Types and types of mountains. What types of mountains are there? The highest mountains in Russia How mountains are divided by age

Mountains vary in height, shape, age, origin, geographical location, etc. The article provides a description of the listed types of mountains.

Mountains by height

Lowlands

Low mountains or low mountains - mountain heights up to 800 meters above sea level.

Peculiarities:

The tops of the mountains are round, flat,
The slopes are gentle, not steep, covered with forest,
Characteristically, there are river valleys between the mountains.

Examples: Northern Urals, spurs of the Tien Shan, some ridges of Transcaucasia, Khibiny Mountains on the Kola Peninsula, individual mountains of Central Europe.

Srednegorye

Middle mountains (medium or mid-altitude mountains) - the height of these mountains is from 800 to 3000 meters above sea level.

Medium-altitude mountains are characterized by altitudinal zonation, i.e. change of landscape with change in altitude.

Examples of medium mountains: Mountains of the Middle Urals, Polar Urals, mountains of the island of Novaya Zemlya, mountains of Siberia and the Far East, mountains of the Apennine and Iberian Peninsulas, Scandinavian mountains in northern Europe, Appalachians in North America, etc.

Highlands

Highlands (high mountains) - the height of these mountains is more than 3000 meters above sea level. These are young mountains, the relief of which is intensively formed under the influence of external and internal processes.

Peculiarities:

The mountain slopes are steep, high,
The peaks of the mountains are sharp, peak-shaped, and have a specific name - “Carlings”,
The mountain ridges are narrow, jagged,
It is characterized by altitudinal zones from forests at the foot of the mountains to icy deserts at the tops.

Examples: Pamir, Tien Shan, Caucasus, Himalayas, Cordillera, Andes, Alps, Karakoram, Rocky Mountains, etc.

Mountains by shape

According to the nature of the summit endings, mountains are: peak-shaped, dome-shaped, plateau-shaped, etc.

Peaked mountain peaks

Peaked mountains are pointed mountain peaks that are shaped like peaks, hence the name of this type of mountain peak. They are characteristic mainly of young mountains with steep rocky slopes, sharp ridges and deep crevices of river valleys.

Examples of mountains with peaked peaks:

Peak Communism (mountain system - Pamir, height 7495 meters)
Pobeda Peak (Tian Shan mountain system, height 7439 meters)
Mount Kazbek (mountain system - Pamir, height 7134 meters)
Pushkin Peak (mountain system - Caucasus, height 5100 meters)

Domed mountain peaks

The dome-shaped, that is, rounded, shape of the top can be taken by:

Laccoliths are unformed volcanoes in the form of a hill with a magma core inside,
Extinct ancient heavily destroyed volcanoes,
Small areas of land that have undergone a dome-shaped tectonic uplift and, under the influence of erosion processes, have taken on a mountainous appearance.

Examples of mountains with a dome-shaped peak:

Black Hills (USA). The area was subject to dome uplift and much of the sedimentary cover was removed by further denudation and erosion. As a result, the central core was exposed. It consists of metamorphic and igneous rocks.
Ai-Nikola (Ukrainian Ai-Nikola, Crimean tat. Ay Nikola, Ai Nikola) is a domed outlier mountain, the southeastern spur of Mount Mogabi near the western outskirts of the village of Oreanda. It is composed of Upper Jurassic limestones. Height - 389 meters above sea level.
Kastel (Ukrainian Kastel, Crimean Catholicate. Qastel, Kaastel) is a mountain 439 m high on the southern outskirts of Alushta, behind the Professor’s Corner. The dome of the mountain is covered with a forest cap, and chaos has formed on the eastern slope - boulders of stone, sometimes reaching 3-5 m in diameter.
Ayu-Dag or Bear Mountain (Ukrainian Ayu-Dag, Crimean Catholicate. Ayuv Dağ, Ayuv Dag) is a mountain on the southern coast of Crimea, located on the border of Big Alushta and Big Yalta. The height of the mountain is 577 meters above sea level. This is a classic example of a laccolith.
Kara-Dag (Ukrainian Kara-Dag, Crimean Catholicate. Qara dağ, Kаara dag) is a mountain-volcanic massif, Crimea. Maximum height - 577 m (Mount Holy). It is a heavily destroyed volcanic form with a dome-shaped top.
Mashuk is a remnant magmatic mountain (laccolith mountain) in the central part of Pyatigorye on the Caucasian Mineral Waters, in the northeastern part of the city of Pyatigorsk. The height is 993.7 m. The peak has a regular dome shape.

Plateau-shaped mountain peaks

Mountain peaks that are flat in shape are called plateau-shaped.

Front Range Front Range) is a mountain range in the southern part of the Rocky Mountains in the United States, adjacent to the Great Plains on the west. The ridge stretches from south to north for 274 km. The highest point is Mount Grays Peak (4349 m). The ridge is composed mainly of granites. The peaks are plateau-shaped, the eastern slopes are gentle, the western slopes are steep.
Khibiny (Kild. Umptek) is the largest mountain range on the Kola Peninsula. Geological age is about 350 million years. The peaks are plateau-shaped, the slopes are steep with isolated snowfields. However, not a single glacier was discovered in the Khibiny Mountains. The highest point is Mount Yudychvumchorr (1200.6 m above sea level).
Amba (translated from Amharic as Mountain Fortress) is the name of the flat-topped hills and mesas in Ethiopia. They consist mainly of horizontal sandstones and layers of basalt. This determines the flat-topped shape of the mountains. Ambas are located at an altitude of up to 4,500 m.

Mountains by age

By age, mountains are divided into:

Young mountains,
Old (ancient) mountains.

Young mountains formed over the last 50 million years. In these mountain systems, internal processes are very actively developing, accompanied by the formation of mountains, earthquakes, and sometimes even volcanic activity. The youngest mountains on Earth are those belonging to the continental and island rings of the Pacific Ocean. The Caucasus Mountains are recognized as the youngest mountains in Russia. Here is the highest mountain in Russia - Elbrus (5642 m). (In the picture on the left: The Himalayas are young mountains, geological age about 38 million years)

Features of the young mountains:

the process of growth of young mountains is still ongoing,
the relief is sharp, highly dissected,
the peaks of the ridges are sharp,
the mountain slopes are steep and high,
high absolute altitudes,
significant height amplitude,
the valleys of numerous rivers are presented in the form of gorges, gorges,
Young mountains are characterized by the development of glaciers.

Examples of young mountains are:

Alps,
Caucasus Mountains,
Carpathians,
Kopet-Dag,
Pamir,
Mountains of Kamchatka.

Old (ancient) mountains are several hundred million years old. They differ in that the internal processes in them have long since died down, while the external processes that influence the destruction of the mountains are still active. This will continue until the relief is completely leveled. On many modern plains there are areas where, by all indications, there were once ancient mountains. From these mountains, only roots remained in the depths, covered with a thick layer of sedimentary rocks.

Features of old (ancient) mountains:

were heavily damaged,
have less contrasting relief,
the elevation differences are small,
gentle slopes,
The river valleys are well developed.

Examples of old (ancient) mountains are:

Ural mountains,
Timan,
Yenisei Ridge,
Khibiny (Kola Peninsula, geological age approximately 350 million years).

By origin

Tectonic mountains are formed as a result of the collision of moving sections of the earth's crust - lithospheric plates. This collision causes folds to form on the surface of the earth. This is how folded mountains arise. When interacting with air, water and under the influence of glaciers, the rock layers that form folded mountains lose their plasticity, which leads to the formation of cracks and faults. Currently, folded mountains have been preserved in their original form only in certain parts of the young mountains - the Himalayas, formed during the era of Alpine folding.

With repeated movements of the earth's crust, hardened folds of rock are broken into large blocks, which, under the influence of tectonic forces, rise or fall. This is how folded block mountains arise. This type of mountains is typical for old (ancient) mountains. An example is the Altai mountains. The emergence of these mountains occurred during the Baikal and Caledonian eras of mountain building; in the Hercynian and Mesozoic eras they were subject to repeated movements of the earth's crust. The type of folded-block mountains was finally adopted during the Alpine folding.

Volcanic mountains are formed during the process of volcanic eruptions. They are usually located along fault lines in the earth's crust or at the boundaries of lithospheric plates.

There are two types of volcanic mountains:

Volcanic cones. These mountains acquired their cone-shaped appearance as a result of the eruption of magma through long cylindrical vents. This type of mountain is widespread throughout the world. These are Fuji in Japan, Mount Mayon in the Philippines, Popocatepetl in Mexico, Misti in Peru, Shasta in California, etc.
Shield volcanoes. Formed by repeated outpouring of lava. They differ from volcanic cones in their asymmetrical shape and small size.

In areas of the globe where active volcanic activity occurs, entire chains of volcanoes can form. The most famous is the chain of Hawaiian Islands of volcanic origin, more than 1600 km long. These islands are the tops of underwater volcanoes, whose height from the surface of the ocean floor is more than 5500 meters.

Erosion (denudation) mountains

Erosion mountains arose as a result of the intensive dissection of stratified plains, plateaus and plateaus by flowing waters. Most mountains of this type are characterized by a table shape and the presence of box-shaped and sometimes canyon-type valleys between them. The last type of valley occurs most often when a lava plateau is dissected.

Examples of erosional (denudation) mountains are the mountains of the Central Siberian Plateau (Vilyuisky, Tungussky, Ilimsky, etc.). Most often, erosion mountains can be found not in the form of separate mountain systems, but within mountain ranges, where they are formed by the dissection of rock layers by mountain rivers.

By geographical location

On this basis, it is customary to group mountains into mountain systems, ridges, mountain ranges and single mountains.

Mountain belts are the largest formations. There are the Alpine-Himalayan mountain belt, stretching across Europe and Asia, and the Andean-Cordilleran mountain belt, passing through North and South America.

Mountainous country - many mountain systems.

Mountain system - mountain ranges and groups of mountains that are similar in origin and have the same age (for example, the Appalachians)

Mountain ranges are interconnected mountains stretched out in a line. For example, the Sangre de Cristo Mountains (North America).

Mountain groups are also mountains connected to each other, but not elongated in a line, but forming a group of indefinite shape. For example, Mount Henry in Utah and Bear Paw in Montana.

Solitary mountains are mountains that are not connected to other mountains, often of volcanic origin. For example, Mount Hood in Oregon and Rainier in Washington.

Mountains occupy about 24% of all land. The most mountains are in Asia - 64%, the least in Africa - 3%. 10% of the world's population lives in the mountains. And it is in the mountains that most rivers on our planet originate.

Characteristics of mountains

According to their geographical location, mountains are united into various communities that should be distinguished.

. Mountain belts- the largest formations, often stretching across several continents. For example, the Alpine-Himalayan belt passes through Europe and Asia or the Andean-Cordilleran belt, stretching through North and South America.
. Mountain system- groups of mountains and ranges similar in structure and age. For example, the Ural Mountains.

. Mountain ranges- a group of mountains stretched in a line (Sangre de Cristo in the USA).

. Mountain groups- also a group of mountains, but not stretched out in a line, but simply located nearby. For example, the Bear Pau Mountains in Montana.

. Single mountains- unrelated to others, often of volcanic origin (Table Mountain in South Africa).

Natural mountain areas

Natural zones in the mountains are arranged in layers and change depending on the height. At the foothills there is most often a zone of meadows (in the highlands) and forests (in the middle and low mountains). The higher you go, the harsher the climate becomes.

The change of zones is influenced by climate, altitude, mountain topography and their geographical location. For example, the continental mountains do not have a belt of forests. From the base to the summit, the natural areas vary from deserts to grasslands.

Types of mountains

There are several classifications of mountains according to various criteria: structure, shape, origin, age, geographical location. Let's look at the most basic types:

1. By age old and young mountains are distinguished.

Old are called mountain systems whose age is estimated at hundreds of millions of years. Internal processes in them have calmed down, but external processes (wind, water) continue to destroy, gradually comparing them with the plains. The old mountains include the Ural, Scandinavian, and Khibiny mountains (on the Kola Peninsula).

2. Height There are low mountains, middle mountains and high mountains.

Low mountains (up to 800 m) - with rounded or flat tops and gentle slopes. There are many rivers in such mountains. Examples: Northern Urals, Khibiny Mountains, spurs of the Tien Shan.

Average mountains (800-3000 m). They are characterized by a change in landscape depending on the height. These are the Polar Urals, the Appalachians, the mountains of the Far East.

High mountains (over 3000 m). These are mostly young mountains with steep slopes and sharp peaks. Natural areas change from forests to icy deserts. Examples: Pamirs, Caucasus, Andes, Himalayas, Alps, Rocky Mountains.

3. By origin There are volcanic (Fujiyama), tectonic (Altai mountains) and denudation, or erosion (Vilyuisky, Ilimsky).

4. According to the shape of the top mountains can be peak-shaped (Communism Peak, Kazbek), plateau-shaped and table-shaped (Amba in Ethiopia or Monument Valley in the USA), domed (Ayu-Dag, Mashuk).

Climate in the mountains

The mountain climate has a number of characteristic features that appear with altitude.

Decrease in temperature - the higher it is, the colder it is. It is no coincidence that the peaks of the highest mountains are covered with glaciers.

Atmospheric pressure decreases. For example, at the top of Everest the pressure is two times lower than at sea level. This is why water boils faster in the mountains - at 86-90ºC.

The intensity of solar radiation increases. In the mountains, sunlight contains more ultraviolet radiation.

The amount of precipitation is increasing.

High mountain ranges trap precipitation and influence the movement of cyclones. Therefore, the climate on different slopes of the same mountain may differ. On the windward side there is a lot of moisture and sun, on the leeward side it is always dry and cool. A striking example is the Alps, where on one side of the slopes there are subtropics, and on the other, a temperate climate prevails.

The highest mountains in the world

(Click on the picture to enlarge the diagram in full size)

There are seven highest peaks in the world that all climbers dream of conquering. Those who succeed become honorary members of the Seven Peaks Club. These are mountains such as:

. Chomolungma, or Everest (8848 m). Located on the border of Nepal and Tibet. Belongs to the Himalaya mountain system. It has the shape of a triangular pyramid. The first conquest of the mountain took place in 1953.

. Aconcagua(6962 m). It is the highest mountain in the southern hemisphere, located in Argentina. Belongs to the Andes mountain system. The first ascent took place in 1897.

. McKinley- the highest peak in North America (6168 m). Located in Alaska. First conquered in 1913. It was considered the highest point in Russia until Alaska was sold to America.

. Kilimanjaro- the highest point in Africa (5891.8 m). Located in Tanzania. First conquered in 1889. This is the only mountain where all types of Earth's belts are represented.

. Elbrus- the highest peak in Europe and Russia (5642 m). Located in the Caucasus. The first ascent took place in 1829.

. Vinson Massif- the highest mountain in Antarctica (4897 m). Part of the Ellsworth Mountains system. First conquered in 1966.

. Mont Blanc- the highest point in Europe (many attribute Elbrus to Asia). Height - 4810 m. Located on the border of France and Italy, it belongs to the Alps mountain system. The first ascent in 1786, and a century later, in 1886, Theodore Roosevelt conquered the top of Mont Blanc.

. Pyramid of Carstens- the highest mountain in Australia and Oceania (4884 m). Located on the island of New Guinea. The first conquest was in 1962.

Mountains are different: old and young, rocky and flat, domed and peaked. Some of them are covered with dense forests, others with lifeless stone deposits. But in this article we will talk about their height. Which mountains are medium and which are considered high?

Mountain as a landform

First of all, it is worth answering the question of whether this is a positive form of relief, characterized by a sharp and isolated elevation of the terrain. In any mountain, three main elements are clearly visible:

vertex;
foot;
slope.

Any mountain system on the planet is nothing more than a complex system of valleys (depressions) and ridges, consisting of dozens of individual peaks. All of them are external manifestations of the internal (endogenous) forces of the Earth - tectonic movements of the earth's crust and volcanism.

Mountains create the most beautiful and unique landscapes on the surface of our planet. They are distinguished by their unique soil cover, unique flora and fauna. But people settle in the mountains extremely reluctantly. According to statistics, about 50% of the earth's population lives at altitudes not exceeding 200 meters above sea level.

Classification of mountains in geomorphology. Mountains are medium, low and high

In geomorphological science, mountains are usually classified according to a number of characteristics: age, height, geographical location, genesis, shape of peaks, etc.

By their origin they can be tectonic, denudation or volcanic, and by age - old or young. Moreover, a mountain system whose formation time does not exceed 50 million years is considered young. By geological standards, this is a very small age.

Depending on the shape of their peak, mountains are:

peaked;
domed;
plateau-shaped (“table”).

Geographers distinguish mountains based on their altitude above sea level:

low;
average;
tall.

Sometimes in the literature you can find intermediate altitude types, for example, medium-high or medium-low mountains. It is immediately worth noting that mountains of medium height can be found in any part of the world. However, most of them are in Europe and Asia.

Middle Mountains: examples and height

8848 meters - this is the height reached by the highest peak in the world - Chomolungma, or Everest. The absolute height of the middle mountains is much more modest: from 1 to 3 km above sea level.

The most famous examples of such mountain systems are the Carpathians, Appalachians, Tatras, Apennines, Pyrenees, Scandinavian and Drakensberg Mountains, Australian Alps, Stara Planina. There are medium mountains also within Russia. These are the Ural Mountains, Eastern Sayan, Sikhote-Alin (pictured below) and others.

An important feature of the middle mountains is the presence of altitudinal zones. That is, the vegetation and landscapes here change with altitude.

Carpathians

The Carpathians are the largest mountain system in Europe, spanning eight countries. Linguists, explaining the origin of its name, came to the conclusion that this toponym has Proto-Indo-European roots and is translated as “stone”, “rock”.

The Carpathians stretch in an arc of one and a half thousand kilometers, from the Czech Republic to Serbia. And the highest point of this mountain system is located on the territory of Slovakia (Mount Gerlachovsky Štit, 2654 m). An interesting fact: between the Alps and the extreme eastern spurs of the Carpathians there are only 15 kilometers.

The Carpathians are young mountains. They formed in the Cenozoic. However, their outlines are smooth and gentle, which is more typical of older geological structures. This can be explained by the fact that the Carpathians are predominantly composed of soft rocks (chalk, limestone and clay).

The mountain system is divided into three conventional parts: Western, Eastern (or Ukrainian) and Southern Carpathians. It also includes the Transylvanian Plateau. are characterized by fairly high seismicity. Here is the so-called Vrancea zone, which “produces” earthquakes with a magnitude of 7-8.

Appalachia

Geomorphologists often call the Appalachians the identical twin of the Carpathians. In appearance they are not much different from each other. The Appalachian Mountains are located in the eastern part of North America, within two states (USA and Canada). They stretch from to the Gulf of Mexico in the south. The total length of the mountain system is about 2500 kilometers.

If the European Carpathians are young mountains, then the American Appalachians are a product of earlier Hercynian and Caledonian folds. They formed about 200-400 million years ago.

The Appalachian Mountains are rich in a variety of mineral resources. Coal, asbestos, oil, and iron ore are mined here. In this regard, this mountainous region is also very often called the historical “industrial belt” of the United States.

Australian Alps

It turns out that the Alps are not only in Europe. Residents of the smallest and driest continent can also go hiking in the real Alps. But only in Australia!

This mountain system is located in the southern part of the continent. It is here that the highest point in all of Australia is located - Mount Kosciuszko (2228 m). And on the slopes of these mountains, the longest river of the mainland, the Murray, originates.

The Australian Alps are stunningly diverse in landscape terms. In these mountains you can find snow-capped peaks, deep green valleys, and lakes with clear water. The mountain slopes are decorated with bizarre-looking rocks. The Australian Alps are home to several picturesque national parks and excellent ski resorts.

Finally

Now you know which mountains are medium and which are high. Geomorphologists distinguish three types of mountain systems based on height. The middle mountains have an altitude of 1000 to 3000 meters above sea level. The Carpathians, Appalachians, and Australian Alps are the most striking examples of such mountain systems in the world.

Mountains- strongly dissected parts of land, significantly, by 500 meters or more, elevated above the adjacent plains.

The main feature by which mountains are classified is the height of the mountains. So, according to the height of the mountains there are:

Lowlands (low mountains)– mountain heights up to 800 meters above sea level.

Features of low mountains:

The tops of the mountains are round, flat,

· The slopes are gentle, not steep, covered with forest,

· Characteristically, there are river valleys between the mountains.

Examples: Northern Urals, spurs of the Tien Shan, some ridges of Transcaucasia, Khibiny Mountains on the Kola Peninsula, individual mountains of Central Europe.

Medium mountains (medium or mid-altitude mountains)– the height of these mountains is from 800 to 3000 meters above sea level.

Features of the middle mountains: Medium-altitude mountains are characterized by altitudinal zonation, i.e. change of landscape with change in altitude.

Examples of medium mountains: The mountains of the Middle Urals, the Polar Urals, the mountains of the island of Novaya Zemlya, the mountains of Siberia and the Far East, the mountains of the Apennine and Iberian Peninsulas, the Scandinavian mountains in northern Europe, the Appalachians in North America, etc.

Highlands (high mountains)– the height of these mountains is more than 3000 meters above sea level. These are young mountains, the relief of which is intensively formed under the influence of external and internal processes.

Features of the highlands:

· Mountain slopes are steep, high,

· The peaks of the mountains are sharp, peak-shaped, have a specific name - “Carlings”,

The mountain ridges are narrow, jagged,

· Characterized by altitudinal zones from forests at the foot of the mountains to icy deserts at the tops.

Examples of highlands: Pamir, Tien Shan, Caucasus, Himalayas, Cordillera, Andes, Alps, Karakorum, Rocky Mountains, etc.

The next characteristic by which mountains are classified is their origin. So, according to the origin of mountains, there are tectonic, volcanic and erosional (denudation):

Tectonic mountains are formed as a result of the collision of moving parts of the earth's crust - lithospheric plates. This collision causes folds to form on the surface of the earth. This is how they arise fold mountains. When interacting with air, water and under the influence of glaciers, the rock layers that form folded mountains lose their plasticity, which leads to the formation of cracks and faults. Currently, folded mountains have been preserved in their original form only in certain parts of the young mountains - the Himalayas, formed during the era of Alpine folding.

With repeated movements of the earth's crust, hardened folds of rock are broken into large blocks, which, under the influence of tectonic forces, rise or fall. This is how they arise fold-block mountains. This type of mountains is typical for old (ancient) mountains. An example is the Altai mountains. The emergence of these mountains occurred during the Baikal and Caledonian eras of mountain building; in the Hercynian and Mesozoic eras they were subject to repeated movements of the earth's crust. The type of folded-block mountains was finally adopted during the Alpine folding.

Volcanic mountains formed during volcanic eruptions. They are usually located along fault lines in the earth's crust or at the boundaries of lithospheric plates.

Volcanic there are mountains two types:

Volcanic cones. These mountains acquired their cone-shaped appearance as a result of the eruption of magma through long cylindrical vents. This type of mountain is widespread throughout the world. These are Fuji in Japan, Mount Mayon in the Philippines, Popocatepetl in Mexico, Misti in Peru, Shasta in California, etc.
Shield volcanoes. Formed by repeated outpouring of lava. They differ from volcanic cones in their asymmetrical shape and small size.

Erosion (denudation) mountains.

What types of mountains are there?

There were times when mountains were considered a mysterious and dangerous place. However, many of the mysteries associated with the appearance of mountains have been unraveled in the last two decades thanks to the revolutionary theory of lithospheric plate tectonics. Mountains are elevated areas of the earth's surface that rise steeply above the surrounding area.

Peaks in the mountains, unlike plateaus, occupy a small area. Mountains can be classified according to different criteria:

Geographical location and age, taking into account their morphology;

Features of the structure, taking into account the geological structure.

In the first case, mountains are divided into mountain systems, cordilleras, single mountains, groups, chains, and ridges.

The name Cordillera comes from a Spanish word that means "chain". Cordilleras include groups of mountains, ranges and mountain systems of different ages. In western North America, the Cordillera region includes the Coast Ranges, Sierra Nevada, Cascade Mountains, Rocky Mountains, and many small ranges between the Sierra Nevada of Nevada and Utah and the Rocky Mountains.

The cordilleras of Central Asia (you can read more about this part of the world in this article) include, for example, the Tien Shan, Kanlun and the Himalayas. Mountain systems consist of groups of mountains and ranges that are similar in origin and age (the Appalachians, for example). The ridges consist of mountains that stretch in a long, narrow strip. Single mountains, usually of volcanic origin, are found in many areas of the globe.

The second classification of mountains is compiled taking into account endogenous processes of relief formation.

VOLCANIC MOUNTAINS.

Volcanic cones are common in almost all areas of the globe. They are formed by accumulations of rock fragments and lava erupted through vents by forces that operate deep within the Earth.Illustrative examples of volcanic cones are Shasta in California, Fuji in Japan, Mayon in the Philippines, and Popocatepetl in Mexico.Ash cones have a similar structure, but they consist mainly of volcanic scoria, and they are not so tall. Such cones exist in northeastern New Mexico and near Lassen Peak.Shield volcanoes form during repeated lava eruptions. They are somewhat not as tall and they do not have such a symmetrical structure as volcanic cones.

There are many shield volcanoes in the Aleutian and Hawaiian Islands. Chains of volcanoes occur in long narrow strips. Where the plates that lie along the ridges stretching along the ocean floor diverge, magma, trying to fill the crevice, rises upward, eventually forming new crystalline rock.Sometimes magma accumulates on the seabed - thus, underwater volcanoes appear, and their peaks rise above the surface of the water like islands.

If two plates collide, one of them lifts the second, and the latter, being pulled deep into the oceanic basin, melts into magma, part of which is pushed to the surface, creating chains of islands of volcanic origin: for example, Indonesia, Japan, and the Philippines arose this way.

The most popular chain of such islands is the Hawaiian Islands, 1600 km long. These islands were formed by the northwestward movement of the Pacific plate over a crustal hot spot. A crustal hot spot is a place where a hot mantle flow rises to the surface and melts the oceanic crust moving above it. If you count from the surface of the ocean, where the depth is about 5500 m, then some of the peaks of the Hawaiian Islands will be among the highest mountains in the world.

FOLDED MOUNTAINS.

Most experts today believe that the cause of folding is the pressure that occurs during the drift of tectonic plates. The plates on which the continents rest move only a few centimeters a year, but their convergence causes the rocks on the edges of these plates and the layers of sediment on the ocean floor that separate the continents to gradually rise up in the ridges of mountain ranges.Heat and pressure are formed during the movement of plates, and under their influence some layers of rock are deformed, lose strength and, like plastic, bend into giant folds, while others, stronger or not so heated, break and are often torn off from their base.

During the mountain building stage, heat also causes magma to appear near the layer that underlies the continental portions of the earth's crust. Huge areas of magma rise and solidify to form the granite core of the folded mountains.Evidence of past collisions of continents is the old folded mountains that stopped growing long ago, but have not yet collapsed.For example, in the east of Greenland, in the northeast of North America, in Sweden, in Norway, in the west of Scotland and Ireland, they appeared at a time when Europe and North America (for more information about this continent, see this article) converged and became one huge continent.

This huge mountain chain, due to the formation of the Atlantic Ocean, was torn apart later, about 100 million years ago. At first, many large mountain systems were folded, but during further development their structure became significantly more complex.Zones of initial folding are limited by geosynclinal belts - huge troughs in which sediments accumulated, mainly in shallow oceanic formations.Often folds are visible in mountainous areas on exposed cliffs, but not only there. Synclinals (troughs) and anticlines (saddles) are the simplest of folds. Some folds are overturned (recumbent).Others are displaced relative to their base so that the upper parts of the folds move out - sometimes by several kilometers, and they are called nappes.

BLOCK MOUNTAINS.

Many large mountain ranges were formed as a result of tectonic uplift that occurred along faults in the earth's crust. The Sierra Nevada Mountains in California are a huge horst about 640 km long and 80 to 120 km wide.The eastern edge of this horst has been raised the highest, where Mount Whitney reaches 418 m above sea level.Much of the modern appearance of the Appalachians was the result of several processes: the original folded mountains were subject to denudation and erosion, and then rose along faults.The Great Basin contains a series of block mountains between the Sierra Nevada Mountains to the west and the Rocky Mountains to the east.Long narrow valleys lie between the ridges; they are partially filled with sediments brought from adjacent blocky mountains.

DOME-SHAPED MOUNTAINS.

domed mountainsIn many areas, land areas that have undergone tectonic uplift have taken on a mountainous appearance under the influence of erosion processes. In those areas where the uplift occurred over a relatively small area and was of a dome-like nature, dome-shaped mountains formed. The Black Hills are a prime example of such mountains, which are about 160 km across.The area was subject to dome uplift and much of the sedimentary cover was removed by further denudation and erosion.The central core was exposed as a result. It consists of metamorphic and igneous rocks. It is surrounded by ridges that consist of more resistant sedimentary rocks.

REMAINING PLATEAUS.

remnant plateaus Due to the action of erosion-denudation processes, a mountain landscape is formed on the site of any elevated territory. Its appearance depends on its original height. When a high plateau like Colorado, for example, was destroyed, a highly dissected mountainous terrain was formed.The Colorado Plateau, hundreds of kilometers wide, was raised to a height of about 3000 m. Erosion-denudation processes have not yet had time to completely transform it into a mountain landscape, but within some large canyons, for example the Grand Canyon of the river. Colorado, mountains several hundred meters high arose.These are erosional remains that have not yet been denuded. With the further development of erosion processes, the plateau will acquire an increasingly pronounced mountain appearance.In the absence of repeated uplift, any territory will eventually be leveled and turn into a plain.