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14-660: It is situated in the Hegau region, about 5 km northwest of Lake Constance , 13 km north of Radolfzell and 25 km northwest of Konstanz . Stockach includes the central city and 10 villages: The Counts of Nellenburg founded Stockach in the 13th century, the town receiving town privileges in 1283. In 1401 to the Landgraviate of Nellenburg owned the towns of Engen , Tengen , Radolfzell , Stockach, 125 villages, 9 abbeys and 4 mailing stations. The Counts of Nellenburg became extinct in 1422 and their estates were acquired by

28-461: A thick sequence of potassium-rich trachyandesite lavas that are significantly more resistant to erosion than the Mesozoic siltstone and other rock in which the valley was cut. Thus, subsequent differential erosion left these volcanic rocks as a sinuous ridge, which now stands well above landscape underlain by more deeply eroded Mesozoic rocks. Another example is Table Mountain , Cape Town , where

42-472: Is a stub . You can help Misplaced Pages by expanding it . This article about a regional geological feature is a stub . You can help Misplaced Pages by expanding it . Inverted relief Inverted relief , inverted topography , or topographic inversion refers to landscape features that have reversed their elevation relative to other features. It most often occurs when low areas of a landscape become filled with lava or sediment that hardens into material that

56-557: Is more resistant to erosion than the material that surrounds it. Differential erosion then removes the less resistant surrounding material, leaving behind the younger resistant material, which may then appear as a ridge where previously there was a valley. Terms such as "inverted valley" or "inverted channel" are used to describe such features. Inverted relief has been observed on the surfaces of other planets as well as on Earth. For example, well-documented inverted topographies have been discovered on Mars . Several processes can cause

70-546: Is the Hohentwiel , on top of which lie the ruins of a fortress of the same name. The Hohentwiel is located next to the industrial city of Singen . It is the southernmost of the Hegau volcanoes. To the north of it, there are nine other extinct volcanoes (see list below). 47°47′42″N 8°45′00″E  /  47.795°N 8.750°E  / 47.795; 8.750  ( Hohenstoffeln ) This Konstanz location article

84-692: The French First Republic and the Habsburg monarchy in 1799 and 1800 . In 1810 Stockach finally fell to the Grand Duchy of Baden . Stockach is twinned with: Hegau Hegau either refers to a region of the Duchy of Swabia or to only that part of said region which is presently located in the country of Germany . It is known for its extinct, partly eroded volcanoes, most of which are crowned with ruins of medieval fortresses. Historically, Hegau

98-797: The House of Habsburg in 1465; hence Stockach was a part of Further Austria until 1805. In the Swabian War of 1499 the troops of the Three Leagues besieged the town but failed to capture it. During the War of the Spanish Succession , Elector Maximilian II Emanuel of Bavaria set fire to Stockach. During the French Revolutionary Wars of the Second Coalition two battles were fought here between

112-561: The Miocene epoch , from about 14 Ma ago to around 6 Ma ago. Much later, during the Riss glaciation ( Pleistocene epoch), about 150 ka ago, the Hegau region was covered by large glaciers, which over time eroded the softer rocks around the harder basaltic rocks of the former volcanic pipes (an example of an inverted relief ). After the melting of the ice age glaciers, the landscape received its typical, modern-day appearance. In conjunction with

126-479: The floor of a depression to become more resistant to erosion than its surrounding slopes and uplands: A classic example of inverted relief is Table Mountain, Tuolumne County, California . Multiple lava flows filled an ancient fluvial valley that cut westward through the central Sierra Nevada range to the Central Valley about 10.5 million years ago. These Miocene lava flows filled this ancient river valley with

140-508: The former Gau which is located within the German state of Baden-Württemberg . This region, also called the Hegauer Kegelbergland ( lit.   ' Hegau conical hill landscape ' ), is a Young Drift morainic landscape marked by the remains of several extinct volcanoes, the Hegau volcanoes , which are located mostly to the west and east of the line from Singen (Hohentwiel) in

154-456: The original high ridges of resistant quartzitic sandstone of the Cape Fold Belt were eroded away first, exposing less resistant rock, which eroded faster, leaving the original valley bottom at the top of the residual mountain. Inverted relief in the form of sinuous and meandering ridges, which are indicative of ancient, inverted fluvial channels, is argued to be evidence of water channels on

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168-470: The past volcanisms, several maars formed in the area, which later filled with water to form lakes. The sediments of these maar lakes preserve exceptional fossils , for example of the early horse Hippotherium primigenium or of the giant salamander Andrias scheuchzeri . During the Middle Ages , fortresses were built on top of several Hegau volcanoes. The arguably best-known of the Hegau volcanoes

182-410: The south to Geisingen in the north. The Hegau volcanoes are national geotopes of Germany. The Hegau region, situated at about 400 m (1,300 ft) a.s.l. , is surmounted by nearly a dozen conical hills , which are between 643 m (2,110 ft) and 867 m (2,844 ft) high and which correspond to the remains of the pipes of past volcanoes. The area was volcanically active during

196-690: Was a Gau of the Duchy of Swabia, first mentioned in 787 A.D. in the Latinised form in pago Egauinsse . Its area reached from the Überlinger See of Lake Constance and the city of Konstanz in the east to the Randen and Schaffhausen in the present-day Swiss canton of Schaffhausen in the west. Towards south, it extended to the High Rhine and to the north until the Danube . Today, Hegau refers only to that part of

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