Moraine Exposure Dates Imply Synchronous Younger Dryas Glacier Advances in the European Alps and in the Southern Alps of New Zealand

Samples taken from the top surfaces of boulders on the Lake Misery moraines at Arthur's Pass, in the Southern Alps of New Zealand, were analysed for ¹⁰Be by accelerator mass spectrometry. Exposure ages calculated with the currently accepted production rate, along with scaling corrections for sample latitude and elevation (42°50'S, 960 m), are: 9300 ± 990, 11,000 ± 1360, 11,410 ± 1030, 12,050 ± 960, and 12,410 ± 1180 years. We consider the date of 9300 years to be an outlier, not included in our mean exposure age of 11,720 ± 320 years for the Lake Misery moraines. Based on exposure ages and geomorphologic similarities, we compare the Lake Misery moraines with an Egesen moraine complex at Julier Pass in the Swiss Alps (46°30'N, 2200 m). Based on the ¹⁰Be, ²⁶Al, and ³⁶Cl exposure ages of three boulders, we calculate a mean exposure age of 11,750 ± 140 years for the outer Egesen moraine at Julier Pass. Based solely on ¹⁰Be measurements, we obtain a mean exposure age of 11,860 ± 210 years for this outer moraine. Egesen moraines in the Swiss Alps represent glacier readvance during the Younger Dryas cold reversal, based on regional correlations and on basal radiocarbon dates from bogs located up-valley of Egesen moraines. The exposure dates from Arthur's Pass and Julier Pass show synchronous glacier advances both in the Southern Alps and in the European Alps during the European Younger Dryas chronozone of Mangerud et al .     

Depositional processes and particle characteristics on fans in the Southern Alps, New Zealand

Characteristics of surface particles on four fans dominated by different depositional processes are investigated in the sedimentary ranges of the Aoraki–Mount Cook area, Southern Alps, New Zealand. Statistical testing shows that on three of the fans all indices of particle size and roundness differ significantly according to the depositional process: snow avalanches produce the largest and most angular particles, streamflows the smallest and most rounded, with debris flows in between. On the fourth fan affected by all of these depositional processes, particle size and roundness indicate that snow avalanches are presently dominant with streamflow playing a secondary role. The results also show that all indices of particle size are strongly correlated with each other and suggest that the principal (a-) or intermediate (b-) axis length may provide a satisfactory substitute for more complex indices of size. Indices of particle shape generally do not differ significantly between the fans, reflecting both the strong control exerted on particle shape by source area lithology and structure and the geologic similarity of the four basins. Changes in particle size and roundness occur with down-fan distance on the snow avalanche, debris flow, and hybrid fans but not on the streamflow fan.     

Regional relief characteristics and denudation pattern of the western Southern Alps, New Zealand

The Southern Alps of New Zealand are the topographic expression of active oblique continental convergence of the Australian and Pacific plates. Despite inferred high rates of tectonic and climatic forcing, the pattern of differential uplift and erosion remains uncertain. We use a 25-m DEM to conduct a regional-scale relief analysis of a 250-km long strip of the western Southern Alps (WSA). We present a preliminary map of regional erosion and denudation by overlaying mean basin relief, a modelled stream-power erosion index, river incision rates, historic landslide denudation rates, and landslide density. The interplay between strong tectonic and climatic forcing has led to relief production that locally attains 2 km in major catchments, with mean values of 0.65–0.68 km. Interpolation between elevations of major catchment divides indicates potential removal of l0¹–10³ km³, or a mean basin relief of 0.51–0.85 km in the larger catchments. Local relief and inferred river incision rates into bedrock are highest about 50–67% of the distance between the Alpine fault and the main divide. The mean regional relief variability is ± 0.5 km.Local relief, valley cross-sectional area, and catchment width correlate moderately with catchment area, and also reach maximum values between the range front and the divide. Hypsometric integrals show scale dependence, and together with hypsometric curves, are insufficient to clearly differentiate between glacial and fluvial dominated basins. Mean slope angle in the WSA (ψ = 30°) is lower where major longitudinal valleys and extensive ice cover occur, and may be an insensitive measure of regional relief. Modal slope angle is strikingly uniform throughout the WSA (φ = 38–40°), and may record adjustment to runoff and landsliding. Both ψ and φ show non-linear relationships with elevation, which we attribute to dominant geomorphic process domains, such as fluvial processes in low-altitude valley trains, surface runoff and frequent landsliding on montane hillslopes, “relief dampening” by glaciers, and rock fall/avalanching on steep main-divide slopes.     

Soil-stratigraphic techniques in the study of soil and landform evolution across the Southern Alps, New Zealand

The Southern Alps lie along the convergent Pacific-Indian plate boundary. Geomorphically distinct eastern, axial and western regions reflect the east-west gradient in tectonic uplift (1 to 10 mm a⁻¹) and precipitation (600 to 10,000 mm a⁻¹). The eastern region is divided into front-ange and basin-and-range subregions. Soil-sequence studies on terraces established temporal contrasts in pedogenesis within and between eastern and western regions encompassing Entisols, Inceptisols and Spodosols. On Late Pleistocene and early Holocene terraces Dystrochrepts are persistent soils in the eastern region and Aquods in the western region. These soil sequences are used in the interpretation of relative soil age, stratigraphy and erosion history in hill and mountain drainage basins of the eastern and western regions. In the subhumid to humid eastern front-range subregion, simple soil forms occur as catenary sequences, and there is little evidence of erosion following the destruction of forests in the last millenium. Mollisols are dominant in the subhumid, and Dystrochrepts in humid areas, respectively. Soil-debris mantle regoliths date from the early Holocene and are still developing on slopes. The soil pattern on mountain slopes in the humid, eastern basin-and-range subregion is a complex array of simple, eroded, composite and compound soils. This pattern has resulted from erosion following forest destruction within the last millenium. The oldest surface or buried forest soils are Dystrochrepts dating from the Late Pleistocene to early Holocene. Wind erosion of these low-fertility soils contributes to the loessial sediments in which younger soils have formed. In the western region, soil patterns and soil stratigraphy indicate continous instability with a complex pattern of highly leached, shallow Orthents and bedrock outcrops on slopes. The soils are eroded from slopes within 2 ka. These contrasts in soil development and erosion periodicity in the eastern and western regions of the Southern Alps parallel the east-west contrasts in erosion rates of ca. 1–10 mm a⁻¹.     

Tectonic geomorphology of the Triglav Lakes Valley (easternmost Southern Alps, NW Slovenia)

We present a study on the impact of litho-structural setting and neotectonic activity on meso- and macro-scale relief production in Alpine areas. The topography of the high alpine Triglav Lakes Valley, NW Slovenia, was studied by means of detailed mapping and stratigraphic study of the valley. The Triglav Lakes Valley is characterised by a generally asymmetric transverse (E–W) profile: a very steep eastern slope, a relatively flat valley and a relatively gentle western slope. On the transverse profile the valley floor is essentially flat, gently dipping towards the east. In the longitudinal cross-section, however, the valley floor is marked by sharply-defined fault blocks extending in a W–E to NW–SE direction. Additionally, the highest block (elevations  2100 m) is in the northern part of the valley, the lowest (elevations  1600 m) in the southern part of the valley. Our research shows that the Triglav Lakes Valley directly represents the topographic expression of Paleogene–Neogene thrusting and faulting, having recorded the following geomorphologic evolutionary stages: 1. an Oligocene to early Miocene W-vergent thrusting phase, with steep W-facing slopes of the eastern part of the valley directly representing the thrusting front; and 2. a Neogene-to-present strike–slip faulting in NNE–SSW direction with two bifurcating right-lateral strike–slip systems. We show that the Triglav Lakes Valley almost perfectly mimics the wedge-shaped damage zone located between these faults.     

High resolution provenancing of long travelled dust deposited on the Southern Alps, New Zealand

On 7 February 2000 an atypical orange discolouration of snowfields in the central Southern Alps, New Zealand occurred following the passage of a cold front. Analysis of snow samples identified fine orangey-brown dust mixed with much coarser grey dust. Air parcel forward trajectories from dust sources in southern and central Australia, where dust storms were reported on 4 February 2000, were computed to identify the deposits source. Geochemical analyses of the dust deposit using 26 trace elements, unaffected by regional air pollution and gravitational sorting, indicate that 20% of the dust was sourced from western New South Wales, with 45% from the eastern Eyre Peninsula of South Australia and the remaining 35% was local New Zealand dust. This provenancing approach provides a spatial resolution of long travelled dust sourcing not previously achieved.     

Temporal patterns in lacustrine stable isotopes as evidence for climate change during the late glacial in the Southern European Alps

We investigated oxygen and carbon isotopes of bulk carbonate and of benthic freshwater ostracods (Candona candida) in a sediment core of Lago Piccolo di Avigliana that was previously analyzed for pollen and loss-on-ignition, in order to reconstruct environmental changes during the late glacial and early Holocene. The depth–age relationship of the sediment core was established using 14 AMS ¹⁴C dates and the Laacher See Tephra. While stable isotopes of bulk carbonates may have been affected by detrital input and, therefore, only indirectly reflect climatic changes, isotopes measured on ostracod shells provide unambiguous evidence for major environmental changes. Oxygen isotope ratios of ostracod shells (δ¹⁸O_C) increased by ～6‰ at the onset of the Bølling (～14,650 cal BP) and were ～2‰ lower during the Younger Dryas (～12,850 to 11,650 cal BP), indicating a temporal pattern of climate changes similar to the North Atlantic region. However, in contrast to records in that region, δ¹⁸O_C gradually decreased during the early Holocene, suggesting that compared to the Younger Dryas more humid conditions occurred and that the lake received gradually increasing input of ¹⁸O-depleted groundwater or river water.     

Calving retreat and proglacial lake growth at Hooker Glacier,Southern Alps,New Zealand

Hooker Glacier in the central Southern Alps of New Zealand has undergone significant downwasting and recession (～2.14 km) during the last two centuries. High retreat rates (51 m a^?1 1986–2001, 43 m a^?1 2001–2011) have produced a large (1.22 km²) proglacial lake. We present a retreat scenario for Hooker Glacier. A retreat scenario predicts that the glacier terminus will stabilise >3 km up‐valley of the current lake outlet after 2028 when ice velocity equals calving rate.     

Relief development of a Mesozoic carbonate platform margin (Southern Alps, northern Italy)

The effect of various erosional processes on the relief development of a carbonate platform margin is documented from outcrops of the Southern Alps, northern Italy, by the occurrence of truncation surfaces and redistribution of remobilized sediments. The periplatform depositional history, with periods of intensive submarine erosion along the north-western Trento plateau margin, is recorded by various carbonate deposits ranging in age from the Early Jurassic to Late Cretaceous with numerous gaps. The first Early Jurassic period of submarine erosion is marked by truncation and extensive tectonic fracturing of lower Liassic oolitic skeletal periplatform deposits. These are overlain by pelmicritic sediments of late Hettangian to Toarcian age. The second period of submarine erosion during the late Early Jurassic resulted in almost complete truncation of the pelmicritic unit. Crinoidal to oolitic periplatform carbonate sands were subsequently deposited along the carbonate margin until the Aalenian/Bajocian. The third truncation surface was produced by partial current erosion of the crinoidal to oolitic periplatform deposits during the late Bajocian to Callovian. The fourth, and most prominent, truncation surface was produced by erosion during the Early Cretaceous cutting down from Aptian/Albian pelagic units to Toarcian periplatform deposits. The resulting submarine relief was completely buried during the late Maastrichtian by onlapping pelagic sediments. The documentation of the depositional history during the Late Mesozoic of the north-western Trento plateau pinpoints the main mechanisms responsible for the relief of the drowned carbonate platform margin. Extensional tectonic activity during differential subsidence and current-induced erosional truncation, followed by gravitational downslope mass transport and rapid pelagic burial mainly determined the morphology of the drowned carbonate platform margin.     

Urbanization and depopulation in the Alps

Demographic developments in the European Alpine region are analyzed over the period 1870-1990. The region is defined as including parts of Germany, France, Italy, Liechtenstein, Austria, Switzerland, and Slovenia. "Studies of growth, stagnation, decline, commune size, and altitude in almost 6,000 communes are presented on three colored maps.... It is apparent that two highly divergent processes are at work and, accordingly, statistical mean values reveal little of importance. Approximately one-half of Alpine Europe is undergoing general economic and demographic growth and has experienced significant increase in population since the end of the agricultural era. This development has taken place primarily in low-lying valleys and basins and in areas bordering the Alps that have good access to transport routes. Tourism is not as widespread as generally assumed and is usually characterized by a punctate pattern. Only in the western part of the Eastern Alps does tourism account for widespread population growth at higher altitudes; elsewhere the Alps have not been affected by modern development and the economy and population are declining, with some areas in danger of becoming completely abandoned. The results challenge the earlier concept of the Alps as a rural region, once populated by peasants, where tourism now plays a major role." (EXCERPT)     

Demographic trends in the Austro-German Alps

Population trends in the German and Austrian Alps between 1971 and 1981 are described. The effects of commune size, tourism, and altitude on population dynamics are considered.