Truncated upland,
truncated highland or
bevelled upland () are the heavily
eroded remains of a
fold mountain range, often from an early period in
earth history.
[Murawski, H., Meyer, W. (2004): Geologisches Wörterbuch. Spektrum Akademischer Verlag, 11th edn., 262 pp. ][Leser, Hartmut, ed. (2005). Wörterbuch Allgemeine Geographie, 13th ed., dtv, Munich, p. 778. .] The term
Rumpfgebirge ("rump mountains") was first introduced into the literature in 1886 by Ferdinand von Richthofen.
The rumps of the former mountain ranges may be found in many lowland regions of the Earth's crust (where they form the so-called
) and especially outcrop in Central Europe through more recent
tectonics. This could result in an uplifted
peneplain, which is one type of truncated upland.
The valley structures of truncated uplands are often more irregular than in the younger fold mountains, which is due to the considerably younger tectonic processes and stronger erosion of the former that were originally often up to several thousand metres high. By contrast, their Plateau are orographically similar in shape.
Examples
In western Europe many of the
Central Upland ranges fall into the category of truncated uplands – for example the
Harz, the
Ore Mountains, the Fichtel Mountains and the
Rhenish Massif. Other ranges also date to the time of the
Variscan orogeny, including those on either side of the
Rhine, such as the
Black Forest and
Vosges and, from the
Bavarian Forest in northeast
Bavaria, through the
Bohemian Forest in the
Czech Republic to the
Bohemian Massif in
Austria and the Czech Republic, not to mention the French
Massif Central. This mountain formation took place in the Middle
Palaeozoic, during the
Devonian and
Carboniferous epochs about 350 to 250 million years ago. Already by the
Permian the Variscan mountains had been eroded into the so-called Permian peneplain and overlain by
sedimentary rock. These remains survive as
Variscan "islands" between the younger sedimentary rocks of the
Mesozoic. During the course of subsequent
earth history,
fault block tectonics followed, which characterised the present appearance of the German Central Uplands. These truncated Variscan mountains are usually strongly affected by
processes.
The erosion of the mountains exposed numerous mineral resources e.g. silver and iron ore in the Harz as well as copper (the Rammelsberg is a type locality for SEDEX deposits), or uranium in the Ore Mountains.
Even older are the Caledonian Mountains of Scotland and the rest of the Plateau and coastal mountains in Scandinavia, which were formed about 500 million years ago.
In North America the almost 3,000-kilometre-long mountain chain of the Appalachians is one of the largest areas of truncated highland in the world. It extends in widths of 200 to 300 kilometre from the southern states of the United States to the east Canadian Newfoundland, but only reaches heights of just over 2,000 metres in the south. Many of coal, mineral oil and iron ore, as well as fertile make the range and its surrounding area into one of the richest regions of America.
The Urals between eastern Europe and Siberia have a similar importance in terms of mining and the economy; and the extent of these mountains in Russia, which are up to 1,900 metres high, is similar to that of the Appalachians.
Literature
