Landform classifications
There are several classifications of landforms of the Earth, which have different bases. According to one of them, two groups of landforms are distinguished:
- positive - convex in relation to the plane of the horizon (continents, mountains, hills, hills, etc.);
- negative - concave (oceans, basins, river valleys, ravines, beams, etc.).
The classification of the forms of the Earth's relief by size is presented in Table. 1 and in fig. 1.
Table 1. Landforms of the Earth by size
Rice. 1. Classification of the largest landforms
We will separately consider the relief forms characteristic of the land and the bottom of the World Ocean.
The relief of the Earth on the map of the World
Ocean floor landforms
The bottom of the World Ocean is divided by depth into the following components: continental shelf (shelf), continental (coastal) slope, bed, deep-water (abyssal) basins (troughs) (Fig. 2).
continental shelf- the coastal part of the seas and lying between the coast and the continental slope. This former coastal plain in the topography of the ocean floor is expressed as a shallow, slightly hilly plain. Its formation is mainly associated with the subsidence of individual land areas. This is confirmed by the presence of underwater valleys, coastal terraces, fossil ice, permafrost, remnants of terrestrial organisms, etc. within the continental shallows. The continental shallows are usually distinguished by a slight bottom slope, which is practically horizontal. On average, they drop from 0 to 200 m, but depths of more than 500 m can occur within their limits. The relief of the continental shoal is closely related to the relief of the adjacent land. On mountainous coasts, as a rule, the continental shelf is narrow, and on flat coasts it is wide. The continental shelf reaches its greatest width off the coast of North America - 1400 km, in the Barents and South China Seas - 1200-1300 km. Typically, the shelf is covered with clastic rocks brought by rivers from land or formed during the destruction of the coast.
Rice. 2. Landforms of the ocean floor
Continental slope - the inclined surface of the bottom of the seas and oceans, connecting the outer edge of the continental shoal with the ocean floor, extending to a depth of 2-3 thousand m. It has rather large angles of inclination (on average 4-7 °). The average width of the continental slope is 65 km. Off the coast of coral and volcanic islands, these angles reach 20-40°, and near the coral islands there are angles of greater magnitude, almost vertical slopes - cliffs. Steep continental slopes lead to the fact that in the areas of maximum inclination of the bottom, masses of loose sediments slide down to the depths under the action of gravity. In these areas, a bare sloping bottom can be found.
The relief of the continental slope is complex. Often the bottom of the continental slope is indented by narrow deep canyon gorges. They often visit steep rocky shores. But there are no canyons on continental slopes with a gentle slope of the bottom, and also where there are islands or underwater reefs on the outer side of the continental shelf. The tops of many canyons adjoin the mouths of existing or ancient rivers. Therefore, canyons are considered as an underwater continuation of flooded riverbeds.
Another characteristic element of the relief of the continental slope are underwater terraces. These are the underwater terraces of the Sea of Japan, located at a depth of 700 to 1200 m.
Ocean bed- the main expanse of the bottom of the World Ocean with prevailing depths of more than 3000 m, extending from the underwater margin of the mainland into the depths of the ocean. The area of the ocean floor is about 255 million km 2, i.e., more than 50% of the bottom of the World Ocean. The bed is distinguished by insignificant angles of inclination, on average they are 20-40 °.
The relief of the ocean floor is no less complex than that of the land. The most important elements of its relief are abyssal plains, oceanic basins, deep-sea ridges, mid-ocean ridges, uplands and underwater plateaus.
In the central parts of the oceans are located mid-ocean ridges, rising to a height of 1-2 km and forming a continuous ring of uplifts in the Southern Hemisphere at 40-60 ° S. sh. Three ridges extend northward from it, extending meridianally, in each ocean: the Mid-Atlantic, Mid-Indian and East Pacific. The total length of the Middle Oceanic Ranges is more than 60,000 km.
Between the mid-ocean ridges are deep-sea (abyssal) plains.
abyssal plains- smooth surfaces of the bottom of the World Ocean, which lie at depths of 2.5-5.5 km. It is the abyssal plains that occupy approximately 40% of the ocean floor area. Some of them are flat, others are wavy with a height amplitude of up to 1000 m. One plain is separated from the other by ridges.
Some of the solitary mountains located on the abyssal plains protrude above the surface of the water in the form of islands. Most of these mountains are extinct or active volcanoes.
Strings of volcanic islands above a subduction zone, where one oceanic plate subducts under another, are called island arcs.
In shallow waters in tropical seas (mainly in the Pacific and Indian Oceans), coral reefs are formed - calcareous geological structures formed by colonial coral polyps and some types of algae that can extract lime from sea water.
About 2% of the ocean floor is deep-water (over 6000m) depressions - gutters. They are located where the oceanic crust subducts under the continents. These are the deepest parts of the oceans. More than 22 deep-sea basins are known, 17 of them are in the Pacific Ocean.
landforms
The main landforms on land are mountains and plains.
Mountains - isolated peaks, massifs, ridges (usually more than 500 m above sea level) of various origins.
In general, 24% of the earth's surface is covered by mountains.
Nai highest point mountains called mountain top. The highest mountain peak of the Earth is Mount Chomolungma - 8848 m.
Depending on the height, the mountains are low, medium, high and highest (Fig. 3).
Rice. 3. Classification of mountains by height
The highest mountains of our planet are the Himalayas, the Cordilleras, the Andes, the Caucasus, the Pamirs can serve as an example of high mountains, the Scandinavian Mountains and the Carpathians are medium, and the Ural Mountains are low.
In addition to the aforementioned mountains, the globe there are many others. You can get acquainted with them on the maps of the atlas.
According to the method of formation, the following types of mountains are distinguished:
- folded - formed as a result of crushing into folds of a thick layer of sedimentary rocks (mainly formed in the Alpine era of mountain building, therefore they are called young mountains) (Fig. 4);
- blocky - formed as a result of raising rigid blocks to a great height earth's crust; characteristic of ancient platforms: the internal forces of the Earth split the rigid foundation of the platforms into separate blocks and raise them to a considerable height; as a rule, ancient or revived) (Fig. 5);
- folded-blocky - these are old folded mountains that have largely collapsed, and then, in new periods of mountain building, their individual blocks were again raised to a great height (Fig. 6).
Rice. 4. Formation of folded mountains
Rice. 5. Formation of old (blocky) mountains
According to the location, epigeosynclinal and epiplatform mountains are distinguished.
By origin, mountains are divided into tectonic, erosional, volcanic.
Rice. 6. Formation of fold-block renewed mountains
tectonic mountains- these are mountains that were formed as a result of complex tectonic disturbances of the earth's crust (folds, thrusts and various kinds of faults).
Erosive mountains - high plateau-like areas of the earth's surface with a horizontal geological structure, strongly and deeply dissected by erosion valleys.
Volcanic mountains - these are volcanic cones, lava flows and tuff covers, distributed over a large area and usually superimposed on a tectonic base (on a young mountainous country or on ancient platform structures, such as volcanoes in Africa). Volcanic cones formed by accumulations of lava and rock fragments erupted through long cylindrical vents. These are the Maoin mountains in the Philippines, Mount Fuji in Japan, Popocatepetl in Mexico, Misty in Peru, Shasta in California, etc. Thermal cones have a structure similar to volcanic cones, but are not so high and are composed mainly of volcanic slag - a porous volcanic rock that looks like ash.
Depending on the areas occupied by mountains, their structure and age, mountain belts, mountain systems, mountainous countries, mountain prices, mountain ranges and uplifts of a smaller rank are distinguished.
mountain range called a linearly elongated positive landform, formed by large folds and having a significant length, mostly in the form of a single watershed line, along which the most
significant heights, with clearly defined ridges and slopes facing in opposite directions.
Mountain chain- a long mountain range, elongated in the direction of the general strike of the folds and separated from adjacent parallel chains by longitudinal valleys.
mountain system- formed during one geotectonic epoch and having spatial unity and a similar structure, a set of mountain ranges, chains, highlands(large area of mountain uplifts, which are a combination of high plains, mountain ranges and massifs, sometimes alternating with wide intermountain basins) and intermountain depressions.
Mountain country- a set of mountain systems formed in one geotectonic epoch, but having a different structure and appearance.
mountain belt- the largest unit in the classification of mountain relief, corresponding to the largest mountain structures, combined spatially and according to the history of development. Usually the mountain belt stretches for many thousands of kilometers. An example is the Alpine-Himalayan mountain belt.
Plain- one of the most important elements of the relief of the land surface, the bottom of the seas and oceans, characterized by small fluctuations in heights and slight slopes.
The scheme of formation of plains is shown in fig. 7.
Rice. 7. Formation of plains
Depending on the height, among the land plains, there are:
- lowlands - having an absolute height from 0 to 200 m;
- elevations - not higher than 500 m;
- plateaus.
Plateau- a vast area of relief with a height of 500 to 1000 m or more, with a predominance of flat or slightly undulating watershed surfaces, sometimes separated by narrow, deeply incised valleys.
The surface of the plains can be horizontal and inclined. Depending on the nature of the mesorelief that complicates the surface of the plain, flat, stepped, terraced, undulating, ridged, hilly, hilly, and other plains are distinguished.
According to the principle of the predominance of existing exogenous processes, the plains are divided into denudation, formed as a result of the destruction and demolition of previously existing uneven terrain, and accumulative resulting from the accumulation of loose sediments.
Denudation plains, the surface of which is close to the structural surfaces of a slightly disturbed cover, are called reservoir.
Accumulative plains are usually subdivided into volcanic, marine, alluvial, lacustrine, glacial, etc. Accumulative plains of complex origin are also widespread: lacustrine-alluvial, delta-marine, alluvial-proluvial.
The general features of the relief of the planet Earth are the following:
Land occupies only 29% of the Earth's surface, which is 149 million km2. The bulk of the land mass is concentrated in the Northern Hemisphere.
The average land height of the Earth is 970 m.
On land, plains and low mountains up to 1000 m high prevail. Mountain elevations above 4000 m occupy an insignificant area.
The average depth of the ocean is 3704 m. The relief of the bottom of the World Ocean is dominated by plains. The share of deep-sea depressions and trenches accounts for only about 1.5% of the ocean area.
As we already know, the earth's crust is mobile.
And this movement is determined by the movement of the substance of the mantle. As a result of such movement, mountains, oceanic depressions, and island arcs arise in the most mobile parts of the earth's crust. For stable areas of the earth's crust, flat surfaces are characteristic. All this we call the relief of the Earth.
Continents and oceans- basic, most large forms relief of the Earth. Their formation is due to tectonic, cosmic and planetary processes.
The mainland (continent) is the largest massif of the earth's crust, which has a three-layer structure: a sedimentary layer, a "granite" layer and a "basalt" layer. The average thickness of the continental crust is 35-45 km. Most of the surface of the mainland protrudes above the level of the oceans. In the modern geological era, there are six continents: Eurasia, Africa, North America, South America, Australia, Antarctica.
The World Ocean is a continuous body of water surrounding the continents. The world ocean is divided by continents into four oceans: Pacific, Atlantic, Indian and Arctic. The share of land accounts for only 29% of the Earth's area. Everything else is the World Ocean.
Mountains and plains, as well as continents and oceans, are the main landforms of the Earth. Mountains are formed as a result of tectonic processes in zones of active tectonic activity, and plains - in areas that are little subject to mountain-forming processes.
Plains- large areas with a flat or hilly surface. They vary in height. An example of a lowland is the Amazonian lowland - the largest on Earth. It happens that the lowlands are located below sea level - these are depressions. The Caspian lowland is located 28 m below sea level. At an altitude of 200-500 m above sea level, there are uplands, for example, Central Russian, and above 500 m - plateaus. An example of such a plain is the Central Siberian Plateau.
Mountains- areas of the earth's surface elevated above sea level to a height of more than 500 m. Mountains are considered low if their height is from 500 to 1000 m; medium - from 1000 to 2000 m and high - over 2000 m. high mountain on Earth - Chomolungma (Everest) has a height of 8848 m. You can determine the height of the mountains by physical map using the height scale.
Mountains differ not only in height, but also in shape. A linearly elongated group of mountains is called a mountain range. The mountains of the Caucasus have this shape.
There are also mountain belts (Andean belt), mountain systems (the system of mountains of Southern Siberia) and mountainous countries. Pamir is an example of a mountainous country.
Mountains and plains are located both on the continents and in the oceans. Mid-ocean ridges are an example of mountains in the ocean.
landform- the result of the struggle of internal and external forces. The internal forces of the Earth form large landforms: continents and oceans, mountains and plains. They not only form them, but also change and destroy them. Outside forces work constantly and slowly. They also destroy mountain ranges, fill deep depressions, form hills, valleys, gullies, ravines, form riverbeds, i.e., form smaller landforms.
The destruction and change of rocks under the influence of fluctuations in air temperature, moisture and living organisms is called weathering.
Here are some examples of weathering. In the mountains, these are landslides, landslides, mudflows, rockfalls, deep gorges cut by mountain rivers, and moraine deposits of glaciers. For the plains typical examples weathering are ravines, river valleys.
The "calm" life of the Earth's stone shell ends as soon as it comes into contact with water or gases. Then amazing transformations take place on the earth's surface and phenomena are observed that simply cannot arise in the deep bowels.
The relief of the Earth is a combination of various surface irregularities, both large and small, resulting from the activity of external and internal forces. An important role in the formation of relief is played by gravity, density and composition of rocks, activity and flowing waters. The formidable forces of nature, setting in motion the strongest rock massifs, both destroy them to the ground and create new mountains, gorges and valleys. Even on the vast plains appear, which eventually become covered with silt and large debris. It happens rather slowly, and human life not enough to notice surface changes. It seems to be breathing - it rises, then falls, waves run through it, it bursts from the stresses that have arisen.
On the surface of the planet, water circulates (from to land and further to), a change in vegetation cover and migration of animals, the movement of large debris and the smallest ache. Scientists consider all this to be a process of matter and energy exchange, which leads to the formation of loose sediments, and at the same time to the formation, i.e., to the process of morpholithogenesis. Even if a few grains of sand move a short distance or with water, a small hole or bump will appear on the surface. However, morpholithogenetic analysis reveals only a part of the relationships between the relief, atmosphere, and natural waters. The other part of the connections is shown by morphostructural analysis.
Morphostructures called the geological structures expressed in the modern relief. The largest morphostructures on Earth are. They belong to planetary morphostructures, within which there are mountain belts, plateaus and plains, underwater ridges and basins, differing in the structure of the earth's crust, type and speed, and the degree of participation of other factors in their formation. Thus, planetary morphostructures are composed of smaller regional morphostructures.
Relief large regions formed over many millions of years. On the sites of ancient platforms, a crystalline basement, composed of gneisses, granites, shales and sandstones, usually comes to the surface. Such a foundation serves as a base for the relief, a plinth, and those built by these rocks are called basement plains. In Russia, they can be found in, on, in the north of Siberia.
The analysis is used in the study of large landforms composed of various rocks; tectonic movements that caused the appearance of large landforms; discontinuous disturbances - faults that limit morphostructures.
If we talk about the age of the relief of large mountain belts, then it is obvious that their age is at least 200 million years; if we will talk, for example, about the age of the Caucasus Mountains, then it will be 80 - 90 million years. In both cases, to determine the age of the relief, it is necessary to know the beginning of the appearance of its largest and most characteristic forms. In mountainous areas, this is the formation of not only ridges, but also intermountain depressions. Often, to determine the time of the beginning of the division of the relief into hills and hills, mountains and depressions, the age of one of the ancient alignment surfaces is taken as the starting point of reference. This is the name of the wavy plain that existed in the past on many, slightly dissected by erosion.
The beginning of the division of the plain is the starting point for determining the age of the relief.
Relief age- the time that has elapsed since the formation of its modern appearance. It is measured in a single time - in years, hundreds, thousands, millions of years, although time ranges are often used, calling the relief Mesozoic, Neogene-Quaternary, Late Pleistocene, etc.
Formation of the Earth's relief
Features of the Earth's relief
Relief- a set of irregularities of the earth's surface.
The relief is composed of positive (convex) and negative (concave) forms. The largest negative forms relief on Earth - the depressions of the oceans, positive - continents. These are landforms of the first order. Landforms second order - mountains and plains (both on land and at the bottom of the oceans). The surface of mountains and plains has a complex relief, consisting of smaller forms.
Morphostructures- large elements of the relief of land, the bottom of the oceans and seas, the leading role in the formation of which belongs to endogenous processes . The largest irregularities on the Earth's surface form protrusions of the continents and depressions of the oceans. The largest land relief elements are flat-platform and mountainous areas.
Plain-platform areas include flat parts of ancient and young platforms and occupy about 64% of the land area. Among the flat-platform areas there are low , with absolute heights of 100-300 m (East European, West Siberian, Turan, North American plains), and high raised latest movements crust to a height of 400-1000 m (Central Siberian Plateau, African-Arabian, Hindustan, significant parts of the Australian and South American plains).
mountainous areas occupy about 36% of the land area.
Underwater margin of the mainland (about 14% of the Earth's surface) includes a shallow, flat, as a whole, continental shelf (shelf), a continental slope, and a continental foot located at depths from 2500 to 6000 m. The continental slope and the continental foot separate the protrusions of the continents, formed by the combination of land and shelf, from the main part of the ocean floor, called the ocean floor.
Island arc zone - transitional zone of the ocean bed. The actual ocean bed (about 40% of the Earth's surface) is mostly occupied by deep-water (average depth 3-4 thousand m) plains, which correspond to oceanic platforms.
Morphosculptures- elements of the relief of the earth's surface, in the formation of which the leading role belongs to exogenous processes . The work of rivers and temporary streams plays the greatest role in the formation of morphosculptures. They create widespread fluvial (erosion and accumulative) forms (river valleys, gullies, ravines, etc.). Glacial forms are widespread due to the activity of modern and ancient glaciers, especially the sheet type (northern part of Eurasia and North America). They are represented by valley-mitrogs, "ram's foreheads" and "curly" rocks, moraine ridges, eskers, etc. In the vast territories of Asia and North America, where permafrost rock strata are widespread, various forms of permafrost (cryogenic) relief are developed.
The most important landforms.
The largest landforms are the protrusions of the continents and the depressions of the oceans. Their distribution depends on the presence of a granite layer in the earth's crust.
The main landforms of land are mountains And plains . Approximately 60% of the land is occupied plains- vast areas of the earth's surface with relatively small (up to 200 m) elevation fluctuations. According to the absolute height, the plains are divided into lowlands (height 0-200 m), hills (200-500 m) and plateaus (above 500 m). By the nature of the surface - flat, hilly, stepped.
Table “Relief and landforms. Plains.
Mountains- elevations of the earth's surface (more than 200 m) with clearly defined slopes, soles, peaks. In appearance, the mountains are divided into mountain ranges, chains, ridges and mountainous countries. Separate mountains are rare, representing either volcanoes or the remains of ancient destroyed mountains. Morphological mountain elements are: base (sole); slopes; peak or ridge (near ridges).
sole of the mountain- this is the border between its slopes and the surrounding area, and it is expressed quite clearly. With a gradual transition from the plains to the mountains, a strip is distinguished, which is called the foothills.
slopes occupy most of the surface of the mountains and are extremely diverse in appearance and steepness.
Vertex- the highest point of the mountain (mountain ranges), the pointed peak of the mountain - the peak.
Mountain countries(mountain systems) - large mountain structures, which consist of mountain ranges - linearly elongated mountain uplifts intersecting with slopes. The points of connection and intersection of mountain ranges form mountain nodes. These are usually the highest parts of mountainous countries. The depression between two ridges is called a mountain valley.
uplands- sections of mountainous countries, consisting of heavily destroyed ridges and high plains covered with destruction products.
Table “Relief and landforms. Mountains"
Mountains are divided into low (up to 1000 m), medium-high (1000-2000 m), high (more than 2000 m). According to the structure, folded, folded-block and blocky mountains are distinguished. By geomorphological age, young, rejuvenated and revived mountains are distinguished. On land, mountains of tectonic origin predominate, in the oceans - volcanic.
Volcano(from Latin vulcanus - fire, flame) - a geological formation that occurs above channels and cracks in the earth's crust, through which lava, ash, combustible gases, water vapor and rock fragments erupt onto the earth's surface. Allocate active, dormant Andextinct volcanoes. The volcano is made up of four main parts : magma chamber, vent, cone and crater. There are about 600 volcanoes all over the world. Most of them are found along plate boundaries, where red-hot magma rises from the Earth's interior and erupts to the surface.
typical volcano is a hill with a pipe passing through its thickness, called the vent of a volcano with a magma chamber (magma accumulation area), from which the vent rises. In addition to the vent, small channels with magma, called mudflows and dikes, can also depart from the magma chamber. When high pressure is created in the magma chamber, a mixture of magma and hard stones - lava - rises up the vent and is thrown into the air. This phenomenon is called volcanic eruption . If the lava is very thick, it can solidify in the vent of the volcano, forming a plug. However, enormous pressure from below explodes the cork, spewing large blocks of rock called volcanic bombs high into the air. After each volcanic eruption, the lava solidifies into a hard crust. Volcanic hills with steep slopes are called conical, with gentle slopes - shield. Modern active volcanoes: Klyuchevskaya Sopka, Avachinskaya Sopka (Kamchatka, Russia), Isalko (El Salvador), MaunaLoa (Hawaii), etc.
Summary of the lesson "Relief and landforms." Next topic:
The relief is a set of irregularities of the earth's surface. Landforms are extremely diverse, thanks to them a special, unique appearance of the Earth is created. Landforms differ in different ways.
planetary forms landforms occupy vast expanses of the globe. They are based on different structures
earth's crust. These are, for example, continents, ocean beds and transitional zones from continents to beds, as well as mid-ocean ridges.
Megaforms reliefs are smaller, but not small. Examples are mountain belts, plains, ocean beds.
macroforms- these are ridges in the mountains, hills on the plains.
Mesoforms characterized by smaller sizes. These include ravines, beams, hills, etc.
Microforms relief is, for example, sinkholes, near-channel shafts.
Nanoforms - these are very small forms, such as bumps, ripples on dunes.
Large landforms were formed as a result of the influence of the internal forces of the Earth, and smaller ones - under the influence of external processes, such as the work of surface waters, weathering.
The main landforms are mountains and plains. Mountains occupy approximately 40% of the land, and plains - 60%.
Mountains- These are vast, highly elevated above the ocean level and highly dissected areas of the earth's surface. In the mountains, it is customary to single out individual mountain ranges, valleys, and basins; each ridge has a ridge, peaks, saddles. Exist different approaches to the classification of mountains.
- 1. The height of the mountains. Low mountains - up to 1000 m, medium-altitude - from 1000 to 3000 m, high - more than 3000 m.
- 2. According to the time of formation, mountains of pre-Riphean, Baikal, Caledonian, Hercynian, Mesozoic and Alpine (Cenozoic) folding are distinguished.
- 3. By origin, volcanic and tectonic mountains are distinguished. Among the mountains of tectonic origin, mountains are distinguished by structure: folded, blocky, folded-blocky. In the process of relief formation, horsts, grabens, and faults are formed.
Highlands - a mountainous country consisting of mountain ranges and relatively flat areas of the earth's surface located high above the ocean level.
Plateau - relatively flat, but folded into folds of rock layers, areas that arose on the site of the destroyed mountains.
Plains - vast areas of the earth's surface with small elevation fluctuations. Plains are distinguished by height above the level of the World Ocean: low - up to 200 m, highlands - 200-500 m, high - from 500 m and above.
By origin, the plains differ in the same way as the mountains - tectonic and volcanic. On land, tectonic plains are common, which were formed as a result of slow tectonic uplifts or subsidence. Volcanic plains are composed of basaltic lava, ash and tuff. They predominate at the bottom of the oceans, but are also found on land.
Depending on the origin and internal structure, several more types of plains are distinguished (accumulative, stratal, socle, denudation, plateaus, plateaus).
Accumulative plains were formed as a result of subsidence of the earth's crust or due to sediments of rivers (for example, the Indo-Gangetic lowland).
Reservoir plains located on the plates of young and ancient platforms (East European). As a rule, they are composed of pre-Neogene sedimentary rocks.
Basement plains formed on the shields of ancient platforms. They are composed of solid igneous rocks (plains of the Canadian, Baltic Shield).
Denudation plains - these are leveled sections of folded structures (Kazakh upland).
At the site of the outpouring of lava are formed trap plains.
Plateau- smooth wavy or slightly dissected, elevated and ledge-limited areas of the earth's surface, which are characterized by a horizontal or monoclinal occurrence of layers of dense sedimentary rocks.
Plateau - a highly elevated area of folded structures, which was leveled as a result of denudation (Vitimskoye area)
The morphology of the plains (appearance) is different. Plains are flat, inclined, concave, convex, wavy.
When characterizing the relief of the earth's surface, one should not forget that there are also relief forms invisible to the human eye. They are hidden by the waters of the World Ocean: underwater plains, volcanic ridges, etc.
Human activity has created man-made landforms (anthropogenic): quarries, waste heaps and ir.
