Landscapes and Landforms of Austria

Inhaltsverzeichnis

1. Frontmatter

2. Introduction to the Physical Geography of Austria

   1. Frontmatter

   2. Chapter 1. Geological and Tectonic Setting of Austria

      Ralf Schuster, Kurt Stüwe

      Abstract

      The landforms of Austria are the direct consequence of a continuous interplay between tectonic and climatic forces that have built, destroyed and reshaped the surface of the most iconic mountain belt on Earth for almost 40 Million years. As such, landforms can only be understood with a thorough geological background. This paper gives an overview of the tectonic evolution, the geological build up and the landscape evolution in the Austrian territory. The tectonic evolution of the rocks forming the major tectonic units of Austria can be traced back to some 500 Million years when they were located at different ancient continents including Gondwana, Avalonia and Laurasia. In the late Palaeozoic, the basement rocks were affected by the Variscan tectonometamorphic event during amalgamation of the supercontinent Pangaea and by a Permian extensional event. The latter is responsible for and was followed by a long-lived phase of thermal subsidence triggering the deposition of the Mesozoic sedimentary pile of the Northern Calcareous Alps. The formation and later subduction of the Neotethys and Penninic oceans began in Triassic and Jurassic times, respectively. The Alpine orogen as we know it today is largely the consequence of the head-on collision between the Adriatic and European plates once subduction had terminated around 40 Ma. The geological build up of Austria includes the Alps and its northern foreland. The foreland is composed of Variscan gneisses in the Bohemian Massif, their Mesozoic cover and Cenozoic sediments in the Molasse Basin. The Alps are made up of tectonic units derived from the European and Adriatic continents and the Neotethys and Penninic oceans that are covered by some intramontane and marginal basins that are filled with Neogene sediments. The landscape evolution evolved since the Oligocene and is highly influenced by processes in the mantle. It involved the interplay of many kilometres of rock uplift and simultaneous erosion so that few rocks at the surface today can be traced back to this time. Nevertheless, low-temperature geochronology, a series of fossil relict surfaces and enigmatic deposits like the Augenstein Formation on the plateaus of the Northern Calcareous Alps testify of a stepwise formation of the landscape over the last 25 Million years. Current research shows that up to 500 m of surface uplift may have occurred in the last 5 Million years alone.

   3. Chapter 2. Geomorphological Landscape Regions of Austria

      Gerhard Karl Lieb, Christine Embleton-Hamann

      Abstract

      This chapter provides an overview of the landscapes of Austria and a general background for the individual regional chapters of Part 2 of the book. The three major landscape units of Austria are the Eastern Alps, comprising about 63% of the territory, the Alpine forelands in the north and southeast of the mountain belt (27%), and the highlands of the Bohemian Massif in the north (10%). For the designation of smaller-scale regions, the geology of these three structural units with specific attention to lithology is discussed. Based on maps of elevation, relative relief and slope inclination, four relief types are defined. The combination of geology and relief types results in ten geomorphological landscape regions. These units are finally portrayed, complemented by brief descriptions of climate and land use. The main focus of these descriptive accounts are the Quaternary and contemporary geomorphological processes and characteristic landform assemblages with references to the chapters of part 2 in which they are covered in detail.

   4. Chapter 3. The Imprint of Quaternary Processes on the Austrian Landscape

      Jürgen M. Reitner

      Abstract

      Austria has a diverse landscape as a result of the interplay of processes linked to tectonics and climate change. The final shaping occurred during the Quaternary (the last 2.58 Ma). This period is characterized by strong climatic variations on the global scale between glacial and interglacial conditions, which had different effects on the heterogeneous landscape, and its archives depending on the magnitude and duration of the climatic signal. The tectonic influence during the Quaternary is evident in instances of uplift as indicated by the Pleistocene terrace staircases of the Alpine foreland. In contrast, parts of the Vienna basin are characterized by subsidence linked to strike-slip faults. The oldest deposits are loess–palaeosol sequences (LPSs) which document the onset of loess accumulation with the occurrence of the Gauss/Matuyama palaeomagnetic reversal at the beginning of the Quaternary. The Early Pleistocene record consists of LPSs and gravel deposits with no indication of a glacier advance. Four major glaciations, namely Günz, Mindel, Riss and Würm (from oldest to youngest)—are known. These Ice Ages were characterized by a large complex of transection glaciers, i.e. an interconnected system of valley glaciers covering large sections of the Eastern Alps with glacier tongues terminating in the Alpine foreland. The three older glaciations are of Middle Pleistocene age, whereas the youngest happened during the Late Pleistocene. All four glaciations are recorded by Glacial Sequences genetically linking tongue basins with (subglacial) till, terminal moraine deposits and terraces consisting of proglacial outwash. Sediments of these glaciations differ in the degree of weathering and the characteristics of cover beds (e.g. LPSs). Based on geochronological data and the relation between type and magnitude of the global climate signal, the amount of reconstructed sediment production following correlation with major phases of global glaciation is used: Günz (MIS 16; 676–621 ka), Mindel (MIS 12; 478–424 ka), Riss (MIS 6; 191–130 ka) and (Late) Würm (MIS 2; 29–12 ka). Detailed knowledge of the Last Interglacial-Glacial cycle (130–12 ka) allows establishing models for climatically controlled sedimentary processes and for glacier expansion in the longitudinal valleys of the Eastern Alps. Overdeepened valleys and increased relief leading to different types of mass movements are also a legacy of glaciations. Evidence of Pleistocene permafrost (e.g. relict rock glaciers) as well as Holocene fluvial activity are further indications of the dynamic landscape development of the Austrian landscape during the Quaternary.

   5. Chapter 4. River and Valley Landscapes

      Gerhard Karl Lieb, Wolfgang Schöner, Christine Embleton-Hamann

      Abstract

      Rivers and valleys contribute to Austria’s proverbial beauty. Driven by climatological characteristics both elements are closely linked to each other. The section first gives a hydro-climatological characterization of Austria with special emphasis on rivers. Different runoff regimes are distinguished and can be grouped according to the influence of precipitation, evapotranspiration and storage. Snow cover and glaciers play a crucial role in hydrology due to the predominately mountainous character of Austria. Climate change will have significant consequences for hydrological processes and will be challenging for flood management in the future. Rivers have formed a complicated valley network which mirrors past tectonic processes, especially in mountainous areas. Younger geomorphological processes, in particular the Pleistocene glaciation and the glaciofluvial sedimentation combined with it, shaped the recent character of the valleys. Based on morphology and sedimentology, we provide a classification of valleys into 5 types. The sediment fills of the valleys are important for drinking water supply.

   6. Chapter 5. Karst Landscapes in Austria

      Christian Bauer, Lukas Plan

      Abstract

      The term karst refers to specific geomorphological processes and thereof resulting in characteristic landscapes. About one-fifth of Austria consists of lithologies—mainly limestone, dolomite, and marble—susceptible to dissolution (i.e. karstification). Those lithologies occur in every landscape including the complete range of altitude: Northern Calcareous Alps, Southern Calcareous Alps, Helvetic units, Central Eastern Alps, Bohemian Massif, Alpine forelands, and Neogene basins. Consequently, Austrian karst landscapes are also subjected to a suite of non-karstic geomorphological processes, resulting in a great variety of endo- and exokarst features with distinct modifications. Small-scale solution features (karren) and dolines are very common. At high altitudes, these features have been exposed to processes related to Pleistocene glaciations. Moreover, karst springs with high discharge variabilities are well-known hydrologic features. Austria hosts 18,100 caves, and some of them are amongst the longest and deepest in the world. Although the majority of the caves are of epigenetic origin, some caves are also related to hypogene speleogenesis. Imprints from human activities on the karst environment can be traced back to the Palaeolithic period. Today, human-karst interactions are of particular importance: karst aquifers provide the catchment areas for drinking water supply for several municipals and karst landscapes represent resources for tourism, recreation, and furthermore. Not least, research in karst and caves makes an important contribution to science (e.g. palaeoclimatology).

   7. Chapter 6. Geomorphic Hazards in Austria

      Sven Fuchs, Martin Wenk, Margreth Keiler

      Abstract

      Endogenic and exogenic geomorphic processes of different types and spatiotemporal dynamics can be observed within the territory of Austria. If these processes affect assets such as exposed buildings or infrastructure lines, they turn into hazards. In particular in the mountainous parts and in the Alpine foreland geomorphic hazards of different magnitude and frequency have repeatedly led to economic losses and fatalities. Together, the mountains and the Alpine foreland account for approximately 70% of the Austrian territory. Consequently, geomorphic hazards are an important issue in Austria. In the following, a brief overview of the major types of these hazards and their characteristics is given, including river and torrential flooding, gravitational mass movements, snow avalanches, hazards associated with glaciers and permafrost, as well as seismic hazards. Furthermore, information on the temporal and spatial occurrence of major event types and associated losses is provided.

   8. Chapter 7. Geoheritage, Geotourism and Landscape Protection in Austria

      Horst J. Ibetsberger, Christine Embleton-Hamann

      Abstract

      The variability of Earth’s surface materials, forms and physical processes is crucial for sustaining ecosystems and their services, as it influences fauna, flora and land use, and via land use the development of specific cultural elements of a region. Many of Austria’s nature protection areas display and interpret these abiotic attributes of nature, namely special landforms, landscapes or geological features. Nature protection under Austria’s federal system has one notable weakness, namely that the legislation and implementation of nature protection falls under the jurisdiction of its provinces. Consequently, nine individual protection laws, differing in detail and quality, exist. Only protection categories are somewhat consistent. Geoheritage in Austria is conserved in six national parks, 47 nature parks, three UNESCO Global Geoparks and one national geopark. The last category – geoparks – is unfortunately not included in Austria’s nature protection laws. Geotourism has the goal to raise the awareness of abiotic nature attributes, together with promoting a profound understanding of Earth sciences and the conservation of geodiversity. Geotourism and geoheritage are two sides of the same coin. Once a geoheritage site or park becomes a visitor magnet, its importance and value will rise, while geotourism depends on geoheritage and its protection. Geotourism must not be confused with adventure and activity tourism, in which geoheritage is occasionally used as a backdrop for activity setups. Challenges for the management of Austria’s parks and sites are manifold. On the one hand, there is the goal to increase visitor numbers, and on the other hand, any negative impact of intensified visitation on the geoheritage itself must be prevented. As always, scarcity of funds is a pervasive problem, not only for maintenance of the existing infrastructure, but more importantly for the development of best practice education in order to make every visitor a multiplier in the protection of Austria’s unique and beautiful places.