps show aĬommon behavior of surface creep rates with (sub-)seasonal fluctuations Preservation of ice over their entire lifetime (Barsch, 1996 Haeberli etĪnother concept is the synchronous, rapid response to warming based on Glaciers is tied to the ice supersaturation of the debris and hence to the Furthermore, the creep of millennia-old rock The ground coolingĮffect of a coarse debris mantle (Schneider et al., 2012 Wicky and Hauck,Ģ017) favors a large negative thermal offset and more resilient permafrostĬonditions even at mean annual ground temperatures close to 0 ∘C Pedersen, 1998 Humlum, 1998 Hanson and Hoelzle, 2004). The ice-rich core and the thermal decoupling from climate by the insulatingĮffect of the boulder mantle (active layer) (e.g., Haeberli et al., 2017 Īnderson et al., 2018) via the “thermal semi-conductor” effect (Harris and One concept is that rock glaciers respond in aĭelayed fashion to current warming because of the high thermal inertia of In the literature, different views on the climate sensitivity of rock Significant in the deglaciating mountains (Haeberli et al., 2017 Knight et To store significant water resources (Jones et al., 2019) and to become more Their surface kinematics is considered to beĭiagnostic of the thermal state of mountain permafrost (Delaloye et al.,Ģ018), which is otherwise not directly observable. The “visible expression of mountain permafrost” (Barsch, 1996) receiveĬonsiderable attention.
In our current warming climate (Hock et al., 2019), active rock glaciers as (Haeberli et al., 2006), and debris supply (Kenner and Magnusson, 2017). Their active phase andĭevelopment are conditioned by ice preservation, permafrost conditions Ice and ice lenses that move downslope or downvalley by creep as aĬonsequence of the deformation of ice contained in them and which are, thus,įeatures of cohesive flow” (Barsch, 1996). Perennially frozen unconsolidated material supersaturated with interstitial This work contributes to deciphering the long-term developmentĪnd the past to quasi-present climate sensitivity of rock glaciers.Īctive rock glaciers are defined as “lobate or tongue-shaped bodies of Rock glacier ideally record time since deposition on the rock glacier rootīut are stochastically altered by boulder instabilities and erosional The cosmogenic radionuclide inventories of boulders on a moving Marscha lobes that once formed persisted over millennia are less sensitive Permafrost degradation is attenuated by “thermal filtering” of theĬoarse debris boulder mantle and implies that the dynamics of the Bleis Ice at a depth which is possibly as old as its Early–Middle Holocene debris The ongoing cohesive movement of the older generations requires Phases appear to be controlled in the source area by the climate-sensitiveĪccumulation of an ice-debris mixture in proportions susceptible to rock High-elevation lobes (active since ∼2.8 ka, intermittentlyĬoexisting with oscillating Bleis Marscha cirque glacierets). Three discrete formation phases appear to be correlated to major HoloceneĬlimate shifts: Early Holocene low-elevation lobes ( ∼8.9–8.0 ka, after the Younger Dryas), Middle Holocene lobe ( ∼5.2–4.8 ka, after the Middle Holocene warm period), and Late Holocene Steps and kinematically as a sharp downslope decrease in surface movement.
Separated by time gaps expressed morphologically as over-steepened terrain Marscha is a stack of three overriding lobes whose formation phases are Surface movement exerted by topography and material properties.
We used the latter to separate the control on Marscha rock glacier (Err–Julier area, eastern Swiss Alps) with 15Ĭosmogenic nuclide exposure ages ( 10Be, 36Cl), horizontal surfaceĬreep rate quantification by correlating two orthophotos from 20,Īnd finite element modeling. We constrain the Holocene development of the active Bleis