Mountains and Valleys
Mountains and valleys are natural landforms that coexist. Mountain is a part of Earth’s crust at an elevation. But, a valley is a low area lying between mountains of lower, elevated landforms. Mountains and valleys coexisting give nature’s most beautiful gift and a treat for your eyes. Both mountains and valleys are important geographical regions for human survival.
Although both these land structures form through a natural process, they vary. These two landforms are pretty different from each other. There are different types of mountains formed by different processes. The formation of a valley is also a diverse natural process. The construction of these structures is unique and can be studied on its own.
Let us now see how mountains and valleys differ from each other. These differences occur due to structure, formation, climate, and settlement activities.
Here is a detailed discussion on mountains and valleys.
A mountain is an elevated area of the Earth’s crust with steep sides. These structures have a large amount of bedrock exposed. Although definitions of a mountain fluctuate, it is often taller than a hill. Most mountains rise at least 300 meters above the surrounding terrain and differ from a plateau with a constrained peak area. Most mountains are found in mountain ranges, while a handful has isolated summits.
Mountain formation occurs due to tectonic processes, erosion, or volcanism. These activities can take tens of millions of years or longer to manifest. Mountain ranges flatten over time when mountain-building stops due to weathering, slumping, and other forms of mass wasting. Many conditions of erosion by rivers and glaciers could also cause the building to stop.
Climates on mountains with high heights are colder than those at equal latitudes at sea level. These cooler climates have a major impact on the ecosystems of mountains. Hence, different elevations have diverse plants and animals. Mountains have less favorable terrain and weather, so they are utilized less for agriculture and more for resource extraction and recreation. Mining and logging within the mountain rocks are extraction activities of the mountains. People also do activities like mountain climbing and skiing as mountain recreation activities.
The highest peak on Earth, Mount Everest in Asia’s Himalayas, rises 8,849 meters above the mean sea level at its top. Olympus Mons, which lies on Mars, is the highest known mountain on any planet in the Solar System at 21,171 meters.
Types of mountains
Mountain’s classifications are of different types based on their formation. The major types of mountains are:- volcanoes, fold mountains and erosion mountains. Let us break down the formation of these mountains in detail.
A volcano is a crack in a planetary-mass object like Earth’s crust. These cracks allow gases, hot lava, and volcanic ash to escape from a magma chamber. These chambers lie beneath the Earth’s surface.
Volcanoes are created at a mid-ocean ridge or hotspot. The formation occurs when one plate pushes beneath another. Around 100 km below the surface, the rock above the slab begins to melt, creating lava that rises to the surface. A shield volcano or a stratovolcano is one of the volcanic mountains that form when magma reaches the surface. The volcanoes Mount Fuji in Japan and Mount Pinatubo in the Philippines are two examples.
It is not necessary for magma to reach the surface to produce a mountain, though. Magma solidifying underground can still form dome mountains like the US’s Navajo Mountain.
Volcanoes also come in different types as well. The functions of these volcanoes also vary per their types.
Fold mountains are peaks formed due to the folding of layers along the upper part of the Earth’s crust. The word fold mountain has been in use since scientists understood tectonic plates and thrust belts. People used the term fold mountains to refer to mountain belts like the Himalayan range.
Mountains with folds develop in thrust tectonic regions. At the convergent plate border, two tectonic plates move in the same direction. The piled rock layers may fold and crumple like a tablecloth when plates and the continents riding on the plates contact. It occurs if a layer that is weak within its mechanics, like salt.
Denser mantle rocks are underneath the less thick continental crust. There must be a balance of any crustal material driven upward to form mountains, plateaus, or hills. A considerable, larger volume must push down into the mantle with more force. Thus, the continental crust has significant thicknesses under mountains compared to lower-lying locations. Asymmetrical or symmetrical folding of rock is possible.
Some examples of Fold mountains include the Northern Range of Trinidad, the Alps, the Himalayas, the Andes, the Blue Mountains of Jamaica, and the Rockies. The tallest peak of the world, Everest, is also a fold mountain.
Mountains have to face erosion during and after the uplift. Erosion aids in mountain formation and also causes gradual degradation of the raised area. Mountains’ surfaces are younger than the underlying rocks because of erosion. The erosion of a raised plateau creates plateau mountains. Catskill mountain range of southeast New York is an example of such a mountain.
Besides shaping mountains, erosion directs tectonic movements deep beneath the crust. Gravity is the primary constraining factor for mountain growth. Hence, erosion quickens the tectonic processes. As erosion takes place beneath the mountains, it lowers the weight of the mountain range. Because of this, erosional processes can is like “sucking” crust up toward the surface. Such crusts end up forming mountain ranges.
Hence, crustal deformation in and beneath mountains and the rocks carry imprints of erosion.
The local climate and erosion determine the type of rock that makes up a mountain’s surface. Erosion has an impact on mountain composition and structure besides topography. The pressure and temperature distribution inside the crust controls how rocks metamorphose. They also affect how many rock-forming minerals form.
As a mountain range develops, few elements can have a significant impact on the mountain. Such elements include climate and erosion due to wind direction and speed or slight variations in latitude. These factors affect temperature history and, so, the type of mountain rocks.
Most plateau mountains are examples of erosion mountains.
Climate of mountains
The higher your height, the colder it gets in the mountains. Climates in the mountains have more substanial humidity than those in the nearby flat area. The weather in the mountains can change from one hour to the next. When the sky is completely clear, a thunderstorm may appear in a matter of minutes. Following that, temperatures may decrease from very high levels to below freezing.
The climate varies depending on where you are on a mountain and its altitude. While the peaks may have ice coverage, the foothills may have a tropical environment. Mountains’ highest point is frequently of only bare rock and snow. Examples include the Himalayas, Tibet, and other mountain ranges like the Rocky or Andes.
The altitude of the mountains causes the climate to get cooler. This occurs because air thins out and loses its capacity to absorb and hold heat as altitude rises. Less evaporation occurs at lower temperatures, resulting in more air moisture.
The top of the mountain’s temperature is lower than at the bottom. So, snow can cover the top of the mountain year-round. The temperature will be colder the higher above sea level the location is. The chilly mountain air results from air pressure drop with elevation. Rising air expands and cools as a result of the decreased air pressure.
Moist air is spread throughout the land by winds. Due to the obstruction caused by the mountains, the air that reaches the peak rises. Because cool air can carry less moisture than warm air as it rises, precipitation occurs. Since mountains have lower temperatures than sea levels, they experience more rainfall than low-lying locations.
Some mountains are higher than the clouds. Blizzards develop at this height due to the intense cold and strong winds.
Mountains can also influence the nearby climate of neighboring lands. Numerous biological zones occur nearby, ranging from lush tropical jungles to glacial ice. These places are “stacked” onto one another due to the fast changes in height and temperature along a mountain slope. Mountains can prevent rain in some areas, resulting in rain on one side and a desert on the other.
Human settlement in mountains
Fewer people live in mountainous locations because of the severe climate. In the mountains, there are two major different house patterns that exist.
The first kind of settlement is the dispersed settlement. The houses in these towns spread all over a vast region. The mud-built homes have low roofs. Clustered settlements make up the second form of settlement. All the homes are gathered together in such villages on a single slope. The dwellings can be joined wall to wall and have formations of wood.
Mountains have a very small population which natives populate. These indigenous people used or resided in the highlands for thousands of years. They lived as hunters and gatherers initially, followed by farmers and pastoralists.
These remote mountain communities have a diverse population of cultures and languages. Approximately 720 million people, or 12% of the global population, live in mountainous areas. Numerous mountain locals are disadvantaged politically and economically.
The people who live in the mountains adjust to the severe weather. However, less developed countries frequently experience poor health and food insecurity. They are poor and rely on farming, livestock, and forest goods. The mountain people are often well-off in the developed world. The mountains are famous for sports and for, outdoor recreation and tourism.
A valley is a long, low terrain typically between hills or mountains. A river or stream usually flows through a valley from one end to the other. Most valleys are created by rivers or streams eroding the ground’s surface over a very long period.
Some valleys develop as a result of glacial ice erosion. These glaciers could still exist in valleys of high mountains or polar regions. These glacial valleys expanded at lower latitudes and elevations during ice eras. But now that the ice has melted, streams and rivers may move through them.
Valleys in arid regions may be completely dry or only sometimes carry a river. Dry valleys may also result from drainage occurring underground rather than at the surface in locations with limestone bedrock.
Another valley type is a rift valley that forms due to earth movements instead of erosion. Geographers identify a wide variety of valley types. Let’s go over a few of them in more detail.
Types of valleys
There are two significant ways through which valleys form. Some valleys form by bedrock erosion due to moving water bodies like rivers. But, valleys also form by the force of glacial ice on the bottom layers of mountain rocks. Let us discuss these valleys and their formation in detail.
The river or stream’s bedrock causes river valleys to form. In addition to the climate, the elevational difference between its top and bottom contributes to its creation. The gradient of formation usually decreases as the flow increases downstream.
In the case of upper valleys, the stream will most efficiently erode the bed by corrosion. The erosion causes to create a steep-sided V-shaped valley. The stream’s path may be determined by the existence of more durable rock bands and folds. Such a road could lead to a twisting path with interconnecting spurs.
In middle valleys, multiple streams unite; the valley is often broader. The river flow here is slower, and erosion and deposition are possible. Strong currents outside a river’s bend erode the bank more severely in the middle of the river’s journey. On the other hand, where the current is substantially slower, deposition may occur. Such depositions give the river a meandering appearance.
The lower valleys have gradients that are at the lowest. But the meanders may be significantly more expansive. So, the resulting floodplain may be larger in the lower valley. Erosion is subordinate to deposition. Each of these several types of valleys is present in a typical river basin or drainage basin.
Some examples of river valleys are the Ganes, Indus Yellow River, Nile, Tigris-Euphrates, etc. All these valleys are part of ancient civilizations.
Various valleys form through association with glaciers. Glaciers have carved out true glacial valleys, whether they still exist today. These valleys could alternatively go by the name of glacial troughs. They are common landforms in mountainous regions where glaciation has occurred. Such a glacial process could still be occurring. These valleys typically have a U-shaped cross-section.
A glacial valley’s highest point has one or more “cirques,” or hollows. These types of structures resemble armchairs. The rotational movement of a cirque glacier downslope creates these hollows.
Glaciers initially formed during the glacier period. Then the ice age continued to extend these glaciers downhill.
The spreading and deepening of the valley results in the typical U-shaped or trough shape. Such valleys have steep, even vertical sides and a relatively flat bottom. Such structure results from abrasion by the movement of the ice. To be specific, it is due to the rock debris within it.
Truncated spurs, typical of glaciated mountain landscapes, are produced by erosion. These erosions are the result of interlocking spurs connected to the formation of river basins. A trough-end could be the top of the trough beneath the cirques that provide ice. The bedrock has unique characteristics and the sliding ice’s force. Hence the bedrock causes valley steps to develop at varying erosion rates.
Glacial valleys have two major types:- tunnel valleys and meltwater valleys.
A tunnel valley is a big, long, U-shaped valley. Such valleys form due to carving beneath glacial ice close to the edge of continental ice sheets.
Meltwater valleys are, but, mostly part of central Europe. The Scandinavian ice sheet moved a little uphill against the terrain during the ice ages. Such movement of ice sheets resulted in Meltwater valleys.
Yosemite Valley of the United States and the Side valleys of Austria are some examples of glacial valleys.
Climate of valleys
In valleys, there may be changes in humidity, day length, daytime temperature, and wind. Valleys have lower elevations; the temperature is frequently warmer throughout the day. Air that descends into the valley will also warm due to a process called adiabatic fall. The polar opposite can take place at night. Due to its greater density, colder air will tend to sink to the valley’s lower elevations. Longer nights and colder temperatures may occur in some instances. This happens if the higher altitudes’ positions cause to obstruct the sun. The obstruction affects the sunrise and sunset.
In the valley, interesting meteorological phenomena can occur. The moisture’s amount increases when a river or stream often passes through a valley. Similarly, the lower nighttime temperatures may cause valley fog and clouds. The valley may experience fog, clouds, or smog during the day if an inversion is present.
Strong winds could occur in a valley as they can funnel air moving between structures. This may cause the valley to have more vital wind occurrences than those in the nearby locations.
The higher elevation regions’ orientation can impact the day’s length. The sun’s rise and set won’t have significant obstructions if the higher heights run east-west. But, the amount of time the sun may direct beam on the valley can be considerably reduced. The reduction occurs only if the higher hills run north-south. So, valleys that run north to south have a chance of being substantially cooler.
Since streams unite and run through the valley, the humidity can be higher there. As a result, the kind, variety, and density of plants in the valley area may grow. Additionally, it may result in more fog episodes. Such fogs are more than what is common compared in higher elevations.
Human settlements in valleys
The human settlements started in valleys and survived in river valleys. The ancient human civilizations lived near rivers due to easy access to water. Hence, this led to river valleys being the core settlement area for humans.
Rivers have offered the simplest or the only means of access and movement throughout history. They are significant landmarks for explorers, traders, conquerors, and settlers. The fall of the Roman Empire resulted in the splintering of river routes. They gained great significance throughout Europe. Regardless of governmental structures, control of crossing locations manifested in fortresses and the rise of bridge towns.
In medieval Europe, rivers served as a supply of clean water for cities. Rivers were also a means of removing trash from them. They were also exploited as power sources, by direct means or by offtakes.
Valleys in the modern world are a part of the urbanized and industrialized world. Most valleys are the cornerstone of development for any country. As humans evolved, they kept their settlements near rivers. The river valleys ended up being the most populated human settlement areas. So, the modern industrialized society has its marks in settlement valley areas.
The glacial valleys, on the other hand, are not as populated as river valleys. Landforms formed by glacial erosion have an impact on human activities in the area of transportation. Eroded U-shaped glacial valleys have several benefits for modes of transportation. Such valleys offer upland areas with natural passageways. So that important towns can connect high and then help to build railway lines.
Mountain regions housing glacial valleys have benefited from the economic point of view of the recent explosive rise of the tourism sector. A positive economic impact of tourism is the multiplier effect. Pyramidal peaks, corries, deep valleys, arêtes, and hanging valleys are just a few of the stunning eroded glacial features. These stunning features of glacial valleys attract a lot of tourists.