Negative landforms
positive forms relief
The history of the formation of the relief of the region.
Modern relief is the result of the development of the ancient Russian platform throughout long period. In its formation, 3 periods are distinguished:
1. Pre-glacial (long) - is the result of tectonic movements.
2. Glacial - accumulation of deposits of melted glacial waters.
3. Postglacial - as a result of the destroyed and accumulative activity of surface waters.
The plain appearance of the Russian platform and, together with it, the territory of the region acquired 500 million years ago as a result of the denudation (destruction) of the ancient mountains of Karelid.
AT further destruction occurs under the influence of tectonic movements. By the beginning of the definition on the territory of the region. a highly dissected relief was formed.
Large landforms were formed mainly before the glaciers in the Mesozoic and Cenozoic.
As a result of erosion-accumulative activity, the appearance of the region. changes radically.
Territory was covered with a thick layer of new rocks. The terrain was leveled. Many pre-glacial plains were not only buried, but accumulative ridges formed on them. The accumulation caused a significant restructuring of the river network. Large hollows formed after the melting of ice, flowing lakes formed.
Geologists found that the territory of the region. in the Quaternary period it was subjected to glaciations at least 3 times.
1. The most ancient Dnieper glacier, completely covered the territory of the region.
2. The Moscow glacier has spread over almost the entire territory of the region, except for the southern regions.
3. The Valdai glacier captured only the northwestern region.
The main stratum of the Quaternary deposits belongs to the Dnieper glaciation. Widespread in the region. landforms associated with the activity of melted glacial waters. Water flows created hollows, outwash plains, etc.
In the last period, there is a tendency for a general rise in the territory of the region. Top speed uplift is typical for the Smolensk and Vyazemskaya Uplands up to 3 mm per year. This is due to the activity of glaciers and melted glacial waters.
Hillocks and manes have a relative height of 1 to 10 m
The hills have a relative height of 10 to 100 m
The ridges are comparable in relative height with the hills. In contrast, they have an elongated shape.
There are closed, open on one side (semi-closed) and open on both sides (unclosed) negative landforms.
closed:
- saucers shallow, poorly expressed closed depressions in the relief various shapes depth no more 1 m.
- depressions They are depressions of various forms, with a depth of 1 to 10 m, gentle slopes, a well-defined lowest mark, or usually a small area of a flat bottom.
- hollows comparable in depth to depressions, but unlike them, they have steep or relatively steep slopes and a flat bottom.
- lowlands have varied, sometimes complex configuration, gentle slopes, uneven bottom. They occupy relatively large areas. Their depth varies from 10 to 100 m.
- hollows are characterized by the same depth as the lowlands, but have steep or relatively steep slopes similar to the depressions and a bottom that is flat or with separate irregularities.
Semi-closed:
- hollow
- dell
- beam. Related to human activities: ravines, gullies, gaps.
Open:
- Valley It is a linearly elongated relief depression with a uniform general bottom slope and clearly visible slopes. Valleys vary in size, depth, complexity of structure. The features of the device and the size of the valleys depend mainly on the genesis and time of their formation, the power of the watercourse, and the nature of the constituent rocks.
Big influence anthropogenic factors (deforestation, etc.) have an impact on the relief.
Negative landforms - concept and types. Classification and features of the category "Negative landforms" 2017, 2018.
RELIEF FORMS AND THEIR CLASSIFICATION
Under relief , as an object of study of geomorphology, is understood as the totality of all forms of the surface of the lithosphere (bulges, concavities and plains) of various geological structure and origin, located on different stages development, in complex combinations with each other and in complex interactions with the environment.
Now it is necessary to establish what are called its forms and elements, how forms can be classified and how they are formed.
DIFFERENT PRINCIPLES OF CLASSIFICATION OF RELIEF
Landforms can subsectionandbe:
1) by external signs;
2) by complexity;
3) by size;
4) by origin (genesis).
The first three are of auxiliary importance, the latter is the main one used in the course of geomorphological studies.
1. Classification of landforms according to outward signs
positive
negative
transitional, for example flat (horizontal).
In each group, there are closed and open forms
the positive form is a bulge; the negative form is concavity.
Closed landforms consider those that are limited on all sides by slopes or lines (plantar, brow, watershed).
Examples. A mountain that has slopes limiting it and a distinct plantar pine.
A karst funnel, often distinctly bounded by a closed edge line.
Unclosed landforms usually devoid of slopes on one or even two sides.
Example. A ravine bounded on three sides by slopes with distinct ridge lines.
Lines bounding landforms , are not always clearly identified on the ground.
Example. River valleys with gentle slopes of the primary banks, gradually turning into interfluve spaces.
The slopes themselves are in this case elements of the river valley. Lacking distinct ridges, they can be separated from watershed spaces by careful geomorphological studies.
2. Classification of landforms by complexity
simple shapes are small in size, do not include other shapes. Examples: mounds, gullies, etc.
Complex landforms can be of various sizes and consist of various combinations of simple shapes, often of different origins.
Example. Valleys of large rivers. Negative, open, complex relief form. Includes a variety of simple forms and their complexes. Such forms are river banks, river terraces (primary and alluvial), gullies and ravines on slopes, etc.
It is important to establish common concepts and terminology necessary for the study and description of relief.
Below is a brief description of some of the positive and negative landforms most commonly found in nature*.
positive landforms
Mound - an isolated hill with a pronounced sole line and a relative height of up to 50 m. Mounds are closed landforms, poured by man.
Hill - an isolated dome-shaped, less often conical hill with gentle slopes and a weakly expressed plantar line. The tops of the hills are sharp, rounded and flat. The relative height of the hills is up to 200 m.
hillock - an isolated dome-shaped hill with a pronounced sole line and a relative height of up to 100 m. In some cases, the shape of the hillocks can be conical. The slopes of the mounds are up to 25° steep; the tops are usually flat or slightly convex.
bumps - small positive landforms similar to hillocks, but having a height of no more than 1.0-1.5 m.
Uval - an elongated hill of considerable length (up to 10-15 km) with gentle slopes, even or convex, and with a weakly expressed plantar line. The top surfaces of the ridges are flat or slightly convex. Ridges are closed landforms, simple or complex, and have a relative height of up to 200 m.
Ridge - often a narrow, elongated hill with a slope of 20 ° or more. The ridges have flat or rounded apical surfaces and pronounced plantar lines. The relative height of the ridges is not more than 200 m. The ridges are closed landforms, simple and complex.
Plateau - an elevated plain, bounded by well-defined slopes, often steep or complex in shape; it represents a complex, closed form of relief. Usually the plateau is composed of horizontal layers. The surface of the plateau is flat, undulating, hilly, and often heavily dissected by negative landforms.
Mountain - an isolated positive landform with a relative height of more than 200 m, for the most part with steep slopes of various shapes and a pronounced plantar line.
The summit surfaces of mountains can be
domed,
pyramidal,
conical, etc.
A mountain that is a closed landform can be
simple and
more often complex.
Mountains should be distinguished from "tops" and "peaks", which are the most elevated points in mountain ranges and highlands.
mountain range - an elongated hill of considerable length, with a relative height of more than 200 m and steep slopes. A pronounced vertex (surface) is called a ridge. Being a complex form of relief, the mountain range is often complicated by rocky outcrops on the ridge and slopes.
mountain range - a low mountain range with gentle slopes and a flat or slightly convex summit surface. Ridges often consist of several denuded ridges (Timan Ridge, Donetsk Ridge).
uplands - very complex shape relief, strongly elevated above sea level and adjacent spaces, includes complex systems of mountain ranges, peaks, and other forms of mountainous relief (Armenian, Philippine highlands).
Negative landforms
dell or runoff trough - an elongated depression with gentle, usually vegetated slopes on three sides, open towards the general slope of the terrain. The edges of the hollows are usually not clearly expressed. The hollow is a simple open form of relief and has a shallow depth (up to several meters) and an insignificant length (up to 200-500 m).
scour - an elongated depression, having a small depth (from 0.1 to 1-2 m) and a width (from 0.3 to 4-5 m) and open towards the general slope of the terrain. The length of the ravine is insignificant (from 2-4 to 10-20 m); at the upper end of the ravine closes. The slopes of the ravine are steep, bare, and have a pronounced crest. The gulley belongs to simple landforms.
Ravine - an elongated depression, open, gradually expanding and sloping towards the general slope of the terrain. The slopes of the ravines are steep, in some places sheer, devoid of vegetation and have a distinct edge. The depth of the ravines is up to 50 m, the length can reach several kilometers.
Beam - an elongated depression with gentle slopes covered with vegetation, open towards the general slope of the terrain. The bottom of the beam has a gentle slope, a gently concave transverse profile and is fixed by vegetation. The edge of the slopes is distinctly expressed. The length of the beams can reach several kilometers. Depth and width are different. Large beams are complex landforms.
Valley - elongated, open (except in some cases), with a slope in one direction - a complex form of relief. The slopes of the valleys have different steepness and are often complicated by terraces, ravines, landslides and gullies. The bottom of the valleys can have different widths and is often complicated by ramparts, ridges, etc. The length of the valleys can reach hundreds and thousands of kilometers. At the meeting, the valleys do not intersect, but merge into one common one. Valleys through which rivers flow are called river valleys, and those without rivers are called dry.
Basin or depression - depression, closed on all sides and having slopes of different steepness and shape. The shape and size of the basins can be different; positive and negative landforms are often formed on the bottom and slopes. Small basins with a slight depth, gentle slopes and a flat or very slightly concave bottom are called saucers, or depressions.
Depressions and hollows can reach huge sizes. Above, the term was repeatedly used - the depression of the Atlantic (or Pacific, Indian) ocean. In this case, the basin will represent a part of the basin, isolated by underwater uplifts or groups of islands (North Pacific Basin, Somali Basin).
gutters (deep-sea trenches) - narrow, strongly elongated in length and deep depressions of the bottom of the seas and oceans, which are usually places of the greatest depths (Marian, Philippine, Javanese and other trenches).
The above classification of landforms is called morphographic. It is based on the characteristics of the external features of landforms, which are studied and described as completely as possible. However, from the above description of a number of forms, it can be seen that often the same name is applied to forms of various sizes and origins. This is especially clearly seen in the example of basins and depressions, but can be extended to other forms (for example, valleys and ridges). Thus, a more distinct division of landforms by size is needed. The study of landforms in terms of their dimensions is called morphometry.
In the above morphographic classification, morphometric data are partially found (for individual landforms, their approximate sizes are indicated), but they are of a random nature and do not have a single system. Taking into account the necessity of morphometric classification, a division of landforms according to size is given as a possible option (with an attempt to link this division with relatively established terminology).
3. Classification of landforms by size
It is based on the morphometric principle.
P planetary landforms .
Horizontal dimensions are measured in millions of square kilometers.
Vertically, the average difference in marks between positive and negative landforms reaches 2500 - 6500 m, and the maximum is almost 20,000 m.
Positive landforms are the continents, negative ones are the depressions of the oceans.
It is advisable to single out transitional forms, which should include the continental shelf, shelf, and continental slope.
2. Mega landforms .
Horizontal dimensions are determined by tens and hundreds of thousands of square kilometers.
Vertically, the difference in elevation between positive and negative landforms reaches 500-4000 m, the maximum does not go beyond 11,000 m.
Positive landforms - highlands, mountainous countries, underwater "swells" (Mid-Atlantic fell, Hawaiian underwater ridge), vast uplands (Volga), etc.
Negative: landforms - vast depressions (Brazilian, Argentinean) and basins at the bottom of the oceans, the Caspian lowland, etc.
It is advisable to single out transitional forms - areas of the continental shelf (for example, off the northern coast of Asia and North America).
These landforms are clearly shown on small-scale maps.
3. m acroforms .
Horizontal dimensions are determined by tens, hundreds and thousands of square kilometers.
Vertically, the difference in elevation between positive and negative landforms can reach 200-2000 m.
Positive landforms - mountain ranges (Trialeti, Chatkal), mountain nodes, peaks, individual mountains, etc.
Negative - large valleys, depressions such as the depression of the lake. Baikal, some underwater trenches, etc.
4. m landforms .
Horizontal dimensions are determined by hundreds and thousands (rarely hundreds of thousands) of square meters.
The relative height difference is up to 200-300 m, but is usually measured in meters and tens of meters.
Positive landforms - hills, terraces in valleys major rivers and upland, etc.
Negative landforms - fields and large sinkholes, ravines, beams, basins of small lakes, etc.
These landforms are satisfactorily reproduced on maps at a scale of 1:50,000; details can only be conveyed on larger scale maps.
5. Microforms of relief .
The horizontal dimensions of these landforms are determined square meters and hundreds of square meters.
The relative height difference is measured in meters and less often in tens of meters.
Positive landforms - small hillocks, riverbanks, barrows, road embankments, alluvial fans, etc.
Negative forms - gullies, shallow ravines, sinkholes small sizes, road cuts, etc.
For accurate transmission on maps, a scale of 1:10,000 and even 1:5000 is required.
6. Nanoforms of relief .
Horizontal dimensions are determined by square decimeters and meters.
The relative height is determined in decimeters, but can reach 1-2 m.
On maps of large scales are transmitted conventional signs and only in special cases can be transferred (individual forms) by horizontals of an additional section (1-0.5-0.25 m).
These landforms include hummocks, bushy braids, ruts, small gullies, etc.
7. The smallest landforms (topographic roughness ) .
Horizontal dimensions are determined by square centimeters and decimeters, for highly elongated forms they can reach square meters.
Relative excess is measured in centimeters and sometimes decimeters.
They are not depicted on the maps, but are palpable during precise geodetic work. An example of such landforms is sand ripples, furrows in fields, etc.
If a further finer subdivision is necessary, the above classification of seven groups can be subdivided into more fractional parts (for example, average landforms of the first, second, third, etc. order).
The above classifications of landforms clearly show that morphography and morphometry cannot give a complete characterization of landforms, which is necessary for a geomorphologist.
Example. depressions that have identical elements(deep point and faces - concave in profile and plan) and dimensions, can represent both a karst funnel and the crater of a small volcano.
When characterizing depressions only in terms of shape, one and the same terminology can be applied, and when depicted on a map, the same image methods can be used.
It is absolutely clear that such an approach to the image of a karst funnel and a volcano crater is completely wrong, since it makes it possible to convey only the form, but does not reflect the origin, relationships with surrounding forms, the geological structure, the geological processes developing in the given territory, and the possible further development of the depicted forms. relief. If we compare geological structure sides and bottom of a karst funnel with the sides and bottom of the crater, we will find fundamental differences in them.
Karst funnel is formed in the thickness of soluble rocks limestone, gypsum, etc.).
In the structure of the crater, on the contrary, there are rocks of igneous origin ejected during a volcanic eruption.
The origin of sinkhole and volcanic crater is also quite different.
The karst funnel was formed as a result of the chemical action of water on soluble rocks,
And the volcanic crater - as a result of a violent manifestation of the internal energy of the globe - an explosion of vapors and gases that had high temperature and under enormous pressure, etc.
From point of view relationships with other forms there are also certain differences between the sinkhole and the crater.
Karst funnels are usually located in groups, together with other karst landforms (fields, ponors, caves, etc.),
And volcanic craters are found together with volcanic landforms (for example, lava flows) and various manifestations of the Earth's internal energy (hot springs, geysers, etc.).
Minerals :
Having met a karst funnel, one can make an assumption that rocks that can be used as building materials (gypsum, limestone) are developed in this area, but we do not receive indications of the possible presence of other minerals.
In the region of the volcano crater, one can count on finds of deposits of volcanic tuffs, stone materials suitable for road construction, and some relatively valuable materials (agate, sulfur, sulfur compounds of various metals, etc.).
Soils and vegetation developed on limestones and on volcanic rocks will also be different.
Thus, outwardly identical shapes relief, but having a different genesis will testify to the great differences in the natural situation in the surrounding area. Such comparisons can be made for many landforms similar in outline, but different in genesis and internal structure.
Two terraces in a valley, rivers may have very similar external outlines, but one of them may be structural and the other alluvial. The first, composed of bedrock developed in the area, can serve as a place for the extraction of stone building materials, and the second can have large stocks sands and pebbles.
The differences can be just as great between remnant and accumulative hills, etc.
These comparisons clearly show that the external form does not determine all the features of the relief.
When depicting a relief on a map and deciphering it on aerial photographs, it is important to clearly identify the shape so that it is possible to determine the genesis of the relief in order to establish its main features and practical use.
Thus, for a complete description of the relief and the correct depiction of its forms on the map, you need to know the processes of its formation and development well.
Therefore, in addition to the examples already given above of the classification of landforms according to external features (in shape and size), it is necessary to analyze classification of landforms by genesis (origin), which has the most important practical and scientific value.
4. Genetic classification of relief
The most common genetic classification is the division of forms earth's surface into three categories (I.P. Gerasimov).
In a more detailed study of the relief, the foreground is genetic classification, which is complemented morphographic features relief and the age of its forms. By origin, landforms are divided into two large groups:
1) due to the activity of internal (endogenous) forces;
2) due to the activity of external (exogenous) forces.
The former, in turn, can be subdivided into:
a) landforms due to movements earth's crust(mountain-forming, oscillatory);
b) landforms caused by magmatic (volcanic) processes.
The latter can be divided into landforms, due to:
a) weathering processes;
b) the activity of flowing waters;
c) the activity of groundwater;
d) activities of the sea;
e) activity of snow and ice;
f) wind activity;
g) development of permafrost;
h) activity of organisms;
i) human activity.
In the general scheme in this classification are distinguished:
In each of these groups, relief forms are distinguished, created by certain exogenous processes:
erosion,
glacial,
gravity,
alluvial,
proluvial.
Under the cumulative impact of a number of processes, among the denudation relief, there are complex denudation landforms.
In relief analysis, the division into groups of denudation and accumulative forms is of particular importance.
Denudation surfaces in the relief of the Earth, these are areas of predominance of demolition, denudation. Their dominance is typical for areas of uplift of the earth's crust.
BUT cumulative surfaces typical for areas of deflection or neutral.
Alignment surfaces are formed when cutting off hills by denudation and filling depressions with destruction products. Typical in areas of stable, in conditions of very weak slow uplifts .
Denudation-accumulative forms are formed during the secondary occurrence of denudation in areas of accumulative relief (for example, alluvial fans strongly dissected by erosion).
Most relief formation agents are characterized by destructive, transporting (carrying) and accumulative activities.
Hence, under the influence of the same geological agent, landforms may arise due to destruction and entrainment rocks, and landforms due to the accumulation of brought matter.
The destruction and transfer of the substance that makes up the surface of the lithosphere, carried out by the entire set of external geological agents, denote general term- denudation, and the landforms caused by this process are called denudation.
These landforms are further subdivided into forms due to destructive activity. water streams(rivers), and are called erosional.
forms due to the destructive activity of the sea, - abrasive etc.
Landforms resulting from the accumulation of matter are called accumulative and subdivided into glacial, eolian, etc.
Genetic, morphographic and morphometric classifications may be partly mutually related.
Relief Type Definition
Terrain type - certain combinations of relief forms, regularly repeating over vast expanses of the lithosphere surface and having a similar origin, geological structure and history of development.
In this definition of the type of relief, it becomes necessary combine types into larger units, For example into groups of relief types(type group mountainous terrain, flat relief). Such an association can be made according to various characteristics (for example, a group of types of glacial relief).
Groups of relief types can be combined into units of a larger order(the complex of the continental relief and the complex of the relief of the bottom of the oceans, etc.).
When identifying and studying large relief complexes, it should be taken into account that it will be necessary to operate with two unequal values. This is explained by the fact that the relief of the land has been studied incomparably better than the relief of the bottom of the World Ocean.
When selected in special complexes the relief of the continents and the relief of the bottom of the oceans should be distinguished and equivalent transitional relief complex, since the relief of the continents and the ocean floor is connected by a number of transitions, represented by the relief of coasts, islands, peninsulas, the bottom of the seas located on the continental shelf, the relief of the shelf, the continental slope, mediterranean seas etc.
The relief of the earth - it is a set of forms of the earth's surface. Each landform is a three-dimensional natural body that occupies a certain volume of the earth's crust. Therefore, just like the earth's crust as a whole, the landform is a natural unity geological structure, lithological composition of rocks and surface shape.
Exogenous landformsformed as a result of a certain denudation or accumulative natural process. This process is controlled and directed by tectonic movements. Therefore, within tectonic structures and blocks of the earth's crust, a certain combination of repeating landforms is formed that determines the structure natural landscape. Landforms and their elements are the lithogenic basis of PTC of various ranks.
The relief of the Earth creates the interaction of oppositely directed endogenous and exogenous forces and processes.
endogenous forces,coming from the bowels of the Earth, set in motion large blocks and structures of the earth bark, form mountains and valleys. Endogenous processes develop independently and control exogenous processes.
Exogenous processes– external geological processes occurring on the surface of the Earth. They develop under the influence solar radiation, gravity, moving atmosphere, water, ice. Exogenous processes destroy mountains, fill depressions with precipitation, level the surface of the Earth. Vegetation, animals and humans are involved in exogenous processes. The leading role in the formation of relief is played by endogenous forces that determine the tectonic regime of the earth's crust. They determine and control exogenous processes, ecological regimes and life on Earth in general.
Landforms are limited to horizontal or slanted faces. They are called genetically homogeneous surfaces or elements of landforms (surfaces of a plateau, plain, slope). When crossing the faces of the relief, fractures or edges are formed that separate one face or shape from another. Relief edges are usually natural boundaries of the NTC.
Each facet of the relief is entirely and completely created by any one or combination of relief formation processes (weathering, abrasion, erosion, deflation, nivation, various accumulation, etc.). For example, the surface of a floodplain or floodplain terrace, a deluvial or scree slope of a lacustrine-glacial plain, a trap plateau.
Landforms are positive and negative regardless of the absolute height.
positive forms– these are protrusions, bulges in relation to the surrounding lower surfaces: protrusions of the continents in relation to oceanic depressions, mountains and hills among the plains, floodplain crests, coastal ridges, dunes, terminal moraine ridges, dunes, hillocks, bumps, ridges in swamps in relation to hollows .
Negative forms– concave, lowered landforms in relation to the surrounding raised surfaces: ocean trenches, lake baths, lowlands and lowlands among the plains, concave swamp depressions, intermountain depressions, river valleys, drainage funnels in the mountains and on the slopes, small depressions of karst or thermokarst origin, runoff hollows, saucers in the steppe, ravines, beams, hollows, logs and etc.
If the positive forms of relief are characterized by denudation, destruction and removal of material and water, drying, then the negative forms are characterized by the accumulation of materials removed from the positive forms, and watering.
The disadvantage of dividing the relief forms into negative and positive ones is its relativity, which depends on the choice of the surface or the height level of the surface, in relation to which the counting is carried out.
So, for example, the West Siberian Plain is a negative form in relation to Ural mountains and the Central Siberian Plateau. At the same time, the Surgut lowland is a negative form in relation to the surrounding higher areas. West Siberian Plain. It is characterized by almost continuous swampiness and lakes. And on the same West Siberian in general flat plain elevated plains protrude, which are called continents and ridges: Belogorsky mainland, Agansky ridge, Verkhnetazovsky upland. These elevated plains are dissected, drained, devoid of swamps and lakes.
Landforms vary in size and form a series of forms of various orders from the largest to the smallest: megaforms 1st order macroforms 2nd order, mesoforms of the 3rd order, microforms 4th order and nanoforms 5th order.
Megaforms– the most large forms relief of the earth's surface: continental ledges, depressions of the oceans, mountain belts; due to forces of a planetary nature. Continents (continents) are the largest positive landforms (geotectures) that protrude above the level of the World Ocean in the form of land. The continents were formed on the largest tectonic structures of the Earth with a thick (35-45 km) earth's crust, which differs from the oceanic one in the development of a granite layer. peripheral parts, the margins of the continents, having a continental structure, flooded in the Neogene– Quaternary time are continental shelves-shelves.
macroforms– the largest forms of the Earth with height fluctuations of up to several hundred meters or more, with a length measured in thousands of kilometers. Macroforms are vast plains, plateaus, mountain ranges. Macroforms were formed on the largest geoblocks: shields, platforms, slabs, geosynclicals.
Mesoformsarise under the influence of exogenous forces and processes. They are moraine hills, mud hills, ravines, dunes, basins, valleys and river terraces, with a height amplitude of up to tens of meters. Mesoforms develop within the macroform and are therefore also controlled by tectonics.
Microforms– small landforms, which are details and structural elements of mesoforms: mounds and ruts of various genesis, various parts of slopes, near-channel ramparts of floodplains, oxbow lakes and old rivers, alluvial channel formations of rivers - spits, middle rivers, islands, karst funnels and alluvial cones of watercourses, steppe saucers, subsidence depressions, etc.
Nanoforms– small forms associated with the influence and development of vegetation, the activities of animals and humans: mounds of earth-moving animals, pits and digs of animals, goat trails on slopes, permafrost mounds, ridges and hummocks in swamps and tundra, polygonal permafrost and post-permafrost hilly-depression forms and etc.
Distinguish phytogenic forms:phytogenic tuberosity in areas subject to deflation, tussocks of grasses, sedges, shrubs, root eclipses - sparks associated with phytogenic tuberosity in wet and damp forest types;zoogenic forms– ground squirrels, molehills, digging wild boars, mounds of ant colonies, etc.
Landforms of various orders are the lithogenic basis of the NTC of various taxonomic ranks.
More principled and logical genetic classification relief forms belongs to Yu.A. Meshcheryakov and I.P. Gerasimov, who distinguish between morphostructures and morphosculptures of relief (1967).
Under morphostructures they offer understand the large forms of the earth's surface, in the formation of which the main role belongs to endogenous processes and in the morphology of which geological structures are clearly reflected. Morphostructures differ in orders of magnitude and depend on the order of the tectonic structures that are their foundation. The largest morphostructures correspond to the largest elements of the earth's crust: protrusions of the continents, depressions of the oceans, mid-ocean ridges, etc. Morphostructures of a smaller order - platform plains, mountainous countries of folded areas. Space images reveal a whole subordinate system of morphostructures associated with the block differentiation of the earth's crust, which becomes noticeable on small-scale remote data due to differences in the structure of the PTC, the visibility of boundaries, which are often faults in the earth's crust.
Under morphosculptures understood small landforms, in the formation of which leading role exogenous processes play: river valleys, glacial hills, swamp systems, dunes and dunes, takyrs and sors, etc. Morphosculptures are controlled by the morphostructures that contain them.
Landforms have different age- the time elapsed since their formation. The age of the morphosculpture usually does not go beyond the anthropogenic period; morphostructures are older (Neogene, Paleogene, Mesozoic).
Morphostructures of various orders are characterized by a combination of regularly repeating interrelated landforms of the same age, genesis, appearance, which arose under conditions of a certain direction of the latest tectonic movements and exogenous processes.(for example: hilly-moraine, valley-beam, swamp-outland, etc.). Such combinations are called morphogenetic type of relief or simply relief type. Relief types determine the morphological structure of the natural landscape.
Terrain types depend on absolute heights, that is, heights above sea level. Absolute heights are associated with: the genesis of landforms, their age, history of development (and in connection with this - the lithological composition of rocks and sediments), dissection, permafrost, a set of meso- and macroforms, water balance, swampiness and lakes and other parameters, in general, the structure of the NTC and the ecological regime of lands.
The morphology of the PTC depends on the height above sea level. Erosion intensifies on the elevated plains, a ravine-gully network is formed, deep straightened and narrow valleys of watercourses, swampiness and lakes decrease, landscapes of the type opium, overfill(see p. 165). The low-lying plains are poorly dissected, they are characterized by strongly meandering rivers with wide flat valleys, severe swampiness and lakes. Woodland type landscapes are formed on them.
To estimate the absolute heights of the surfaces of landforms, it is best to use general geographical maps. Usually they have a scale of high-rise steps. For example, in landscape mapping Krasnoyarsk Territory and the basin of Lake Baikal, altitudinal relief steps were identified that determine qualitative changes in the structure and ecology of the NTC: low NTC (0-50 m above sea level), low (51-100 m), slightly elevated (101-200 m), elevated ( 201-500 m), low-mountain (501-1200 m), mid-mountain (1201-3000 m), high-mountain (3001-5000 m) (Kireev, 1996).
There are positive (rising above the surface) and negative (deepering from the surface) landforms.
Irregularities in the surface of the earth's crust can be of a different order.
The Greatest (planetary) forms relief - these are oceanic depressions (negative form) and continents (positive form)
The area of the earth's surface is 510 million sq. km. of which 361 mln. km (71%) occupies and only 149 million square meters. km (29%) - land
Land is unevenly distributed among the oceans. In the Northern Hemisphere, it occupies 39% of the area, and in the Southern - only 19%.
The mainland or part of the mainland with nearby islands is called part of the world.
Parts of the world: Europe, Asia, America, . As a special part of the world, Oceania is distinguished - a collection of islands in the central and southwestern parts.
Continents and islands divide the single World Ocean into parts - oceans. The boundaries of the oceans coincide with the shores of the continents and islands.
Oceans protrude into the land by seas and bays.
Sea - a part of the ocean, more or less isolated from it by land or elevations of underwater relief. There are marginal, inland, inter-island seas.
gulf - part of the ocean, sea, lake, deeply protruding into the land.
strait - relatively narrow body of water bounded on both sides by land. The most famous straits are: Bering, Magellan, Gibraltar. The Drake Passage is the widest, 1000 km, and the deepest, 5248 m; the longest is the Mozambique Channel, 1760 km.
Planetary relief elements are divided into second-order relief forms - megaforms (mountain structures and large plains). Within megaforms allocate macroforms (mountain ranges, mountain valleys, depressions of large lakes). On the surface of macroforms, there are mesoforms (forms medium size- hills, ravines, beams) and microforms (small forms with height fluctuations of several meters - dunes, gullies).
Mountains and plains
- vast areas of land or the ocean floor, significantly elevated and strongly dissected. The mountain is a single uplift with a peak, having a relative height of more than 200 m. Most of these mountains are of volcanic origin. Unlike a mountain, a hill has a lower relative height and gentler slopes, gradually turning into a plain.
Mountain ranges are linearly elongated uplifts with clearly defined slopes and ridges. The ridge part of the ridge is usually very uneven, with peaks and passes. The ridges connect and intersect, forming mountain ranges and mountain nodes - the highest and difficult sections mountains Combinations of mountain ranges, often heavily destroyed, intermountain basins and leveled elevated areas form highlands. According to the absolute height, mountains are distinguished high (above 2000 m), medium high (800 - 2000 m) and low (not higher than 800 m).
The general pattern of relief changes with height is its. The higher, the more intense the weathering in the mountains. The tops of the mountains, rising above the snow line, bear on themselves. Below, glacial tongues descend, feeding turbulent mountain streams, streams dissect the slopes with deep valleys, and move pumps down. At the foot, the pumps and the material crumbling from the slopes stick together, smoothing out the bends of the slopes, creating foothill plains.
– surface areas with small height differences. Plains with absolute altitude no more than 200 m, are called lowlands; no more than 500 m - elevated; above 500 m - upland or plateaus. On the continents, most of the plains were formed on platforms and folded layers of the sedimentary cover (stratified plains). Plains that have arisen as a result of the demolition of destruction products from the remaining base of the mountains (basement) are called basement. Where material accumulates, leveling the surface, accumulative plains form. Depending on the origin, the plains are sea, lake, river, glacial, volcanic.
Deep-water plains are hilly, undulating, less often flat. Significant thicknesses of sediments accumulate at the foot of the continental slope, forming sloping plains. The shelf also has a flat relief. Usually it represents the outskirts of the platform, which turned out to be under sea level. On the shelf, there are landforms that have arisen on land, riverbeds, and forms of glacial relief.
Formation of the Earth's relief
Features of the Earth's relief
Negative landforms are relatively low areas of the land surface or the bottom of water bodies: valleys, depressions, ravines, construction pits, etc.
Source: Dictionary of architectural and construction terms
- - coastal relief forms are abrasion and accumulative. Abrasive forms: a steep, often sheer coastal ledge or cliff, a wave-cutting niche and a coastal or abrasion platform...
Geographic Encyclopedia
- - convex landforms; relatively elevated areas of the earth's surface, rising above the average level of a given area of \u200b\u200bland ...
- - landforms created by the activity of water flows, both permanent and temporary ...
Natural science. encyclopedic Dictionary
- - the shape of the earth's surface; separate three-dimensional geol. bodies occupying certain volumes of the earth's crust. Restricted to 2D features, or terrain faces. Forms m. convex, or put ...
Natural science. encyclopedic Dictionary
- - relatively low areas of the land surface or the bottom of water bodies: valleys, depressions, ravines, construction pits, etc. Source: Dictionary of architectural and construction ...
Construction dictionary
- - elements of relief, characterized by the integrity of the structure. They can be simple or elementary or complex...
Geological Encyclopedia
- - formed as a result of the accumulation of urban settlements brought by water, wind, ice, etc. They are usually correlated with denudation forms, due to the destruction of which arose ...
Geological Encyclopedia
- - resulting from denudation ...
Geological Encyclopedia
- - similar but appearance forms that arose in different ways and in decomp. conditions...
Geological Encyclopedia
- - formed as a result of accumulation of sediments by means of any exogenous agent of morphogenesis or products of volcanoes. activities on the surface of both low-lying and elevated and often dissected land ....
Geological Encyclopedia
- - arising from landslides: landslide cirques, landslide terraces inclined to the side, opposite movement landslides, mounds, ridges, small ledges on the surface of a slumped massif and ...
Geological Encyclopedia
- - arising on the earth's surface as a result of the activities of animals and plants - coral islands and reefs, peat bogs, especially upland, peat mounds, swamp hummocks, termite mounds, anthills, mole and ground squirrel ...
Geological Encyclopedia
- - low areas of the earth's surface, regardless of abs. or relative height surrounded by an elevated surface, or positive landforms...
Geological Encyclopedia
- - the main ones: 1. Baric lows, or simply lows, or cyclones. 2. Baric highs, or anticyclones...
- - relatively low forms of the earth's surface, lying below the average hypsometric level of a certain area of \u200b\u200bthe land or seabed. Contours O. f. R. depend on the choice of this average...
- - relatively increased irregularities of the earth's surface, lying above the average hypsometric level of the adjacent area of \u200b\u200bthe land or seabed ....
Great Soviet Encyclopedia
"Negative landforms" in books
Landforms
From the book Lessons of a skilled carver. We cut out figures of people and animals, dishes, figurines from wood author Ilyaev Mikhail DavydovichTypes of relief A significant place in the work on wood is occupied by various reliefs. Doing them requires some skill. The more difficult the terrain, the more skill is needed. A relief is a semi-volumetric image placed on a plane and protruding to varying degrees.
Alpine type of relief
From the book Big Soviet Encyclopedia(YOU) the author TSBAlpine landform
From the book Great Soviet Encyclopedia (AL) of the author TSBrelief section
From the book Great Soviet Encyclopedia (CE) of the author TSBbump maps
From the book Great Soviet Encyclopedia (KA) of the author TSBRelief faces
From the book Great Soviet Encyclopedia (GR) of the author TSBpositive landforms
From the book Great Soviet Encyclopedia (PO) of the author TSBRelief inversion
From the book Great Soviet Encyclopedia (IN) of the author TSB From the book Keys to Success author McCallum JohnChapter 35 for relief About forty years ago in a small town on west coast there was a large, shapeless building surrounded by a high wooden fence. It looked like a concentration camp, but in fact it was a factory and a warehouse where
Relief study
From the book to you, tourists! authorRelief study One of the most important objects observation is a relief, i.e. a set of irregularities of the earth's surface - lowlands, plateaus, mountain ranges, river valleys, ravines, beams, etc. Having studied the terrain, you can get an idea of \u200b\u200bits
