Munich gravel plain
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The Munich gravel plain (german: Münchner Schotterebene) is an
outwash plain An outwash plain, also called a sandur (plural: ''sandurs''), sandr or sandar, is a plain formed of glaciofluvial deposits due to meltwater outwash at the terminus of a glacier. As it flows, the glacier grinds the underlying rock surface and c ...
in
Upper Bavaria Upper Bavaria (german: Oberbayern, ; ) is one of the seven administrative districts of Bavaria, Germany. Geography Upper Bavaria is located in the southern portion of Bavaria, and is centered on the city of Munich, both state capital and seat o ...
, Germany, formed during
Late Pleistocene The Late Pleistocene is an unofficial Age (geology), age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a Stratigraphy, stratigraphic perspective. It is intended to be the fourth division of ...
glacial period A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betw ...
s. Characterized by its very wide extension, it comprises sandur terraces and the floodplain of the
Isar The Isar is a river in Tyrol, Austria, and Bavaria, Germany, which is not navigable for watercraft above raft size. Its source is in the Karwendel range of the Alps in Tyrol; it enters Germany near Mittenwald and flows through Bad Tölz, Munic ...
river. These most recent deposits overlie the
Neogene The Neogene ( ), informally Upper Tertiary or Late Tertiary, is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period Mya. ...
Molasse basin The Molasse basin (or North Alpine foreland basin) is a foreland basin north of the Alps which formed during the Oligocene and Miocene epochs. The basin formed as a result of the flexure of the European plate under the weight of the orogenic ...
of the
Alpine Foreland The Alpine Foreland, less commonly called the Bavarian Foreland,Dickinson, Robert E (1964). ''Germany: A regional and economic geography'' (2nd ed.). London: Methuen, pp. 585-586. . Bavarian Plateau or Bavarian Alpine Foreland (german: Bayerisches ...
, which in contrast comprises fine-grained fluviatile and
lacustrine A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...
facies In geology, a facies ( , ; same pronunciation and spelling in the plural) is a body of rock with specified characteristics, which can be any observable attribute of rocks (such as their overall appearance, composition, or condition of formatio ...
.


Location

The plain covers a triangular area of around 1500 km2 (= 579.15 mi2). The three corners corresponded with the town of
Weyarn Weyarn is a municipality in the district of Miesbach in Bavaria in Germany. It dates back to a monastery that was founded by Siboto II, count of Falkenstein in 1133. It is located 38 km southeast of Munich and can be easily reached on hig ...
, between
Miesbach Miesbach () is a town in Bavaria, Germany, and is the capital of the Miesbach district. The district is at an altitude of 697 metres above sea level. It covers an area of approximately 863.50 km² of alpine headlands and in 2017 had a popu ...
and Holzkirchen in the southeast, Moosburg an der Isar in the northeast and
Maisach Maisach is a municipality in the district of Fürstenfeldbruck, in Bavaria, Germany. Maisach is the largest municipality in the Fürstenfeldbruck district. It is situated north of Fürstenfeldbruck, and northwest of Munich. It is served by an ...
in the west.
Munich Munich ( ; german: München ; bar, Minga ) is the capital and most populous city of the States of Germany, German state of Bavaria. With a population of 1,558,395 inhabitants as of 31 July 2020, it is the List of cities in Germany by popu ...
city and nearly all its peripheral districts are situated on top of the flat gravel plain. As a consequence the city, in contrast to the surrounding counties in the north, south and west, has almost no
topographic Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary scie ...
features. However, the waters of the Isar river have cut into the
Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...
ground in several stages and caused the typical terrace levels within the city. The plain drops to the northeast from initially around above sea level to approximately , a decisive factor for the formation of the large Dachauer Moors, the Freisinger Moor and the Erdinger Moor. The
gravel Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone. Gravel is classifi ...
deposits of are the deepest in the south of Munich and decrease towards the north.


Formation

According to an unambiguous
stratigraphic Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithostrati ...
record the formation process extended over three
glacial period A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betw ...
s. The massive Central Alpine pleistocene glaciers, that almost reached to the area of modern Munich, discharged not only water but also large amounts of soil and rock into the
Alpine Foreland The Alpine Foreland, less commonly called the Bavarian Foreland,Dickinson, Robert E (1964). ''Germany: A regional and economic geography'' (2nd ed.). London: Methuen, pp. 585-586. . Bavarian Plateau or Bavarian Alpine Foreland (german: Bayerisches ...
. When the glaciers melted during
interglacial An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene in ...
warm periods, huge quantities of gravel, debris and water were released and flushed to the north, where they were mainly deposited on the Munich gravel plain. The lowest strata contains solidified deposits from the
Mindel glaciation The Mindel glaciation (german: Mindel-Kaltzeit, also ''Mindel-Glazial'', ''Mindel-Komplex'' or, colloquially, ''Mindel-Eiszeit'') is the third youngest glacial stage in the Alps. Its name was coined by Albrecht Penck and Eduard Brückner, who nam ...
, above it lies gravel from the
Riss glaciation The Riss glaciation, Riss Glaciation, Riss ice age, Riss Ice Age, Riss glacial or Riss Glacial (german: Riß-Kaltzeit, ', ' or (obsolete) ') is the second youngest glaciation of the Pleistocene epoch in the traditional, quadripartite glacial classi ...
, which in turn is covered by the youngest layer, the rock scree from the
Würm glaciation The Würm glaciation or Würm stage (german: Würm-Kaltzeit or ''Würm-Glazial'', colloquially often also ''Würmeiszeit'' or ''Würmzeit''; cf. ice age), usually referred to in the literature as the Würm (often spelled "Wurm"), was the last g ...
. Layers of clay in between represent the interim humus collections of the respective interglacial periods. All these ice age gravel deposits lie on top of the low hydraulic conductive sediments of the
Molasse basin The Molasse basin (or North Alpine foreland basin) is a foreland basin north of the Alps which formed during the Oligocene and Miocene epochs. The basin formed as a result of the flexure of the European plate under the weight of the orogenic ...
. The basin's sediment material of conglomerates, shales and debris have accumulated by erosion and denudation and formed in a sequence during the development of the Alps between around 50 to 3 million years ago. These layers, locally referred to as ''Flinz'' are impermeable to water.


Waters

During the pleistocene the ancient
Mangfall The Mangfall is a river of Upper Bavaria, Germany. The Mangfall is the outflow of the Tegernsee lake and discharges in Rosenheim from the left into the Inn. It is long. Towns and villages on the Mangfall * Gmund am Tegernsee * Valley * Weyar ...
river flowed through the eastern section of what is now the Munich gravel plain before it was deflected to the east towards the Inn river by a
Würm glaciation The Würm glaciation or Würm stage (german: Würm-Kaltzeit or ''Würm-Glazial'', colloquially often also ''Würmeiszeit'' or ''Würmzeit''; cf. ice age), usually referred to in the literature as the Würm (often spelled "Wurm"), was the last g ...
moraine A moraine is any accumulation of unconsolidated debris (regolith and rock), sometimes referred to as glacial till, that occurs in both currently and formerly glaciated regions, and that has been previously carried along by a glacier or ice shee ...
. The Grub-Harthausen
dry valley A dry valley may develop on many kinds of permeable rock, such as limestone and chalk, or sandy terrains that do not regularly sustain surface water flow. Such valleys do not hold surface water because it sinks into the permeable bedrock. There ...
is a sector of the former course of the river. Today the
Isar The Isar is a river in Tyrol, Austria, and Bavaria, Germany, which is not navigable for watercraft above raft size. Its source is in the Karwendel range of the Alps in Tyrol; it enters Germany near Mittenwald and flows through Bad Tölz, Munic ...
river is the largest body of water on the Munich gravel plain. It roughly equally bisects the plain from southwest to northeast. Coming from the district of Starnberg, the
Würm The Würm is a river in Bavaria, Germany, right tributary of the Amper. The length of the river is , or including the ''Steinbach'', the main feed of Lake Starnberg. It drains the overflow from Lake Starnberg and flows swiftly through the villag ...
river flows through the west of the Munich gravel plain. Further natural waters are the
Hachinger Bach The Hachinger Bach is a river in Bavaria, Germany. It flows southwards of Munich, through the townships of Oberhaching, Taufkirchen, Unterhaching and Unterbiberg, and enters the Munich city area in Perlach. It is twelve kilometers long. Th ...
and the Gröbenbach and its tributaries, which all, due to exudation of groundwater, rise on the Munich gravel plain.


Groundwater

In the south, the gravel layer of the groundwater-rich Munich gravel plain is the most massive. The top groundwater layer at the Haar-Eglfing measuring point is more than below ground, in Kirchheim it is around and on the northern edge of the Munich gravel plain it is less than . These levels used to be higher. The Erdinger Moos, which begins north of the municipalities of Aschheim, Kirchheim and Pliening, was once a bog where groundwater surfaced. The outlying communities in the north were frequently flooded after heavy rainfall. To prevent future flooding, a drainage ditch was built in the early 1920s, which caused the groundwater table to drop significantly, which in turn required deeper wells to be dug in these communities. The
Thickness Thickness may refer to: * Thickness (graph theory) * Thickness (geology), the distance across a layer of rock * Thickness (meteorology), the difference in height between two atmospheric pressure levels * Thickness planer a woodworking machine ...
of the gravel layer in the south of the Munich gravel plain made it hard to get to the groundwater for the first settlers during the early Middle Ages. This, however, was essential, as there were no surface waters like ponds or lakes. People settled around the local wells and the settlements were named after the owners of these precious water sources, such as
Putzbrunn Putzbrunn is a town in the district of Munich, Bavaria in Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most pop ...
(once Puzzoprunnin after a Puzzo) or
Grasbrunn Grasbrunn is a municipality in the district of Munich in Bavaria in Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and th ...
(Gramasprunnin after a Gramas or Graman).


Economic significance

The surface gravel and sand deposits have been exploited for use in construction for a long time. There still remain several sand and gravel plants as in Grasbrunn and at
Aschheim Aschheim is a small town and municipality in the district of Munich in Bavaria in Germany. It lies beyond the northeastern outskirts of Munich. Aschheim is the location of BMW's test track opened by the manufacturer in 1972, and also has a golf ...
. At the site of the modern ''Heimstettener See'' (Heimstetten Lake), gravel was mined for the
Reichsbahn The ''Deutsche Reichsbahn'', also known as the German National Railway, the German State Railway, German Reich Railway, and the German Imperial Railway, was the German national railway system created after the end of World War I from the regiona ...
until 1937. The ''Feringasee'' (Feringa Lake) gravel was used for the construction of the Autobahn A 99 from 1974 to 1976, the ''Böhmerweiher'' (Böhmerweiher Lake) was created between 1993 and 1999 by sand and gravel mining for the construction of the Autobahn A 8. Former gravel pits are also all the lakes of the
Dreiseenplatte Dreiseenplatte is the name of three lakes in Feldmoching-Hasenbergl in the northern part of Munich, Germany. The lakes are: Lerchenauer See, Fasaneriesee and Feldmochinger See. Photos Lerchenauer_See_mit_Blick_nach_Südwesten.jpg, Lerchenauer ...
(Three Lake district), that include the ''Lerchenauer See'', ''Fasanerie See'' and ''Feldmochinger See'' and the three lakes of the
Langwieder lake district The Langwieder lake district (German: Langwieder Seenplatte) is composed of three lakes west of Munich in Bavaria, Germany. It opened in the year 2000 as a recreational area enclosing the Langwieder See, the Lußsee, and the Birkensee. The entire s ...
to the west of Munich. The Langwieder lake district includes the ''Langwieder See'', which provided gravel for the construction of the Autobahn A 8 during the 1930s, the ''Birkensee'', from which gravel was extracted for a railway line in 1938, and the ''Lußsee'', from which gravel was used from 1995 to 2000 for the construction of the ''Eschenrieder Spange'', a shortcut at a junction of the Autobahn A 99. Most of the defunct sand and gravel pits have undergone years of extensive recultivation and have since become popular recreation sites for the inhabitants of metropolitan Munich.


References


External links


Grundwassermodell Östliche Münchner Schotterebene

Homepage of the Miocene Northern Alpine Molasse Zone scientists association
{{coord missing, Bavaria Landforms of Bavaria Glacial landforms Plains of Germany Geography of Munich