Side valley
Encyclopedia
The terms side valley and tributary valley refer to valley
s whose brook or river
is confluent to a greater one.
Upstream, the valleys can be classified
in an increasing order which is equivalent to the usual orographic order: the tributaries are ordered from those nearest to the source of the river
to those nearest to the mouth of the river
. A confluence
is where two or more tributaries or rivers flow together.
river has order n+1, if n describes the primary (or main) river. A river which flows directly into the ocean
(e.g. the English rivers Thames or Humber
) has the orographic order n=1, the River Ouse
n=2, the Wharfe
n=3 and so on.
), for the lower valleys often do not show a drastic relief. The reason is a simple one: The "mainstem river
" (into which the secondary river flows) passes much more water than its tributaries and therefore
The higher the order of a valley, the steeper usually are the hill
sides resp. valley slope
s. Looking upstream, the steepest slopes are normally near the source of a brook (with the exception of very hard rocks in downstream direction).
of broad rivers lies rather in flat regions (river flats) than of rivers in higher elevation. Therefore the height difference of the tributary near its mouth
is small (e.g. 1 m per km) - but much more at waters of higher order (in the Alps
up to 100 m per km). This is one reason of the large number of hanging valleys in some mountain ranges (e.g. Salzburg
or Graubünden
).
The others are glaciologic or geologic reasons:
All these stages of valley genesis can be seen in higher mountain ranges - e.g. in the "young" Rocky Mountains
, in the "old" ranges and fjord
s of Scandinavia
, or in the Eastern Alps (Salzach
or Inn valley). Just in the Glen
s of Scotland
the type 2 is predominant.
Whereas the valleys near the river flats don't have special forms, the shape of alpine valleys depends much more from the former glaciology and of the rock type.
Like the main valleys described above, the side- or secondary valley can be V-shaped or U-shaped. Also the valley floor varies - from just a few meters up to some 100 m (e.g. Bad Gastein
or St. Moritz
, where small towns have been developed instead of 1000 or 1500 m altitude.
Some valleys are stepped in longitudinal direction (German "Talstufe") which means that these zones show a quicker current
than in average. Therefore the brook will dig its own narrow canal, and the eroded sediments are deposed at the end of each clammy, forming a series of local plain
s. They are an important basis of traditional mountain farming because of excellent places for alpine agriculture
or pasture
s.
: The descriptive terms right or left side-valley (resp. tributary) always apply from the perspective of looking downstream
(in the direction the current
is going).
Sandbanks
: often at reaches with slow current, especially near the river banks. Looking at the various rock types of the gravel
is an excellent and cheap survey
for a summarized geology
of the rivers watershed
(catchment area).
Valley forks: at most confluence
s it is clear which stream is the main river and which is the tributary - as one stream is both much longer and carrying clearly more water than the other. It can, however, happen that one stream is longer, but the other carries more water. This case has no fixed rules to decide. Usually the longer valley is chosen as the main valley, e.g. for the higher number of village
s.
But in Lowland
s the decision may be arbitrary: In Switzerland
the long Alpine Rhine is chosen as the main stream, although the Aar carries more water for her huge midland area.
In the case of the Mississippi River
(which carries more water) and Missouri River
(which is much longer) the choice is made according to the opposite criterion.
Valley
In geology, a valley or dale is a depression with predominant extent in one direction. A very deep river valley may be called a canyon or gorge.The terms U-shaped and V-shaped are descriptive terms of geography to characterize the form of valleys...
s whose brook or river
River
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...
is confluent to a greater one.
Upstream, the valleys can be classified
Categorization
Categorization is the process in which ideas and objects are recognized, differentiated and understood. Categorization implies that objects are grouped into categories, usually for some specific purpose. Ideally, a category illuminates a relationship between the subjects and objects of knowledge...
in an increasing order which is equivalent to the usual orographic order: the tributaries are ordered from those nearest to the source of the river
Source (river or stream)
The source or headwaters of a river or stream is the place from which the water in the river or stream originates.-Definition:There is no universally agreed upon definition for determining a stream's source...
to those nearest to the mouth of the river
River delta
A delta is a landform that is formed at the mouth of a river where that river flows into an ocean, sea, estuary, lake, reservoir, flat arid area, or another river. Deltas are formed from the deposition of the sediment carried by the river as the flow leaves the mouth of the river...
. A confluence
Confluence
Confluence, in geography, describes the meeting of two or more bodies of water.Confluence may also refer to:* Confluence , a property of term rewriting systems...
is where two or more tributaries or rivers flow together.
Orographic order (e.g. river Humber)
In the orographic classification (order of rivers) the tributaryTributary
A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...
river has order n+1, if n describes the primary (or main) river. A river which flows directly into the ocean
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
(e.g. the English rivers Thames or Humber
Humber
The Humber is a large tidal estuary on the east coast of Northern England. It is formed at Trent Falls, Faxfleet, by the confluence of the tidal River Ouse and the tidal River Trent. From here to the North Sea, it forms part of the boundary between the East Riding of Yorkshire on the north bank...
) has the orographic order n=1, the River Ouse
River Ouse, Yorkshire
The River Ouse is a river in North Yorkshire, England. The river is formed from the River Ure at Cuddy Shaw Reach near Linton-on-Ouse, about 6 miles downstream of the confluence of the River Swale with the River Ure...
n=2, the Wharfe
River Wharfe
The River Wharfe is a river in Yorkshire, England. For much of its length it is the county boundary between West Yorkshire and North Yorkshire. The name Wharfe is Celtic and means "twisting, winding".The valley of the River Wharfe is known as Wharfedale...
n=3 and so on.
Basic facts of Geomorphology
However, the term "side valley" is used rather for higher order valleys near the mountains (example above: the PenninesPennines
The Pennines are a low-rising mountain range, separating the North West of England from Yorkshire and the North East.Often described as the "backbone of England", they form a more-or-less continuous range stretching from the Peak District in Derbyshire, around the northern and eastern edges of...
), for the lower valleys often do not show a drastic relief. The reason is a simple one: The "mainstem river
Main Stem
"Main Stem" is 1942 instrumental by Duke Ellington and His Famous Orchestra. Although recorded in 1942, the single would not be released until 1944 where it was Duke Ellington's last of four number one's on the Harlem Hit Parade. "Main Stem" would also peak at number twenty on the pop chart"Main...
" (into which the secondary river flows) passes much more water than its tributaries and therefore
- has a lower current (see HydrologyHydrologyHydrology is the study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability...
) - much more fine sedimentSedimentSediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
s - which are deposed in a more flat matter.
The higher the order of a valley, the steeper usually are the hill
Hill
A hill is a landform that extends above the surrounding terrain. Hills often have a distinct summit, although in areas with scarp/dip topography a hill may refer to a particular section of flat terrain without a massive summit A hill is a landform that extends above the surrounding terrain. Hills...
sides resp. valley slope
Hill
A hill is a landform that extends above the surrounding terrain. Hills often have a distinct summit, although in areas with scarp/dip topography a hill may refer to a particular section of flat terrain without a massive summit A hill is a landform that extends above the surrounding terrain. Hills...
s. Looking upstream, the steepest slopes are normally near the source of a brook (with the exception of very hard rocks in downstream direction).
Hanging valleys
The estuaryEstuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
of broad rivers lies rather in flat regions (river flats) than of rivers in higher elevation. Therefore the height difference of the tributary near its mouth
Mouth
The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....
is small (e.g. 1 m per km) - but much more at waters of higher order (in the Alps
Alps
The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....
up to 100 m per km). This is one reason of the large number of hanging valleys in some mountain ranges (e.g. Salzburg
Salzburg
-Population development:In 1935, the population significantly increased when Salzburg absorbed adjacent municipalities. After World War II, numerous refugees found a new home in the city. New residential space was created for American soldiers of the postwar Occupation, and could be used for...
or Graubünden
Graubünden
Graubünden or Grisons is the largest and easternmost canton of Switzerland. The canton shares borders with the cantons of Ticino, Uri, Glarus and St. Gallen and international borders with Italy, Austria and Liechtenstein...
).
The others are glaciologic or geologic reasons:
- The huge glacierGlacierA glacier is a large persistent body of ice that forms where the accumulation of snow exceeds its ablation over many years, often centuries. At least 0.1 km² in area and 50 m thick, but often much larger, a glacier slowly deforms and flows due to stresses induced by its weight...
s of the ice ageIce ageAn ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...
caused a violent erosionErosionErosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
which resulted in many U-shapedValleyIn geology, a valley or dale is a depression with predominant extent in one direction. A very deep river valley may be called a canyon or gorge.The terms U-shaped and V-shaped are descriptive terms of geography to characterize the form of valleys...
"glacial valleys", especially in altitudes of 400–800 m which is typical for alpine main valleys. - At the place where the tributary flew into the river before the glacial period, there is now a valley shoulder (see figure). The side valley has to lose a lot of its height and is developing into a hanging valley.
- In previous rock like limestoneLimestoneLimestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
) the side-valley will become a gorge or a clammy. - In graniteGraniteGranite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...
or other crystalline areas a waterfallWaterfallA waterfall is a place where flowing water rapidly drops in elevation as it flows over a steep region or a cliff.-Formation:Waterfalls are commonly formed when a river is young. At these times the channel is often narrow and deep. When the river courses over resistant bedrock, erosion happens...
may be the result.
- In previous rock like limestone
All these stages of valley genesis can be seen in higher mountain ranges - e.g. in the "young" Rocky Mountains
Rocky Mountains
The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...
, in the "old" ranges and fjord
Fjord
Geologically, a fjord is a long, narrow inlet with steep sides or cliffs, created in a valley carved by glacial activity.-Formation:A fjord is formed when a glacier cuts a U-shaped valley by abrasion of the surrounding bedrock. Glacial melting is accompanied by rebound of Earth's crust as the ice...
s of Scandinavia
Scandinavia
Scandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...
, or in the Eastern Alps (Salzach
Salzach
The Salzach is a river in Austria and Germany. It is a right tributary of the Inn and is 225 kilometres in length.The river's name is derived from the German word Salz, meaning "salt". Until the 19th century shipping of salt down the river was an important part of the local economy...
or Inn valley). Just in the Glen
Glen
A glen is a valley, typically one that is long, deep, and often glacially U-shaped; or one with a watercourse running through such a valley. Whittow defines it as a "Scottish term for a deep valley in the Highlands" that is "narrower than a strath."...
s of Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
the type 2 is predominant.
Shape of side valleys
Like the main valleys described above, the side- or secondary valley can be V-shaped or U-shaped. Also the valley floor varies - from just a few meters up to some 100 m (e.g. Bad Gastein
Bad Gastein
Bad Gastein is a spa town in the Austrian state of Salzburg, situated at the northern rim of the Hohe Tauern national park. It has 5,838 inhabitants. The name "Bad" means "spa", reflecting the town's history as a health resort. It is located at the head of the Gastein valley, about 1,000 metres ...
or St. Moritz
St. Moritz
St. Moritz is a resort town in the Engadine valley in Switzerland. It is a municipality in the district of Maloja in the Swiss canton of Graubünden...
, where small towns have been developed instead of 1000 or 1500 m altitude.
Some valleys are stepped in longitudinal direction (German "Talstufe") which means that these zones show a quicker current
Current (stream)
A current, in a river or stream, is the flow of water influenced by gravity as the water moves downhill to reduce its potential energy. The current varies spatially as well as temporally within the stream, dependent upon the flow volume of water, stream gradient, and channel geometrics...
than in average. Therefore the brook will dig its own narrow canal, and the eroded sediments are deposed at the end of each clammy, forming a series of local plain
Plain
In geography, a plain is land with relatively low relief, that is flat or gently rolling. Prairies and steppes are types of plains, and the archetype for a plain is often thought of as a grassland, but plains in their natural state may also be covered in shrublands, woodland and forest, or...
s. They are an important basis of traditional mountain farming because of excellent places for alpine agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
or pasture
Pasture
Pasture is land used for grazing. Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, cattle, sheep or swine. The vegetation of tended pasture, forage, consists mainly of grasses, with an interspersion of legumes and other forbs...
s.
Miscellaneous
OrographyOrography
Orography is the study of the formation and relief of mountains, and can more broadly include hills, and any part of a region's elevated terrain...
: The descriptive terms right or left side-valley (resp. tributary) always apply from the perspective of looking downstream
Source (river or stream)
The source or headwaters of a river or stream is the place from which the water in the river or stream originates.-Definition:There is no universally agreed upon definition for determining a stream's source...
(in the direction the current
Current (stream)
A current, in a river or stream, is the flow of water influenced by gravity as the water moves downhill to reduce its potential energy. The current varies spatially as well as temporally within the stream, dependent upon the flow volume of water, stream gradient, and channel geometrics...
is going).
Sandbanks
Sandbanks
Sandbanks is a small peninsula or spit crossing the mouth of Poole Harbour on the English Channel coast at Poole in Dorset, England. It is well-known for the highly regarded Sandbanks Beach and property value; Sandbanks has, by area, the fourth highest land value in the world...
: often at reaches with slow current, especially near the river banks. Looking at the various rock types of the gravel
Gravel
Gravel is composed of unconsolidated rock fragments that have a general particle size range and include size classes from granule- to boulder-sized fragments. Gravel can be sub-categorized into granule and cobble...
is an excellent and cheap survey
Geological survey
The term geological survey can be used to describe both the conduct of a survey for geological purposes and an institution holding geological information....
for a summarized geology
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
of the rivers watershed
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...
(catchment area).
Valley forks: at most confluence
Confluence
Confluence, in geography, describes the meeting of two or more bodies of water.Confluence may also refer to:* Confluence , a property of term rewriting systems...
s it is clear which stream is the main river and which is the tributary - as one stream is both much longer and carrying clearly more water than the other. It can, however, happen that one stream is longer, but the other carries more water. This case has no fixed rules to decide. Usually the longer valley is chosen as the main valley, e.g. for the higher number of village
Village
A village is a clustered human settlement or community, larger than a hamlet with the population ranging from a few hundred to a few thousand , Though often located in rural areas, the term urban village is also applied to certain urban neighbourhoods, such as the West Village in Manhattan, New...
s.
But in Lowland
Lowland
In physical geography, a lowland is any broad expanse of land with a general low level. The term is thus applied to the landward portion of the upward slope from oceanic depths to continental highlands, to a region of depression in the interior of a mountainous region, to a plain of denudation, or...
s the decision may be arbitrary: In Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
the long Alpine Rhine is chosen as the main stream, although the Aar carries more water for her huge midland area.
In the case of the Mississippi River
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
(which carries more water) and Missouri River
Missouri River
The Missouri River flows through the central United States, and is a tributary of the Mississippi River. It is the longest river in North America and drains the third largest area, though only the thirteenth largest by discharge. The Missouri's watershed encompasses most of the American Great...
(which is much longer) the choice is made according to the opposite criterion.