View of the landform by absolute height. Landforms
Terrain - any section of the earth's surface with all its irregularities and objects (objects) located on it.
From this definition it follows that the terrain consists of two elements: the earth’s surface itself with all its irregularities - this is what topographers call relief, and everything that is on it is called local objects.
The main element of the terrain is the terrain. It has the greatest impact on water reserves, the characteristics of soil and vegetation cover, roads, the location and layout of settlements, and even the climate.
The relief, depending on the natural conditions of the area, can be of the most varied shapes. But if you look closely at all the unevenness of the earth's surface, you can still notice the so-called main (typical) relief forms: mountain, ridge, basin, hollow and saddle (Fig. 1). They are found both in pure form and in combination with each other and, in turn, have their own varieties.
A hollow is a depression that slopes down in one direction. The line running along the bottom of the hollow is, as it were, a bed for water drainage; therefore, it is called a spillway line or simply a spillway.
A saddle is a place between two adjacent hills (Fig. 1), which is also a connection of two valleys diverging in opposite directions.
The basin is a closed depression. Depending on its size, it is sometimes called a depression, and sometimes a pit.
The second important element of the area is local objects.
So, depending on their external form and purpose, they are divided into the following groups:
Populated areas (cities, towns and country-type settlements, villages, villages, individual courtyards);
Industrial, agricultural and cultural buildings (factories, factories, power plants, mines, elevators, Palaces of Culture, cinemas, etc.);
Road network (railroads, highways, highways, dirt and country roads, field and forest roads, trails);
Soil and vegetation cover (forests, shrubs, gardens, meadows, arable lands, vegetable gardens, swamps, sands, etc.);
Hydrography (rivers, lakes, canals and various structures attached to them: dams, ports, piers, ferries, etc.);
Power and communication lines (radio stations, postal, telegraph stations, communication lines, etc.).
According to topographers, there are two types of terrain: open or closed.
The open area is a plain with a small number of groves, bushes, and rare settlements. It allows you to view at least 75% of its entire area from the heights available on it.
A closed area is characterized by a large number of local objects and a pronounced relief. It is usually covered with forests, bushes, gardens
From the point of view of the terrain's passability, that is, the presence of obstacles on it: rivers, lakes, swamps, ditches, gullies, ravines, structures, etc., it is divided into rough and uncrossed.
Rough terrain is one in which more than 20% of the area is occupied by obstacles. It includes all mountainous and highland regions, regions of Right Bank Ukraine with a large number of ravines, many regions of the Karelian Autonomous Soviet Socialist Republic with numerous lakes (Fig. 6), regions of the Estonian SSR and the Kaliningrad region with a predominance of hills.
Areas of terrain whose surface within the horizon visibility range (up to 4-5 km) is flat or slightly hilly, with very gentle slopes (up to 2-3°) and slight fluctuations in height (20-30 m) are classified as flat terrain
Hilly terrain has a large number of hills, hollows, ravines, gullies, but the steepness of their slopes on average fluctuates around 5o, that is, it allows the movement of all types of equipment and vehicles along them. It can also be either open or closed, crossed or uncrossed.
Mountainous terrain is characterized by alternating mountain ranges over valleys, saddles and gorges. It is dominated by steep slopes, often turning into cliffs, and rocks. Depending on the height, mountains are divided into low (from 500 to 1000 m), medium-height (from 1000 to 2000 m) and high (more than 2000 m).
Planning structure of the city. Functional zoning of a settlement.
The architectural and artistic expressiveness of the city depends on:
· mutual arrangement of functional, territorial and construction zones;
· availability of parks, gardens, green spaces, water spaces;
· color scheme of buildings; presence of architectural monuments;
· expressive silhouette of the settlement, depending on the number of storeys of buildings;
· architectural expressiveness of entrances to the city;
· improvement of the production area; the presence of public centers and squares;
· placement of streets and roads;
· adjacent landscapes.
Various philosophical and religious concepts of the East - Feng Shui, Punk-Su, etc. (Japan, China) strictly regulate human actions. Not only the components of the surrounding space are subject to the regulation, but also the location of the settlement and its surrounding objects in the cardinal directions and in relation to each other. There should be a hill or mountain in the north of the settlement, a village at the foot, and a body of water on the south side. In their opinion, it is precisely this location of the settlement and its surrounding objects that has a beneficial effect on humans.
Town planning regulations determine the conditions, which must be ensured when planning a settlement:
· safe sanitary and hygienic environment;
· comfortable, if possible equal, social living conditions;
· convenient and quick cultural and social services for the population of all ages;
· convenient forms of communication between all residents.
Satisfaction of these conditions is achieved as a result of the correct location of the elements of the planning structure within the boundaries of the populated area. Planning structure call the division of a residential area into structural and planning units, independent in organization, but identical in functionality. Structural planning unit- this is a residential formation (part of the territory of a residential zone) in which the practical (utilitarian) needs of the population for the convenience of life, everyday life, cultural and public services and work are taken as a basis. The elements of the planning structure of a settlement are: streets, squares, neighborhoods, personal plots, residential and public buildings, industrial and outbuildings, green spaces and other amenities. The elements of the planning structure also include various engineering structures. The relative arrangement of the elements of the planning structure determines the cadastral value of land in settlements.
The planning structure reflects the unity and interconnectedness of various parts of the urban organism.
The predominance of one of the factors influencing the formation of the planning structure, or the total impact of several, determines type of city planning structure: compact, dissected, dispersed and linear.
Compact type characterized by the location of all functional zones of the city in a single perimeter. The main advantages are the compact form of the plan, good accessibility of the center, the least degree of disruption of the natural environment with a point concentration of settlement. The advantages of this type of planning structure can be fully realized only with limited settlement sizes.
Exploded type occurs when the city’s territory is crossed by rivers, ravines or a transit railway. When urban development is dissected or when the main industrial area is significantly removed from the residential zone, the leading compositional role in the spatial unification of separated parts and disconnected functional zones of the city can be played by extensive intercity recreational areas.
Dispersed type involves several urban planning formations connected by transport lines. The emergence of a dispersed type is determined by the nature of the city-forming group of enterprises in a given city (for example, mining industry) or natural and climatic conditions.
Linear structure received cities located on shaded areas of the coastal strip of seas and large rivers, mountain valleys, etc. The advantages of linear structures - saving time on movement and the proximity of development to the natural environment - continue with the growth of linear urban developments.
With any planning structure of a city, the expressiveness of its appearance is determined by the nature of the unification of its individual parts by a system of transport highways, which can be radial, radial-ring, fan (beam), rectangular, free and combined, in which any of them can be combined.
Types of city planning systems
a) radial-ring, b) fan-shaped (radial), c) rectangular, d) free.
The lands of settlements, taking into account their functional use, are divided into residential, industrial and recreational zones.
The living area is intended for placement of housing stock, public buildings and structures, research institutes and their complexes, as well as individual municipal and industrial facilities that do not require the construction of sanitary protection zones, intercity communication routes, streets, squares, parks, gardens, boulevards and other public places use.
The production area is intended for placement of production enterprises and related facilities, complexes of scientific institutions with their pilot production facilities, municipal and warehouse facilities, external transport structures, non-urban and suburban transport routes.
Recreational area includes urban forests, forest parks, forest protection zones, reservoirs, agricultural lands and other lands, which, together with parks, gardens, squares and boulevards located in residential areas, form a system of open spaces.
Within the specified zones, territories for various purposes are allocated: residential buildings, public centers, industrial, scientific and scientific-production, municipal and warehouse, external transport, mass recreation, resorts (in cities and towns with medicinal resources), protected landscapes.
On the territory of small and medium-sized rural settlements, as a rule, residential and industrial zones are distinguished. In the territory of large and large rural settlements, it is necessary to identify all functional zones.
In historical cities, zones (districts) of historical buildings should be distinguished.
Subject to compliance with sanitary, hygienic and other requirements for the joint placement of objects of different functional purposes, the creation of multifunctional zones is allowed.
In areas exposed to hazardous and catastrophic natural phenomena (earthquakes, tsunamis, mudflows, floods, landslides and collapses), zoning of the territory of settlements should be provided taking into account reducing the degree of risk and ensuring the sustainability of functioning. Parks, gardens, outdoor sports fields and other elements free from development should be located in areas with the highest degree of risk.
In seismic areas, functional zoning of the territory should be provided on the basis of microzoning according to seismicity conditions. In this case, areas with less seismicity should be used for development.
In areas with complex engineering and geological conditions, development sites are used that require lower costs for engineering preparation, construction and operation of buildings and structures.
It is necessary to distinguish between functional and territorial zones. The composition of the lands of settlements may include land plots classified in accordance with urban planning regulations to the following territorial zones:
· social and business;
· production;
· engineering and transport infrastructures;
· recreational;
· agricultural use;
· special purpose;
· military facilities;
· other territorial zones.
The boundaries of territorial zones must meet the requirements that each land plot belongs to only one zone.
The rules of land use and development establish urban planning regulations for each territorial zone individually, taking into account the characteristics of its location and development, as well as the possibility of a territorial combination of various types of use of land plots (residential, public and business, industrial, recreational and other types of use of land plots).
For land plots located within the boundaries of one territorial zone, a unified urban planning regulation is established.
If the residential area of a settlement is built up with houses of different types, number of storeys and from different building materials, then it is advisable to carry out construction zoning of the residential area. The allocation of development areas with houses of different types, number of storeys and using different building materials from which they are built is called construction zoning. This zoning allows for better systematization of residential areas. In this case, the territory of the settlement will be used more efficiently, and the costs of landscaping and engineering will be more optimal. When placing residential buildings on the territory of a rural settlement, three main construction zones are distinguished: low and medium-rise multi-apartment (sectional) buildings; developments with blocked houses; development of private residential buildings. When locating a residential area in the suburbs, medium-sized and small cities, an additional multi-storey building zone is allocated.
The task of construction zoning consists of establishing boundaries between construction zones. This is done in two ways. The first is that the border is set along the territory of the block, the second is that the border coincides with the axis of the street. The choice depends on the characteristics of the existing and planned development. With the first method When forming a zone boundary, both sides of the street are built with houses of the same types and number of storeys, achieving greater architectural expressiveness. At the same time, the costs of improvement and engineering equipment of the street are reduced, and opportunities are created for its better organization. With the second method placement of the zone boundary reduces the architectural expressiveness of the street.
In the case where sections of sectional development are adjacent to personal plots of individual and blocked development, they are separated by a strip of green space.
In rural areas, in order to effectively use engineering equipment and reduce the cost of improvement, it is recommended to place sectional apartment buildings in the central part of the village, near the public center, and sometimes include them in the composition of the public center. Individual houses are best located on the periphery of the residential area. Under appropriate conditions, mixed development can be envisaged in residential areas.
Compliance with construction zoning is not strictly mandatory. However, when compiling the cartographic part in tabular form (explication), it is necessary to provide a quantitative expression of the housing stock, buildings and the construction of the public and business zone by type of construction zoning.
FUNCTIONAL ZONES OF A SETTLEMENT. LOCATING A PRODUCTION ZONE IN THE CONSTRUCTION OF A SETTLEMENT. TECHNOPARKS. INTEGRATION ISOLATION AND DIFFERENTIATED APPROACH TO LOCATION OF INDUSTRIAL ENTERPRISES
8. 1Functional zones of a settlement.
8.2 Location of the production zone in the construction of a populated area. 8.3.technoparks.
8.4. Integration, isolation and differentiated approach to industrial placement. enterprises
8.1. functional zones of the settlement
The city has the following urban planning zones, different in their functions (Fig. 1).
Figure 1. Conceptual diagram of the relative location of the main functional areas of the city: 1 - residential area; 2 - industrial zone; 3 - warehouse area; 4 - external transport zone; 5 - green recreation area; 6 - sanitary protection zone; 7 - direction of river flow; 8 - direction of prevailing winds for the hottest quarter (month) of the year
Industrial zone includes industrial enterprises serving their cultural and everyday institutions, streets, squares, green spaces.
Residential zone- territory intended for housing. It can accommodate neighborhoods and residential areas, cultural and public service enterprises, individual harmless enterprises, streets, squares, landscaping facilities, warehouses, reserve areas, transport facilities.
Sanitary protection zone- green spaces with a width of 50 to 1000 m, protecting territories from the harmful influence of industry and transport.
Transport zone- devices for external transport (water, air, rail).
Warehouse area- territory of various types of warehouses.
The formation of functional zones and the placement of objects on them is regulated by MDS-30-1.99 and SNiP 2.07.01-89*.
The transport network of large cities is turning into a system of surface, elevated and underground highways intersecting at several levels. In world practice, there are already transport interchanges on five levels. With an increase in the number and variety of vehicles, the degree of complexity of the city's transport network increases and, thus, the system of connections between functional areas improves. The planning structure depends on the location of the city on the terrain. There are compact plan forms, dissected, dispersed with evenly distributed areas, dispersed with a predominant area and linear. The complexity of the planning structure of large cities also lies in the fact that a wide variety of industrial enterprises cannot be located on the territory of one industrial zone. This causes division of residential areas. New residential areas are emerging on the periphery of the city, and new recreation areas are being formed. New industrial zones lead to the emergence of sanitary protection territories. The growth of the city contributes to the development of external transport and the expansion of the transport zone.
Functional zoning The modern historical city is more multifaceted, especially in its central part, where a huge number of objects for various purposes are located in close proximity to each other.
Functional zoning for its intended purpose is reflected in the state urban planning cadastre of the city in accordance with SP-14-101-96 “Approximate regulations on the urban planning cadastre service of a constituent entity of the Russian Federation, city (district).” So, for example, for Moscow, the state urban planning cadastre service subdivides the city’s territory in the following order:
functional zones for specialized purposes - administrative and business, teaching and educational, cultural and educational, trade and household, medical and health, sports and recreational, educational, individual residential development, multi-apartment residential development, municipal and warehouse, industrial, special, housing -municipal, natural-recreational, environmental protection;
mixed-use functional zones - public, residential industrial, natural, public-residential, public-industrial, industrial-residential, public-industrial-residential, natural-public, natural-residential, natural-industrial, natural-public-residential, natural-social-industrial, natural-industrial-residential.
Infrastructure areas are divided into streets and roads; territories of external transport; water surfaces.
Urban planning zoning is also carried out using the following lines of urban planning regulation:
red lines of the road network;
residential building lines;
blue lines - boundaries of river water areas;
railroad right-of-way boundaries;
boundaries of technical zones of the designed metro lines;
boundaries of technical (security) zones of engineering structures and communications;
boundaries of territories of historical and cultural monuments;
boundaries of protective zones of historical and cultural monuments;
boundaries of historical and cultural protected areas;
boundaries of zones regulating the development of historical and cultural monuments;
boundaries of protected landscape zones;
boundaries of specially protected natural areas;
boundaries of protective zones of specially protected protected areas;
the boundaries of the territories of the natural complex of Moscow that are not particularly protected;
boundaries of green areas not included in the natural complex of Moscow;
boundaries of water protection zones;
boundaries of coastal zones;
boundaries of sanitary protection of drinking water supply sources - boundaries of the 1st sanitary protection zone, boundaries of the 2nd sanitary protection zone, boundaries of the rigid zone of the 2nd sanitary protection zone;
boundaries of sanitary protection zones.
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Lesson questions:
1. Types and forms of terrain. The essence of depicting relief on maps using contour lines. Types of contours. Depiction of typical relief forms by horizontal lines.
1.1 Types and forms of terrain.
In military affairs terrain understand the area of the earth's surface on which combat operations are to be conducted. Irregularities in the earth's surface are called terrain, and all objects located on it created by nature or human labor (rivers, settlements, roads, etc.) - local items.
Relief and local objects are the main topographical elements of the terrain, influencing the organization and conduct of combat, the use of military equipment in combat, conditions of observation, firing, orientation, camouflage and maneuverability, i.e., determining its tactical properties.
A topographic map is an accurate representation of all the most tactically important elements of the terrain, plotted in a mutually precise location relative to each other. It makes it possible to explore any territory in a relatively short time. A preliminary study of the terrain and decision-making for a unit (unit, formation) to carry out a particular combat mission is usually carried out on a map, and then clarified on the ground.
The terrain, influencing combat operations, in one case can contribute to the success of troops, and in another have a negative impact. Combat practice convincingly shows that the same terrain can give greater advantages to those who study it better and use it more skillfully.
According to the nature of the relief, the area is divided into flat, hilly and mountainous.
Flat terrain characterized by small (up to 25 m) relative elevations and relatively low (up to 2°) slope slopes. Absolute heights are usually small (up to 300 m) (Fig. 1).
The tactical properties of flat terrain depend mainly on the soil and vegetation cover and the degree of ruggedness. Its clayey, loamy, sandy loam, and peat soils allow the unimpeded movement of military equipment in dry weather and significantly complicate movement during the rainy season, spring and autumn thaw. It can be cut by river beds, ravines and ravines, and have many lakes and swamps, which significantly limit the ability of troops to maneuver and reduce the pace of the offensive (Fig. 2).
Flat terrain is usually more favorable for organizing and conducting an offensive and less favorable for defense.
Hilly terrain characterized by the undulating nature of the earth's surface, forming unevenness (hills) with absolute heights of up to 500 m, relative elevations of 25 - 200 m and a predominant steepness of 2-3° (Fig. 3, 4). Hills are usually composed of hard rock, their tops and slopes are covered with a thick layer of loose rock. The depressions between the hills are wide, flat or closed basins.
Hilly terrain ensures the movement and deployment of troops hidden from enemy ground observation, facilitates the selection of places for firing positions of missile troops and artillery, and provides good conditions for the concentration of troops and military equipment. In general, it is favorable for both offense and defense.
Highlands represents areas of the earth's surface that are significantly elevated above the surrounding area (with absolute heights of 500 m or more) (Fig. 5). It is distinguished by complex and varied terrain and specific natural conditions. The main forms of relief are mountains and mountain ranges with steep slopes, often turning into cliffs and rocky cliffs, as well as hollows and gorges located between mountain ranges. Mountainous terrain is characterized by sharply rugged terrain, the presence of inaccessible areas, a sparse network of roads, a limited number of settlements, rapid river flows with sharp fluctuations in water levels, a variety of climatic conditions, and the predominance of rocky soils.
Combat operations in mountainous areas are considered as actions under special conditions. Troops often have to use mountain passes, making observation and firing, orientation and target designation difficult, at the same time it contributes to the secrecy of the location and movement of troops, facilitates the installation of ambushes and engineering barriers, and the organization of camouflage.
1.2 The essence of depicting relief on maps using contour lines.
Relief is the most important element of the terrain, determining its tactical properties.
The image of the relief on topographic maps gives a complete and fairly detailed idea of the unevenness of the earth's surface, the shape and relative position, elevations and absolute heights of terrain points, the prevailing steepness and length of the slopes.
1.3 Types of contour lines.
Horizontal- a closed curved line on a map, which corresponds to a contour on the ground, all points of which are located at the same height above sea level.
The following horizontal lines are distinguished:
- basic(solid) - the relief section corresponding to the height;
- thickened - every fifth main horizontal line; stands out for ease of reading the relief;
- additional horizontal lines(semi-horizontals) - drawn by a broken line at a height of the relief section equal to half the main one;
- auxiliary - are depicted by short broken thin lines at an arbitrary height.
Distance between two adjacent main horizontal heights are called the height of the relief section. The height of the relief section is indicated on each sheet of the map under its scale. For example: “Continuous horizontal lines are drawn every 10 meters.”
To make it easier to count contours when determining the heights of points on the map, all solid contours corresponding to the fifth multiple of the section height are drawn thickly and a number is placed on it indicating the height above sea level.
In order to quickly determine the nature of surface irregularities on maps when reading a map, special slope direction indicators are used - berg strokes- in the form of short lines placed on horizontal lines (perpendicular to them) in the direction of slopes. They are placed on the bends of horizontal lines in the most characteristic places, mainly at the tops of saddles or at the bottom of basins.
Additional contours(semi-horizontals) are used to display characteristic shapes and details of the relief (bends of slopes, peaks, saddles, etc.), if they are not expressed by the main horizontals. In addition, they are used to depict flat areas when the gaps between the main contour lines are very large (more than 3 - 4 cm on the map).
Auxiliary contours used to depict individual relief details (saucers in steppe regions, depressions, individual hillocks on flat terrain), which are not conveyed by the main or additional horizontal lines.
1.4 Representation of typical relief forms by horizontal lines.
Relief on topographic maps is depicted by curved closed lines connecting terrain points that have the same height above the level surface, taken as the beginning of the height reference. Such lines are called horizontals. The image of the relief with horizontal lines is supplemented by captions of absolute heights, characteristic points of the terrain, some horizontal lines, as well as numerical characteristics of relief details - height, depth or width (Fig. 7).
Some typical landforms on maps are displayed not only as main ones, but also as additional and auxiliary contour lines (Fig. 8).
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Rice. 8. Image of typical relief forms |
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2. Determination on the map of absolute heights and relative elevations of terrain points, ascents and descents, and steepness of slopes.
2.1. Determination of absolute heights and relative elevations of terrain points on the map
2.2. Identification on the map of ascents and descents along the route.
Rice. 10. Identification on the map of ascents and descents along the route (route profile).
Rice. 11. Determining the steepness of the slopes on the map |
Profile- a drawing depicting a section of the terrain with a vertical plane.
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2.3.Determining the steepness of the slopes on the map.
The steepness of the slope on the map is determined by its position - the distance between two adjacent main or thickened horizontal lines; the lower the laying, the steeper the slope\.
To determine the steepness of the slope, you need to measure the distance between the horizontal lines with a compass, find the corresponding segment on the location graph and read the number of degrees (Fig. 11).
On steep slopes, this distance is measured between thickened horizontal lines and the steepness of the slope is determined from the graph on the right.
3. Conventional signs of relief elements that are not expressed by horizontal lines.
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Ice cliffs (barriers) and fossil ice outcrops (8 - cliff height in meters) |
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Turfed ledges (edges) not expressed as horizontal lines |
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Coastal, historical, etc. ramparts that are not expressed by horizontal lines (3 - height in meters) |
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1) Dry riverbeds in one line (less than 5 m wide); |
Elevation marks |
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Command heights |
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Elevation marks at landmarks |
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Main passes, their heights and duration |
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Passes, their heights and duration |
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Karst and thermokarst sinkholes not shown on map scale |
Potholes that are not expressed on the map scale |
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Holes expressed at map scale |
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Outlier rocks with landmark value (10-height in meters) |
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Outlier rocks that have no landmark value |
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Dikes and other narrow, steep-walled ridges of hard rock (5 - ridge height in meters) |
Craters of mud volcanoes |
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Volcano craters not shown on map scale |
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Mounds and mounds not shown on the map scale |
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Mounds and mounds expressed on the map scale (5 - height in meters) |
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Clusters of stones |
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Separately lying stones (3 - height in meters) |
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Entrances to caves and grottoes |
Notes
Military topography
Military ecology
Military medical training
Engineering training
Fire training
Fundamentals of external and internal ballistics. Hand grenades. Grenade launchers and rocket-propelled anti-tank grenades.
Relief- a set of irregularities on the earth's surface.
The relief is made up of positive (convex) and negative (concave) shapes. The largest negative forms relief on Earth - ocean depressions, positive - continents. These are first order landforms. Landforms second order - mountains and plains (both on land and at the bottom of the oceans). The surface of the mountains and plains has a complex topography consisting of smaller forms.
Morphological structures- large elements of the relief of land, the bottom of oceans and seas, the leading role in the formation of which belongs to endogenous processes . The largest irregularities in the Earth's surface form continental protrusions and ocean trenches. The largest elements of land relief are flat-platform and mountainous areas.
Plain-platform areas include the 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, Turanian, North American plains), and high , raised by recent crustal movements to a height of 400-1000 m (Central Siberian Plateau, African-Arabian, Hindustan, significant parts of the Australian and South American plain regions).
Mountain areas occupy about 36% of the land area.
The underwater edge of the continent (about 14% of the Earth's surface) includes a generally shallow flat strip of continental shallows (shelf), a continental slope and a continental foot located at depths from 2500 to 6000 m. The continental slope and continental foot separate the continental protrusions, formed by the combination of land and shelf, from the main part of the ocean floor, called the ocean floor.
Island arc zone - transition zone of the ocean floor. The ocean floor itself (about 40% of the Earth's surface) is mostly occupied by deep-sea (average depth 3-4 thousand m) plains that correspond to oceanic platforms.
Morphosculptures- elements of the relief of the earth's surface, in the formation of which the leading role belongs exogenous processes . The work of rivers and temporary streams plays the greatest role in the formation of morphosculptures. They create widespread fluvial (erosive and accumulative) forms (river valleys, ravines, ravines, etc.). Glacial forms are widespread, caused by the activity of modern and ancient glaciers, especially the cover type (northern part of Eurasia and North America). They are represented by valleys, “ram’s foreheads” and “curly” rocks, moraine ridges, eskers, etc. In the vast territories of Asia and North America, where permafrost strata are common, various forms of frozen (cryogenic) relief are developed.
The most important landforms.
The largest landforms are continental ridges and ocean basins. Their distribution depends on the presence of a granite layer in the earth's crust.
The main landforms are mountains And plains . Approximately 60% of the land area is plains- vast areas of the earth's surface with relatively small (up to 200 m) fluctuations in heights. Based on absolute height, the plains are divided into lowlands (height 0-200 m), hills (200-500 m) and plateaus (above 500 m). According to 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, base, and top. Based on their appearance, mountains are divided into mountain ranges, chains, ridges and mountainous countries. Free-standing mountains are rare, representing either volcanoes or the remains of ancient destroyed mountains. Morphological mountain elements are: base (sole); slopes; peak or ridge (at ridges).
Foot 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 plain to the mountains, a strip is distinguished, which is called the foothills.
Slopes occupy most of the surface of the mountains and are extremely varied in appearance and steepness.
Vertex- the highest point of a mountain (mountain ranges), the pointed top of a mountain - a peak.
Mountain countries(mountain systems) - large mountain structures that consist of mountain ranges - linearly elongated mountain uplifts intersecting 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 mountain ranges is called a mountain valley.
Highlands- areas of mountainous countries, consisting of heavily destroyed ridges and high plains covered with destruction products.
Table “Relief and landforms. Mountains"
By height, mountains are divided into low (up to 1000 m), medium high (1000-2000 m), high (more than 2000 m). Based on their structure, folded, folded-block and block mountains are distinguished. Based on their geomorphological age, they distinguish between young, rejuvenated and revived mountains. Mountains of tectonic origin predominate on land, while mountains of volcanic origin predominate in the oceans.
Volcano(from Latin vulcanus - fire, flame) - a geological formation that arises above channels and cracks in the earth's crust, through which lava, ash, flammable gases, water vapor and rock fragments erupt onto the earth's surface. Highlight active, asleep Andextinct volcanoes. The volcano consists of four main parts : magma chamber, vent, cone and crater. There are about 600 volcanoes around the world. Most of them are located along plate boundaries, where red-hot magma rises from the Earth's interior and bursts to the surface.
Hello dear readers! Today I would like to talk about what the main landforms are. So shall we begin?
Relief(French relief, from the Latin relevo - I lift) is a set of irregularities of land, the bottom of seas and oceans, varying in contours, sizes, origins, age and history of development.
Consists of positive (convex) and negative (concave) shapes. The relief is formed mainly due to the long-term simultaneous influence of endogenous (internal) and exogenous (external) processes on the earth's surface.
The basic structure of the earth's relief is created by forces that lurk deep in the bowels of the Earth. Day after day, external processes influence it, tirelessly modifying it, cutting deep valleys and smoothing mountains.
Geomorphology – is the science of changes in the earth's topography. Geologists know that the old epithet “eternal mountains” is far from true.
Mountains (you can read more about mountains and their types) are not at all eternal, even though the geological time of their formation and destruction can be measured in hundreds of millions of years.
In the mid-1700s, the Industrial Revolution began. And from that moment on, human activity plays an important role in transforming the face of the Earth, which sometimes leads to unexpected results.
The continents acquired their current place on the planet and their appearance as a result of tectonics, that is, the movement of geological plates that form the solid outer shell of the Earth.
The movements that are the most recent in time occurred within the last 200 million years - this includes the connection of India with the rest of Asia (more about this part of the world) and the formation of the Atlantic Ocean depression.
Our planet has undergone many other changes throughout its history. The result of all these convergences and divergences of huge massifs, movements were numerous folds and faults of the earth's crust (more detailed information about the earth's crust), as well as powerful piles of rocks from which mountain systems were formed.
I will give you 3 striking examples of recent mountain building or orogenesis, as geologists call it. As a result of the collision of the European plate with the African one, the Alps appeared. When Asia collided with India, the Himalayas soared to the skies.
The Andes pushed upward the shift of the Antarctic Plate and the Nazca Plate, which together form part of the Pacific Trench, under the plate on which South America rests.
These mountain systems are all relatively young. Their sharp outlines did not have time to soften those chemical and physical processes that continue to change the earth’s appearance today.
Earthquakes cause enormous damage and rarely have long-term consequences. But volcanic activity injects fresh rocks into the earth’s crust from the depths of the mantle, often noticeably changing the usual appearance of the mountains.
Basic landforms.
Within the landmass, the earth's crust consists of a variety of tectonic structures that are more or less separated from one another, and differ from adjacent areas in geological structure, composition, origin and age of rocks.
Each tectonic structure is characterized by a certain history of movements of the earth’s crust, its intensity, regime, accumulation, manifestations of volcanism and other features.
The nature of the relief of the Earth's surface is closely related to these tectonic structures, and to the composition of the rocks that form them.
Therefore, the most important regions of the Earth with a uniform topography and a close history of their development - the so-called morphostructural regions - directly reflect the main tectonic structural elements of the earth's crust.
Processes on the earth's surface that affect the main forms of relief formed by internal, that is, endogenous processes, are also closely related to geological structures.
Individual details of large relief forms form external, or exogenous, processes, weakening or strengthening the action of endogenous forces.
These details of large morphostructures are called morphosculptures. Based on the scope of tectonic movements, their nature and activity, two groups of geological structures are distinguished: moving orogenic belts and persistent platforms.
They also differ in the thickness of the earth’s crust, its structure and the history of geological development. Their relief is also different - they have different morphostructures.
Flat areas of various types with small relief amplitudes are characteristic of platforms. The plains are divided into high (Brazilian - 400-1000 m absolute height, that is, altitude above sea level, African) and low (Russian Plain - 100-200 m absolute height, West Siberian Plain).
More than half of the total land area is occupied by the morphostructures of platform plains. Such plains are characterized by complex relief, the forms of which were formed during the destruction of heights and the redeposition of materials from their destruction.
Over large expanses of plains, as a rule, the same layers of rocks are exposed, and this causes the appearance of a homogeneous relief.
Among the platform plains, young and ancient areas are distinguished. Young platforms can sag and are more mobile. Ancient platforms are characterized by rigidity: they fall or rise as a single larger block.
4/5 of the surface of all land plains is part of such platforms. On the plains, endogenous processes manifest themselves in the form of weak vertical tectonic movements. The diversity of their relief is associated with surface processes.
Tectonic movements also influence us: in areas that rise, denudation, or destruction processes, predominate, and in areas that decline, accumulation, or accumulation, predominates.
External, or exogenous, processes are closely related to the climatic features of the area - the work of the wind (aeolian processes), erosion by flowing waters (erosion), the solvent action of groundwater (more about groundwater) (karst), washing away by rainwater (deluvial processes) and others .
The relief of mountainous countries corresponds to orogenic belts. Mountainous countries occupy more than a third of the land area. As a rule, the topography of these countries is complex, highly dissected and with large height amplitudes.
The different types of mountainous terrain depend on the rocks that compose them, on the height of the mountains, on the modern natural features of the area and on the geological history.
In mountainous countries with complex terrain, there are individual ridges, mountain ranges and various intermountain depressions. Mountains are formed by bent and tilted layers of rock.
Strongly bent into folds, crushed rocks alternate with igneous crystalline rocks in which there is no layering (basalt, liparite, granite, andesite, etc.).
Mountains arose in places on the earth's surface that were subject to intense tectonic uplift. This process was accompanied by the collapse of layers of sedimentary rocks. They tore, cracked, bent, compacted.
From the depths of the Earth, magma rose through gaps, which cooled at depth or poured out to the surface. Earthquakes occurred repeatedly.
The formation of large landforms - lowlands, plains, mountain ranges - is primarily associated with deep geological processes that have shaped the earth's surface throughout geological history.
During various exogenous processes, numerous and varied sculptural or small relief forms are formed - terraces, river valleys, karst chasms, etc...
For the practical activities of people, the study of large landforms of the Earth, their dynamics and various processes that change the surface of the Earth is very important.
Weathering of rocks.
The earth's crust consists of rocks. Softer substances, called soils, are also formed from them.
A process called weathering is the primary process that changes the appearance of rocks. It occurs under the influence of atmospheric processes.
There are 2 forms of weathering: chemical, in which it decomposes, and mechanical, in which it crumbles into pieces.
Rock formation occurs under high pressure. As a result of cooling, deep in the bowels of the Earth, molten magma forms volcanic rocks. And at the bottom of the seas, sedimentary rocks are formed from rock fragments, organic remains and silt deposits.
Exposure to weather.
Multilayer horizontal strata and cracks are often found in rocks. They eventually rise to the surface of the earth, where the pressure is much lower. The stone expands as the pressure decreases, and all the cracks in it accordingly.
Stone is easily exposed to weather factors due to naturally formed cracks, bedding and joints. For example, water that has frozen in a crack expands, pushing its edges apart. This process is called frost wedging.
The action of plant roots, which grow in cracks and, like wedges, push them apart, can be called mechanical weathering.
Chemical weathering occurs through the mediation of water. Water flowing over the surface or soaking into the rock carries chemicals into it. For example, oxygen in water reacts with iron contained in the rock.
Carbon dioxide absorbed from the air is present in rainwater. It forms carbonic acid. This weak acid dissolves limestone. With its help, the characteristic karst terrain, which gets its name from the area in Yugoslavia, is formed, as well as huge labyrinths of underground caves.
Many minerals dissolve with the help of water. And minerals, in turn, react with rocks and decompose them. Atmospheric salts and acids also play an important role in this process.
Erosion.
Erosion is the destruction of rocks by ice, sea, water flows or wind. Of all the processes that change the earth's appearance, we know it best.
River erosion is a combination of chemical and mechanical processes. Water not only moves rocks, and even huge boulders, but, as we have seen, dissolves their chemical components.
Rivers (more about rivers) erode floodplains, carrying soil far into the ocean. There it settles to the bottom, eventually turning into sedimentary rocks. The sea (you can talk about what the sea is) is constantly and tirelessly working to remake the coastline. In some places it builds up something, and in others it cuts something off.
The wind carries small particles like sand over incredibly long distances. For example, in southern England the wind brings sand from the Sahara from time to time, covering the roofs of houses and cars with a thin layer of reddish dust.
Impact of gravity.
Gravity during landslides causes hard rocks to slide down the slope, changing the terrain. As a result of weathering, rock fragments are formed, which make up the bulk of the landslide. Water acts as a lubricant, reducing friction between particles.
Landslides sometimes move slowly, but sometimes they rush at a speed of 100 m/sec or more. A creep is the slowest landslide. Such a landslide creeps only a few centimeters per year. And only after a few years, when trees, fences and walls bow under the pressure of the load-bearing earth, will it be possible to notice it.
A mudflow or mud flow can cause clay or soil (more about soil) to become oversaturated with water. It happens that for years the earth remains firmly in place, but a small earthquake is enough to bring it down the slope.
In a number of recent disasters, such as the eruption of Mount Pinatubo in the Philippines in June 1991, the main cause of casualties and destruction was mud flows that flooded many houses to the very roof.
As a result of avalanches (stone, snow, or both), similar disasters occur. A landslide or mud slide is the most common form of landslide.
On a steep bank, which is washed away by a river, where a layer of soil has broken away from the base, you can sometimes see traces of a landslide. A large landslide can lead to significant changes in the terrain.
Rockfalls are common on steep rocky slopes, deep gorges or mountains, especially in areas where eroded or soft rocks predominate.
The mass that has slid down forms a gentle slope at the foot of the mountain. Many mountain slopes are covered with long tongues of crushed stone scree.
Ice Ages.
Centuries-long climatic fluctuations also led to significant changes in the earth's topography.
During the last ice age, the polar ice caps held enormous masses of water. The northern cap extended far to the south of North America and the European continent.
Ice covered about 30% of the land on Earth (compared to only 10% today). Sea levels during the Ice Age (more information about the Ice Age) were about 80 meters lower than they are today.
The ice melted, and this led to colossal changes in the relief of the Earth's surface. For example, the following: the Bering Strait appeared between Alaska and Siberia, Great Britain and Ireland turned out to be islands that were separated from the whole of Europe, the land area between New Guinea and Australia went under water.
Glaciers.
In the ice-covered subpolar regions and in the highlands of the planet, there are glaciers (more about glaciers) - ice rivers. The glaciers of Antarctica and Greenland annually dump huge masses of ice into the ocean (you can learn more about what the ocean is), forming icebergs that pose a danger to shipping.
During the Ice Age, glaciers played a major role in giving the relief of the northern regions of the Earth a familiar appearance.
Crawling along the earth's surface with a giant planer, they carved out depressions in valleys and cut off mountains.
Under the weight of glaciers, old mountains, such as those in northern Scotland, have lost their sharp outlines and former height.
In many places, glaciers have completely cut away multi-meter layers of rock that had accumulated over millions of years.
The glacier, as it moves, captures a lot of rock fragments into the so-called accumulation area.
Not only stones fall there, but also water in the form of snow, which turns into ice and forms the body of the glacier.
Glacial sediments.
Having passed the boundary of the snow cover on the mountain slope, the glacier moves into the ablation zone, that is, gradual melting and erosion. The glacier, towards the end of this zone, begins to leave sediment of rocks on the ground. They are called moraines.
The place where the glacier finally melts and turns into an ordinary river is often designated as a terminal moraine.
Those places where long-vanished glaciers ended their existence can be found along such moraines.
Glaciers, like rivers, have a main channel and tributaries. The glacial tributary flows into the main channel from the side valley that it paved.
Usually its bottom is located above the bottom of the main channel. Glaciers that have completely melted leave behind a U-shaped main valley, as well as several side valleys, from which picturesque waterfalls cascade down.
You can often find such landscapes in the Alps. The clue to the driving force of the glacier lies in the presence of so-called erratic boulders. These are separate fragments of rock, different from the rocks of the glacial bed.
Lakes (more information about lakes) from a geological point of view are short-lived landforms. Over time, they are filled with sediment from the rivers that flow into them, their banks are destroyed and the water drains away.
Glaciers have formed countless lakes in North America, Europe (you can read more about this part of the world) and Asia by carving out hollows in rocks or blocking valleys with terminal moraines. There are a great many glacial lakes in Finland and Canada.
For example, other lakes, such as Crater Lake in Oregon (USA) (more about this country), are formed in the craters of extinct volcanoes as they fill with water.
Siberian Baikal and the Dead Sea, between Jordan and Israel, arose in deep cracks in the earth's crust that were formed by prehistoric earthquakes.
Anthropogenic landforms.
Through the work of builders and engineers, new relief forms are created. The Netherlands is a great example of this. The Dutch proudly say that they created their country with their own hands.
They were able to recapture about 40% of the territory from the sea, thanks to a powerful system of dams and canals. The need for hydroelectric power and fresh water has forced people to build a considerable number of artificial lakes or reservoirs.
In the state of Nevada (USA) there is Lake Mead, it was formed as a result of the damming of the Colorado River by the Hoover Dam.
After the construction of the high-rise Aswan Dam on the Nile, Lake Nasser appeared in 1968 (near the border of Sudan with Egypt).
The main purpose of this dam was to regularly provide water for agriculture and regulate annual floods.
Egypt has always suffered from changes in the level of Nile floods, and it was decided that a dam would help solve this centuries-old problem.
The other side of the coin.
But the Aswan Dam is a striking example of the fact that nature is not to be trifled with: it will not tolerate rash actions.
The whole problem is that this dam blocks the annual deposits of fresh silt that fertilized the agricultural land, and in fact, which formed the Delta.
Now, silt is accumulating behind the wall of the Aswan High Dam, thereby threatening the existence of Lake Nasser. Significant changes can be expected in the Egyptian terrain.
The appearance of the Earth is given new features by railways and highways built by man, with their cut slopes and embankments, as well as mine waste heaps, which have long disfigured the landscape in some industrial countries.
Erosion is caused by cutting down trees and other plants (their root systems hold together mobile soils).
It was these ill-considered human actions that led, in the mid-1930s, to the emergence of the Dust Bowl on the Great Plains, and today they threaten the Amazon basin in South America.
Well, dear friends, that’s all for now. But expect new articles soon 😉 I hope that this article helped you understand what types of relief there are.
The structure of the earth's surface is very diverse. However, you can always find forms that are similar in appearance and origin, which are naturally repeated in a certain territory and are typical for it. Such combinations of forms of the earth's surface that are homogeneous in appearance and origin are called relief types.
The main external features of the relief: the nature of its forms, height above sea level and relative height or depth of dissection. Based on these indicators, the terrain is distinguished as flat, hilly and mountainous.
Plains are areas in which the fluctuations in heights and surface slopes are very small.
Plains are: inclined– with a slight tilt to one side; concave– with a slope from all sides towards the middle; And wavy- with fluctuations in slope, now in one direction, now in the other, and alternation of flat hills and surface elevations.
Based on altitude above sea level, the following plains are conventionally distinguished:
– low-lying– with an absolute height of up to 200 m;
– sublime(plateau) – with heights up to 500 m;
– upland– with altitudes over 500 m.
Hilly called relief with relative heights of up to 200 m. Hills often have the shape of elongated ridges or ridges and, accordingly, form a ridge or hilly relief. Depending on the height of the hills, the relief is distinguished large hilly, medium hilly And small hilly.
Mountain called relief, the unevenness of which exceeds a relative height of 200 m. Based on shape, absolute and relative height, mountainous terrain is divided into the following types: alpine(alpine) type, mid-mountain And low mountain types.
The morphology of flat, hilly and mountainous terrain is far from being exhausted by the given characteristics. It is largely determined by the peculiarities of the geomorphological structure of the territory and, above all, by the conditions of occurrence of rocks.
The most characteristic are the following four forms of occurrence of layers:
undisturbed horizontal position;
slightly disturbed horizontal bedding - the layers have a gentle and conformable dip;
folded bedding - layers are crumpled into folds;
fold-fault occurrence - layers are folded and displaced relative to each other.
The nature of the occurrence of layers is clearly expressed in the forms of relief during their erosional dissection and, especially in those cases where there is an alternation of layers of different densities and different resistance to erosion.
Such specific forms of relief, caused by the occurrence of layers of different densities, i.e. geological structure are called structural.
In conditions of undisturbed horizontal occurrence of layers, watershed hills (plateaus, plateaus) are formed during erosional dissection. The slopes of the hill are often stepped, each step corresponds to the exit of a solid layer to the surface.
In conditions of weakly disturbed layers during erosional dissection, characteristic structural forms of relief are formed in places where dense layers emerge, called cuestas. They are usually separated by valleys embedded in softer, more easily eroded rocks. Cuestas usually have an asymmetrical structure.
Under conditions of folded occurrence, with alternation of regular folds of convex (anticline) and concave (syncline) shapes, erosional dissection most often forms anticlinal ridges with a wide rounded ridge, monoclinal ridges with a sharp ridge and an asymmetrical transverse profile; longitudinal synclinal valleys with a symmetrical transverse profile; asymmetric monoclinal valleys.
In conditions of fold-fault occurrence of layers, in addition to the listed relief forms, there are also forms that were formed as a result of vertical displacements of layers (uplifts and subsidences) with gaps between them. Are formed horsts and grabens. The latter in the mountains are usually occupied by rivers and lakes, contoured by small steps and slopes with ledges.
Thus, the geological structure of the area determines the formation of various and widespread structural forms characteristic of different types of relief. It follows from this that even a general idea of the geological structure of the area provides significant assistance in assessing the image of the relief on a topographic map.
The relief of the earth's surface is determined not only by the movement of the earth's crust (tectonics) and the nature of the occurrence of layers, but also by the activity of the second group of factors - external (exogenous). The latter significantly transform the primary (tectonic) forms and greatly complicate their structure.
These factors include the activity of water flows (temporary and permanent) of the seas, lakes, glaciers, melted glacial waters, groundwater, wind and others. The activity of these factors is manifested in the fact that in some places the rocks lying on the surface of the Earth are destroyed, eroded and carried from a given area to another, where they are deposited and, accumulating, often reach great thickness, thus passing through the stages of hypergenesis, sedimentogenesis and diagenesis.
Destruction processes are called erosion(or in a broader sense - denudation), and accumulation - accumulation. In the process of erosion or denudation, the relief is dismembered, the elevations are more and more destroyed and become leveled over time (the process peneplainization). This type of relief is called erosional or denudation.
During the process of accumulation, depressions are filled with loose rocks transported from the outside, and a predominantly flat relief, called accumulative, is formed.
In accordance with which factor (agent) produces erosion or accumulation, forms are distinguished: water-erosive or water-accumulative, glacial-erosive and glacial-accumulative, etc.
Where the activity of surface and groundwater occurs in soluble rocks (limestones, dolomites, etc.), peculiar voids are formed (karst landforms).
The flat, hilly and mountainous reliefs described above can be of different origins, and therefore have different shapes.
Plains in their origin are:
– marine accumulative– formed as a result of transgression of the ocean floor;
– river accumulative– formed as a result of tectonic uplifts and subsidences;
– water-glacial accumulative– formed as a result of melting glaciers;
– lacustrine-accumulative – areas of flat bottoms of former lakes;
– upland accumulative – formed as a result of the destruction and accumulation of materials;
– volcanic– the result of the activity and destruction of volcanoes;
– residual – the result of denudation of the earth’s surface;
– abrasion – the result of exposure to sea waves.
Hilly relief can be of different origins: water erosion; glacial-erosive; wind and volcanic.
Mountain relief is of different origins: erosional-tectonic, erosional (erosion-folded and erosional-blocky) and volcanic.
