Sudetes

Timber line

The higher mountains of the Sudetes lie above the timber line which is made up of Norway spruce.^[5][9] Spruces in wind-exposed areas display features such as flag tree disposition of branches, tilted stems and elongated stem cross sections.^[10] Forest-free areas above the timber line have increased historically by deforestation^[8] yet lowering of the timber line by human activity is minimal.^[9] Areas above the timber line appear discontinuously as "islands" in the Sudetes.^[5] In the Giant Mountains the timber line lies at c. 1230 m a.s.l. while to the southeast in the Hrubý Jeseník mountains it lie at c. 1310 m a.s.l.^[5] Part of the Hrubý Jeseník mountains have been above the timber line for no less than 5000 years.^[5] Mountains rise considerably above the timber line, at most 400 m, a characteristic that sets the Sudetes apart from other Mittelgebirge of Central Europe.^[1]

Bedrock

The igneous and metamorphic rocks of the Sudetes originated during the Variscan orogeny and its aftermath.^[12] The Sudetes are the northeasternmost accessible part of Variscan orogen as in the North European Plain the orogen is buried beneath sediments.^[13] Plate tectonic movements during the Variscan orogeny assembled together four major and two to three lesser tectonostratigraphic terranes.^[14][C] The assemblage of the terranes ought to have involved the closure of at least two ocean basins containing oceanic crust and marine sediments.^[15] This is reflected in the ophiolites, MORB-basalts, blueschists and eclogites that occur in-between terranes.^[14] Various terranes of the Sudetes are likely extensions of the Armorican terrane while other terranes may be the fringes of the ancient Baltica continent.^[13] One possibility for the amalgamation of terranes in the Sudetes is that the Góry Sowie-Kłodzko terrane collided with the Orlica-Śnieżnik terrane causing the closure of a small oceanic basin. This event led to obduction of the Central Sudetic ophiolite in the Devonian period. In the Early Carboniferous the joint Góry Sowie-Kłodzko-Orlica-Śnieżnik terrane collided with the Brunovistulian terrane. This last terrane was part of the Old Red Continent and could correspond either to Baltica or the eastern tip of the narrow Avalonia terrane. Also by the Early Carboniferous the Saxothuringian terrane collided with the Góry Sowie-Kłodzko-Orlica-Śnieżnik terrane closing the Rheic Ocean.^[16]

Once the main phase of deformation of the orogeny was over basins that had formed in-between metamorphic rock massifs were filled by sedimentary rock in the Devonian and Carboniferous periods.^[15] During and after sedimentation large granitic plutons intruded the crust. Viewed in a map today these plutons make up about 15% the Sudetes.^[12][15] Granites are of S-type.^[13] The granites and grantic-gneisses of Izera in the west Sudetes are disassociated from orogeny and thought to have formed during rifting along a passive continental margin.^[17][D] The Karkonosze Granite, also in the west Sudetes, have been dated to have formed c. 318 million years ago at the beginning of the Variscan orogeny.^[18] The Karkonosze Granite is intruded by somewhat younger lamprophyre dykes.^[18]

A NW-SE to WNW-ESE oriented strike-slip fault —the Intra-Sudetic fault— runs through the length of the Sudetes.^[15] The Intra-Sudetic fault is parallel with the Upper Elbe fault and Middle Oder fault.^[13] Other main faults at the sudetes are also NW-SE oriented, dextral and of strike slip type. These include the Tłumaczów-Sienna Fault and the Marginal Sudetic Fault.^[19]

Volcanism and thermal waters

There are remnants of lava flows and volcanic plugs in the Sudetes.^[20] The volcanic rocks making up these outcrops are of mafic chemistry and include basanite and represent episodes of volcanism in the Oligocene and Miocene periods.^[20][E] Volcanism affected not only the Sudetes but also parts of the Sudetic foreland being part of a SW-NE oriented Bohemo-Silesian Belt of volcanic rocks.^[20] Mantle xenoliths have been recovered from the lavas of a volcano at Ještěd-Kozákov Ridge in the Czech western Sudetes.^[21] These pyroxenite xenoliths arrived to surface from approximate depths of 35, 70 and 73 km and indicate a complex history for the mantle beneath the Sudetes.^[21]

There are thermal springs in the Sudetes with measured temperatures of 29 to 44 °C. Drilling has revealed the existence of waters at 87 °C at depths of 2000 m. These modern waters are believed to be associated to the Late Cenozoic volcanism in Central Europe.^[22]

Uplift and landforms

The Sudetes forms the NE border of the Bohemian Massif.^[13] In detail the Sudetes is made up of a series of massifs that are rectangular and rhomboid in plan view.^[23] These mountains corresponds to horsts and domes separated by basins, including grabens.^[24] The mountains took their present form after the Late Mesozoic retreat of the seas from the area which left the Sudetes subject to denudation for at least 65 million years.^[23] This meant that during the Late Cretaceous and Early Cenozoic 8 to 4 km of rock was eroded from the top of what is now the Sudetes.^[25] Concurrently with the Cenozoic denudation the climate cooled due to the northward drift of Europe. The collision between Africa and Europe has resulted in the deformation and uplift of the Sudetes.^[23] As such the uplift is related to the contemporary rise of the Alps and Carpathians.^[23][11][F] The acceleration of uplift of the Sudetes occurred during the Middle Miocene because of the Bohemian Massif's growth.^[26] Uplift was accomplished by the creation or reactivation of numerous faults leading to a reshaping of the relief by renewed erosion.^[12] Various "hanging valleys" attest to this uplift.^[11] Block tectonics has uplifted or sunken crustal blocks. While the Late Cenozoic uplift has uplifted the Sudetes as a whole some grabens precede this uplift.^[19]

Weathering during the Cenozoic led to the formation of an etchplain in parts of Sudetes. While this etchplain has been eroded various landforms and weathering mantles have been suggested to attest its former existence.^[12] At present the mountain range shows a remarkable diversity of landforms.^[23] Some of the landforms present are escarpments, inselbergs, bornhardts, granitic domes, tors, flared slopes and weathering pits.^[12] Various escarpments have originated from faults and may reach heights of up to 500 m.^[11] To the northeast the Sudetes is separated from the Sudetic foreland by a sharp mountain front made up of an escarpment linked to the Sudetic Marginal Fault.^[27] Near Kaczawa this escarpment reaches 80 to 120 m in height. The relative influence of Pliocene-Quaternary tectonic movements and erosion in shaping the mountain landscape may vary along the northern front of the Sudetes.^[27]

During the Quaternary glaciations the Giant Mountains was the most glaciated part of the Sudetes. Evidence of this are its glacial cirques and the glacial valleys that develop next to it.^[1] The precise timing of the glaciations in the Sudetes is poorly constrained.^[1] Parts of the Sudetes remained free from glacier ice developing permafrost soils and periglacial landforms such as rock glaciers, nivation hollows, patterned ground, blockfields, solifluction landforms, blockstreams, tors and cryoplanation terraces.^[9] The occurrence or not of these periglacial landforms depends on altitude, the steepness and direction of slopes and the underlying rock type.^[9]

Mass wasting

Other than debris flows there is little contemporary mass wasting in the mountains.^[1] Avalanches are common in the Sudetes.^[1]

Sudetes and "Sudetenland"

After World War I, the name Sudetenland came into use to describe areas of the First Czechoslovak Republic with large ethnic German populations. In 1918, the short-lived rump state of German-Austria proclaimed a Province of the Sudetenland in northern Moravia and Austrian Silesia around the city of Opava (Troppau).

The term was used in a wider sense when on 1 October 1933 Konrad Henlein founded the Sudeten German Party and in Nazi German parlance Sudetendeutsche (Sudeten Germans) referred to all autochthonous ethnic Germans in Czechoslovakia. They were heavily clustered in the entire mountainous periphery of Czechoslovakia—not only in the former Moravian Provinz Sudetenland but also along the northwestern Bohemian borderlands with German Lower Silesia, Saxony and Bavaria, in an area formerly called German Bohemia. In total, the German minority population of interwar Czechoslovakia numbered around 20% of the total national population.

Sparking the Sudeten Crisis, Adolf Hitler got his future enemies Britain and France to concede the Sudetenland with most of the Czechoslovak border fortifications in the 1938 Munich Agreement, leaving the remainder of Czechoslovakia shorn of its natural borders and buffer zone, finally occupied by Germany in March 1939. After being annexed by Nazi Germany, much of the region was redesignated as the Reichsgau Sudetenland.

After World War II, most of the previous population of the Sudetes was forcibly expelled on the basis of the Potsdam Agreement and the Beneš decrees, and the region was resettled by new Polish and Czechoslovak citizens. A considerable proportion of the Czechoslovak populace thereafter strongly objected to the use of the term Sudety. In the Czech Republic the designation Krkonošsko-jesenická subprovincie is used in academic context and usually only the discrete Czech names for the individual mountain ranges (e.g. Giant Mountains) appear, as under Subdivisions above.

Notable towns

Towns in this area with more than 10,000 inhabitants include: