What is relief. The surface of the earth's crust is uneven. In some parts of it there are mountains or plains, in others there are deep depressions of the oceans. It is thanks to such irregularities that land and life on it exist on Earth. If the surface of the planet were flat, it would be covered by an ocean 2450 m deep!

All irregularities in the surface of the land and the bottom of the seas and oceans are called relief.

Landforms. Any unevenness of the Earth's surface is a form of relief, which has a height, area and shape. Convex relief forms are mountains, hills, hills on land and the bottom of the oceans, concave ones are basins of seas and lakes, ravines, beams.

The largest landforms are the continents and the depressions of the oceans, their existence is associated with the structure of the earth's crust. Mountains and plains also belong to the largest forms. Large forms are ridges and depressions in the mountains, lowlands and uplands on the plains. Medium and small forms are represented by ravines, hills, bumps, mounds and other irregularities.

The relief of the Earth's surface is very complex, since smaller forms are superimposed in various combinations on larger ones. This is how the original and unique appearance of the surface of every corner of our planet arises.

Causes of relief diversity. The relief is very diverse, because the surface of the Earth is simultaneously affected by internal (deep) and external forces. The source of energy for internal forces is the heat generated in the bowels of the planet, and for external forces - solar energy.

Internal forces lower and raise, stretch and compress the surface, crush rocks into folds. Thanks to these forces, the largest and many large landforms arise. Among the internal forces of the Earth, slow movements of the earth's crust, earthquakes and volcanism play the greatest role. External forces - water, wind, glaciers, man - create medium and small relief irregularities. All forms - both large and small - change their outlines over time. Therefore, any physical map is just a snapshot of an ever-changing terrain.

The relief plays a huge role in shaping the nature of various regions of the Earth. It affects the temperature, the amount of moisture, vegetation and wildlife. It also affects a person's life. People settle mainly on the plains, because it is easier to farm on them.

How relief is depicted on plans and maps. According to plans and physical maps, it is possible to describe in detail the terrain. To do this, they have marks of heights and depths. These marks show the height or depth of points on the earth's surface in relation to the level of the World Ocean. It is the same everywhere, since all seas and oceans communicate with each other. The level of the ocean (or sea) is taken as 0 m.

The height of a point above ocean (sea) level is called absolute height.

Marks of heights and depths are indicated by dots, near which a number is affixed. It shows height or depth in meters.

The absolute height of Moscow is 120 m, and St. Petersburg is 3 m. This means that the territory where Moscow is located is 120 m above sea level, and St. Petersburg is 3 m above sea level. Some points on the land surface are below sea level. seas. In this case, a “-” sign is placed before the height mark. For example, -405, -28.

On the physical map in the atlas, determine the absolute height of Mount Chomolungma (Everest) in the Himalayas.

Another way to depict the terrain is with the help of contour lines.

Contours are lines on plans and maps connecting points with the same absolute height.

Horizontals and their absolute height are applied in brown (Fig. 45, a). Contours have short dashes - bergstrokes. They are always directed down the slope. In places where the horizontals converge, the slopes are steeper.

It is possible to determine the height of points on the earth's surface not only in relation to sea level, but also in relation to each other.

Rice. 45. Relief image: a - contour lines; b - horizontal lines with layered coloring

Consider the drawing. Find the contours and determine which shape - convex or concave - is shown on the map. Which slopes of this form are steeper and which ones are more gentle?

The height of one point on the surface relative to another is called the relative height.

If the top of the hill rises above sea level by 150 m, and above the surrounding plain by 20 m, then 150 m is the absolute height of the hill, and 20 m is its relative height.

Rice. 46. ​​Absolute and relative hill height

Look at the picture and calculate the relative height of the hill.

A visual representation of the relief on physical maps is provided by layer-by-layer coloring (Fig. 45, b). It emphasizes the steps of the relief with different absolute heights and depths. Between the contour lines 0 m (sea level) and 200 m, the land is colored green. Territories with heights of more than 200 m are painted with different shades of brown paint - the higher, the darker. In the same way, only in blue and blue, they indicate the depths of the seas and oceans. Layered coloring is deciphered by a special scale of heights and depths, which is available on any physical map.

Questions and tasks

1. How are landforms classified according to size? Give examples.
2. What is absolute and relative height?
3. Why is the relief on Earth so diverse?
4. Using the height and depth scale, determine which heights prevail in Africa and which depths prevail in the Pacific Ocean.

There are many natural components that the geography of the Earth studies in detail. Relief is one of them. Our planet is beautiful and unique! Its appearance is the result of a whole complex of various processes.

Why is the Earth's relief so diverse? We will try to answer this question as clearly as possible in this article.

Why is the relief varied? The main reason

Deep underwater gorges and the highest pointed peaks, huge flat plateaus and marshy depressions, wide endless plains and hilly heights - all this can be found on the surface of our wonderful planet. Let's try to answer a simple question: why is it so diverse?

The main reason for this diversity is the mutual influence of internal (endogenous) and external influences on the surface of the planet. In turn, the catalyst for these processes, ultimately, is the energy of the Sun.

The essence of endogenous processes is the displacement of the earth's crust, which can be both vertical and horizontal. These movements not only change the general structure of the earth's crust, but also create new landforms.

While endogenous processes form the relief of the planet (act as builders), exogenous processes hone and decorate it, being some kind of "sculptors" of earthly forms. They act on the outside, through the weathering of rocks, the work of surface and underground waters, wind and gravity. It is important to note that these processes have occurred and are constantly occurring on our planet.

Denudation and accumulation are the main processes of relief formation

Now that you already know, you can describe in more detail those processes that are guilty of this. We will talk about denudation and accumulation, which are connected dialectically.

Denudation is understood as the totality of all processes that are aimed at the destruction of rocks. The main driving force of denudation is gravity (universal gravity). Mountain landslides, mudflows, the movement of large glaciers and the flow of rivers - all this, one way or another, is connected with it. Denudation seeks to level the relief of the territory as much as possible.

Accumulation is the opposite process, which consists in the accumulation of rock particles in certain areas of the Earth's surface. Nevertheless, denudation and accumulation are closely and inextricably linked. As a result of accumulation processes, plains, terraces, deltas, dunes, coastal spits, and the like are formed on the Earth's surface.

Genetic landform types

As a result of endogenous processes, the following types of relief are formed:

• tectonic;
• volcanic.

Among the main types of relief of exogenous origin (genesis) should be distinguished:

• fluvial relief (river valleys, beams, ravines, gullies, etc.);
• glacial (eskers, moraine ridges and plains, kams, etc.);
• coastal or abrasive (marches, spits, abrasion shores, beaches, etc.);
• gravitational (landslides, landslides, screes);
• eolian (dunes, dunes);
• karst (caves, funnels, karst mines);
• suffusion (pods, "steppe saucers");
• anthropogenic (relief created by human activity: quarries, mines, embankments, waste heaps, dams, etc.).

All these numerous landforms create that motley and unique pattern of our planet.

Finally

After reading our article, the question of why the Earth's relief is very diverse will no longer be able to drive you into a dead end. The appearance, the drawing of our planet, was created over millions of years. The formation of the main forms of the earth's relief is based on various processes, such as endogenous (internal) and exogenous (external).

When I was little, I often asked my parents: "Why don't we have mountains?" or "Why don't we live near the sea?" There was no way for me to understand why there are many different landforms on one territory, and on the other - a flat plain and no hills, as we had. Then I grew up, went to school and, of course, found all the answers to my questions. If you're interested, I'll be happy to tell you.

What is relief

Relief is the totality of all the irregularities of the earth's surface. both on land and underwater. relief happens three forms:

• convex(the mountains);
• concave(hollows);
• flat(plains).

In geography, there are two main landforms: mountains and plains. Plains- part of the earth's surface slight fluctuation heights. The mountains- part of the earth's surface rise significantly above ground level.

How did relief come about?

Now let's find out how all these irregularities of the earth's crust arose. The relief that we see today originated millions of years ago, but it still continues to change. What influences the formation of relief? Scientists have identified two main factors:internal and inexternal.

Internal(endogenous) factors are processes that occur in the Earth. The earth's crust is divided into several lithospheric plates that lie on the mantle. The upper part of the mantle is a hot substance, and therefore the lithospheric plates on it are constantly moving relative to each other. In some places they move apart and form depressions and gutters, in others close up, fold like an "accordion" and form mountain ranges. It is at the junctions of lithospheric plates that all large landforms are located, and the epicenters of all earthquakes are located. The plains formed in the centers of the lithospheric plates.

But the formation of the current landforms is influenced, for the most part, external (exogenous) factors. These processes for the formation of relief occur due to:

• temperature changes;
• wind action;
• action of water;
• movement of glaciers;
• human activities.

One of the main external factors is weathering. It can be physical and chemical. Cause physical weathering are temperature differences, due to which cracks form in rocks. Cause chemical weathering contains water and substances soluble in it. They also erode soil and rocks.

There are two main factors that influence the formation of different forms of the surface, say, on different sides of the earth's crust. Thus, many influences have been shared, which explain why the Earth's relief is very diverse. But first, let's figure out what the concept of "relief" carries.

The term "relief" and its meaning

This word is of French origin, or some sources explain it by translating the classics from Latin, and it is used for several industries - construction, art. But in all senses, its meaning is the same - it is a set of irregularities. For sculpture, these irregularities are artificially created by man; in construction, the human hand also makes efforts to create one form or another. But on a planetary scale, man occupies the third place of honor among the forces that influence why the Earth's relief is very diverse.

Relief groups, or what categories do certain formations belong to

To begin with, let's remember what forms there are on the earth's surface. All types of land relief are divided into positive and negative. The positive ones include any elevations above the imaginary horizontal plane, the negative - on the contrary, below it. That is, the first group includes mountains, hills, mounds, plateaus. To the second group - depressions, crevices, valleys, beams. And now more about the diversity of the Earth's relief, namely, what creates it.

First place - internal forces of the earth

These forces have a scientific name - endogenous. What is their impact?

Initially, the relief of the entire surface of the Earth was subjected to intense influence of internal forces. Earthquakes, volcanic eruptions are their most obvious manifestations, which, if you carefully study the studies of anthropologists, previously very intensively changed the landscapes of the Earth, and even now quite often subject the earth's crust to collapse, and, consequently, to new formation of the surface.
In addition, lithospheric plates are in constant slow motion, which also affects the creation of relief. Why is the Earth's relief diverse in terms of internal forces? Because in connection with all the processes under the earth's crust, its changes occur outside. This is how mountains, ocean depressions, plains and uplands appear. Lithospheric plates (seven large and dozens of small ones) move, collide, move apart, forming the highest mountains (Alps, Himalayas, etc.) or deep depressions on land and under water (the Mariana Trench is the most striking example).

What we are seeing now is the result of plate movements over many millions or even billions of years, corrected by the following type of impact on the relief.

Second place - external forces of the earth

The scientific name for these forces is exogenous. Why is the Earth's topography so diverse due to these influences?

The sun, wind, precipitation - all these everyday phenomena are directly related to the formation of one form or another of the surface. All formations that have arisen under the influence of internal forces begin to transform also because of them. So, the sun heats the mountain peaks. Substances, minerals, which are present in the composition of mountains, have different thermal conductivity and other physical properties. As a result, as they expand unevenly, they lose strong bonds with each other, stratifying, dismembering and, in the end, turning into sand. And if we add to this the effect of water, which in warm time penetrates into all the smallest cracks, and when the temperature drops, it turns into ice, which, accordingly, expands and pushes the cracks apart, aggravating them, this eventually leads to the same destruction. That is why the relief of the Earth is very diverse, because these processes occur every minute throughout the Earth.

Do not forget about the effect of rivers, lakes, oceans on the adjacent zones. So, the coasts can both increase and decrease every year, depending on the direction of the waters. It may be subtle, but it still happens.

Third place - man

It is classified as an external force, but I would like to single out this influence in a separate category. The development of technology gives a person an equal opportunity to go into space and climb deep into the earth's crust (the main thing is that the funding is good, space is still winning here). The extraction of resources (oil, gas, ores, rock salt, other minerals) is increasingly changing the once familiar landscapes. Drainage of swamps, deforestation, creation of reservoirs, and other influences on the diversity of the Earth's relief can change the microclimate of certain areas, forcing animals to look for completely different habitats. And this happens everywhere, and it is far from always possible to call this influence useful. If in the case of the wind it is impossible to call him to account - this is an element, then a person, as a rational being, it would seem, should understand the destructiveness of his actions, and make reasonable decisions. It would seem that.

And what is the result

As a result, it turns out that the modern relief of the Earth is the result of the interaction of all these forces, and they continue to act daily, continuously, and even right now, while your eyes are reading this long phrase, slowly but surely changing the outlines of our planet. And perhaps, after a few hundred years, descendants will be very surprised to find an old relief map, for example, for 1995, what the world was like at that time.