Every change always requires some effort. Any change will not happen without some impact. And an obvious example of this is our home planet, which was formed under the influence of various factors over billions of years. It is also important that the constant processes of Earth change are the result of not only external forces, but also internal ones, those that are hidden deep in the bowels of the geosphere.
And if in two or three decades the appearance of our planet may well change beyond recognition, then obviously it will not be superfluous to understand the processes whose influence led to this.
Change from within
Heights and hollows, unevenness and roughness, as well as many other features of the land relief - all this is constantly updated, collapses and is formed by powerful internal forces. Most often, their manifestation remains outside our field of vision. However, even right at this moment, the Earth is gradually undergoing one or another change, which in the long term will become much more significant.
Ever since I wasThe ancient Romans and Greeks noticed the uplift and subsidence of various sections of the lithosphere, causing all changes in the outlines of the seas, land and oceans. Many years of scientific research using various technologies and devices fully confirm this.
Growth of mountain ranges
Slow movement of individual sections of the earth's crust gradually leads to their overlap. Colliding in horizontal movement, their thicknesses bend, crumple and transform into folds of different scales and steepness. In total, science distinguishes two types of mountain-building movements (orogeny):
- Blowing of layers - forms both convex folds (mountain ranges) and concave ones (depressions in mountain ranges). It is from this that the name of the folded mountains came from, which gradually collapse over time, leaving behind only the base. Plains are formed on it.
- Fracture of layers - rock masses can not only be crushed into folds, but also be subjected to faults. In this way, folded blocky (or simply blocky) mountains are formed: skids, grabens, horsts and their other components arise when the sections of the earth's crust are vertically displaced (upward/lowering down) relative to each other.
But the inner strength of the Earth is capable of not only crushing plains into mountains and destroying the former outlines of hills. The movements of the lithospheric plates also generate earthquakes and volcanic eruptions, which are often accompanied by monstrous devastation and human deaths.
Breathing from under the bowels
It's even hard to imagine that the concept of "volcano" familiar to every person in ancient times had a much more formidable connotation. At first, the true reason for such a phenomenon, according to custom, was associated with the disfavor of the gods. The flows of magma erupted from the depths were considered a severe punishment from above for the faults of mortals. Catastrophic losses due to volcanic eruptions have been known since the dawn of our era. Thus, for example, the majestic Roman city of Pompeii was wiped off the face of planet Earth. The strength of the planet at that moment was manifested by the crushing power of the now widely known volcano Vesuvius. By the way, the authorship of this term is historically assigned to the ancient Romans. So they called their god of fire.
For modern man, a volcano is a cone-shaped hill above cracks in the crust. Through them, magma erupts to the surface of the earth, the sea or ocean floor, along with gases and rock fragments. In the center of such a formation is a crater (translated from Greek - "bowl"), through which the ejection occurs. When solidified, the magma turns into lava and forms the outlines of the volcano itself. However, even on the slopes of this cone, cracks often appear, thereby forming parasitic craters.
Quite often, eruptions are accompanied by earthquakes. But the greatest danger to all living things is precisely emissions from the bowels of the Earth. The release of gases from magma occurs extremely quickly, so powerful explosions subsequently -commonplace.
By the type of action, volcanoes are divided into several types:
- Active - those about the last eruption of which there is documentary information. The most famous among them: Vesuvius (Italy), Popocatepetl (Mexico), Etna (Spain).
- Potentially active - they erupt extremely rarely (once every several thousand years).
- Extinct - volcanoes have this status, the last eruptions of which have not been documented.
The impact of earthquakes
Shifts of rocks often provoke fast and strong fluctuations of the earth's crust. Most often this occurs in the region of high mountains - these areas continue to continuously form to this day.
The place where shifts originate in the depths of the earth's crust is called the hypocenter (center). Waves propagate from it, which create vibrations. The point on the surface of the earth, directly below which the focus is located - the epicenter. This is where the strongest tremors are observed. As they move further away from this point, they gradually fade away.
The science of seismology, which studies the phenomenon of earthquakes, distinguishes three main types of earthquakes:
- Tectonic - the main mountain-forming factor. Occurs as a result of collisions between oceanic and continental platforms.
- Volcanic - arise as a result of flows of red-hot lava and gases from under the earth's interior. Usually they are quite weak, although they can last for several weeks. Most often, they are harbingers of volcanic eruptions, which is fraught with much more serious consequences.
- landslide - occur as a result of the collapse of the upper layers of the earth, covering voids.
The strength of earthquakes is determined on a ten-point Richter scale using seismological instruments. And the greater the amplitude of the wave that occurs on the earth's surface, the more tangible the damage will be. The weakest earthquakes, measured at 1-4 points, can be ignored. They are recorded only by special sensitive seismological instruments. For people, they manifest themselves as a maximum in the form of trembling glasses or slightly moving objects. For the most part, they are completely invisible to the eye.
In turn, fluctuations of 5-7 points may well lead to various damages, albeit minor ones. Stronger earthquakes are already a serious threat, leaving behind destroyed buildings, almost completely destroyed infrastructure and human losses.
Every year, seismologists register about 500 thousand vibrations of the earth's crust. Fortunately, only a fifth of this number is actually felt by people, and only 1000 of them cause real damage.
More about what affects our common home from the outside
Continuously changing the relief of the planet, the internal force of the Earth does not remain the only formative element. Numerous external factors are also directly involved in this process.
Destroying numerous irregularities and filling underground depressions, they make a tangible contribution to the process of continuous change in the Earth's surface. Worth payingPlease note that in addition to flowing waters, devastating winds and the action of gravity, we also directly affect our own planet.
Changed by the wind
The destruction and transformation of rocks mainly occurs under the influence of weathering. It does not create new relief forms, but breaks down solid materials into a friable state.
In open spaces, where there are no forests and other obstacles, sand and clay particles can move considerable distances with the help of winds. Subsequently, their accumulations form aeolian landforms (the term comes from the name of the ancient Greek god Aeolus, the lord of the winds).
Example - sand hills. Barchans in deserts are created exclusively by the action of the wind. In some cases, their height reaches hundreds of meters.
Sedimentary mountain deposits consisting of dusty particles can accumulate in the same way. They are greyish-yellow in color and are called loess.
It should be remembered that, moving at high speed, various particles not only accumulate into new formations, but also gradually destroy the relief encountered on their way.
There are four types of rock weathering:
- Chemical - consists in chemical reactions between minerals and the environment (water, oxygen, carbon dioxide). As a result, rocks undergo destruction, their chemical component undergoes changes with the further formation of new ones.minerals and compounds.
- Physical - causes mechanical disintegration of rocks under the influence of a number of factors. First of all, physical weathering occurs with significant temperature fluctuations during the day. Winds, along with earthquakes, volcanic eruptions and mudflows, are likewise factors in physical weathering.
- Biological - is carried out with the participation of living organisms, whose activity leads to the creation of a qualitatively new formation - the soil. The influence of animals and plants is manifested in mechanical processes: crushing rocks with roots and hooves, digging holes, etc. Microorganisms play a particularly large role in biological weathering.
- Radiation or solar weathering. A characteristic example of the destruction of rocks under such impact is the lunar regolith. Along with this, radiation weathering also affects the previously listed three species.
All these types of weathering often appear in combination, combined in various variations. However, different climatic conditions also affect one's dominance. For example, in places with a dry climate and in high mountainous areas, physical weathering is often encountered. And for areas with a cold climate, where temperatures often fluctuate to 0 degrees Celsius, not only frost weathering is characteristic, but also organic, coupled with chemical.
Gravity effect
No list of the external forces of our planet will be complete without mentioning the fundamental interaction of all materialbodies is the gravitational force of the Earth.
Destroyed by numerous natural and artificial factors, rocks are always subject to movement from elevated areas of soil to lower ones. This is how landslides and screes are generated, mudflows and landslides also occur. The gravitational force of the Earth at first glance may seem like something invisible against the background of powerful and dangerous manifestations of other external factors. However, all their impact on the relief of our planet would simply be leveled without universal gravitation.
Let's take a closer look at the effects of gravity. Under the conditions of our planet, the weight of any material body is equal to the force of gravity of the Earth. In classical mechanics, this interaction describes Newton's law of universal gravitation, known to everyone from school. According to him, the F of gravity is equal to the product of m and g, where m is the mass of the object, and g is the acceleration due to gravity (always equal to 10). At the same time, the force of gravity of the Earth's surface affects all bodies located both directly on it and near it. If the body is affected exclusively by gravitational attraction (and all other forces are mutually balanced), it is subject to free fall. But for all their ideality, such conditions, where the forces acting on the body near the Earth's surface, in fact, are leveled, are characteristic of vacuum. In everyday reality, you have to face a completely different situation. For example, a falling object in the air is also affected by the amount of air resistance. And even though the force of gravity of the Earthwill be much stronger, this flight will no longer be truly free by definition.
It is interesting that the effect of gravity exists not only in the conditions of our planet, but also at the level of our solar system as a whole. For example, what attracts the moon more strongly? Earth or Sun? Without a degree in astronomy, many will probably be surprised by the answer.
Because the force of attraction of the satellite by the Earth is about 2.5 times less than that of the sun! It would be reasonable to think about how the heavenly body does not tear the Moon away from our planet with such a strong impact? Indeed, in this regard, the value, which is equal to the force of gravity of the Earth in relation to the satellite, is significantly inferior to that of the Sun. Fortunately, science can answer this question as well.
Theoretical cosmonautics uses several concepts for such cases:
- Scope of the body M1 - the surrounding space around the object M1, within which the object m moves;
- The body m is an object freely moving in the scope of the object M1;
- The M2 body is an object that disturbs this movement.
It would seem that the gravitational force should be decisive. The Earth attracts the Moon much weaker than the Sun, but there is another aspect that has the final effect.
The whole point is that M2 tends to break the gravitational connection between objects m and M1 by endowing them with different accelerations. The value of this parameter directly depends on the distance of objects to M2. However, the difference between the accelerations given by the body M2 on m and M1 will be less than the difference between the accelerations m and M1 directly in the gravitational field of the latter. This nuance is the reason why M2 is unable to separate m from M1.
Let's imagine a similar situation with the Earth (M1), the Sun (M2) and the Moon (m). The difference between the accelerations that the Sun creates in relation to the Moon and the Earth is 90 times less than the average acceleration that is characteristic of the Moon in relation to the Earth's sphere of action (its diameter is 1 million km, the distance between the Moon and the Earth is 0.38 million kilometers). The decisive role is played not by the force with which the Earth attracts the Moon, but by the large difference in accelerations between them. Thanks to this, the Sun can only deform the Moon's orbit, but not tear it away from our planet.
Let's go even further: the effect of gravity is to varying degrees characteristic of other objects in our solar system. What effect does it have, given that gravity on Earth is vastly different from other planets?
This will affect not only the movement of rocks and the formation of new landforms, but also their weight. Be sure to note that this parameter is determined by the magnitude of the force of attraction. It is directly proportional to the mass of the planet in question and inversely proportional to the square of its own radius.
If our Earth were not flattened at the poles and elongated near the Equator, the weight of any body on the entire surface of the planet would be the same. But we do not live on a perfect ball, and the equatorial radius is longerpolar about 21 km. Therefore, the weight of the same object will be heavier at the poles and lightest at the equator. But even at these two points, the force of gravity on Earth differs slightly. The tiny difference in weight of the same object can only be measured with a spring balance.
And a completely different situation will develop in the conditions of other planets. For clarity, let's look at Mars. The mass of the red planet is 9.31 times less than the earth's, and the radius is 1.88 times less. The first factor, respectively, should reduce the force of gravity on Mars in comparison with our planet by 9.31 times. At the same time, the second factor increases it by 3.53 times (1.88 squared). As a result, the gravity on Mars is about a third of that on Earth (3.53: 9.31=0.38). Accordingly, a rock with a mass of 100 kg on Earth will weigh exactly 38 kg on Mars.
Given what gravity is inherent in the Earth, it can be compared in one row between Uranus and Venus (whose gravity is 0.9 times less than Earth's) and Neptune and Jupiter (their gravity is greater than ours by 1.14 and 2.3 times, respectively). Pluto was noted to have the least effect of gravity - 15.5 times less than terrestrial conditions. But the strongest attraction is fixed on the Sun. It exceeds ours by 28 times. In other words, a body weighing 70 kg on Earth would weigh up to approximately 2 tons there.
Water will flow under the lying layer
Another important creator and simultaneously destroyer of reliefs is moving water. Its flows form wide river valleys, canyons and gorges with their movement. However, even small amountswhen slowly moving, they are able to form a ravine-beam relief in place of the plains.
Punching your way through any obstacles is not the only side of the influence of the currents. This external force also acts as a transporter of rock fragments. This is how various relief formations are formed (for example, flat plains and growths along rivers).
In particular, the influence of flowing water affects easily soluble rocks (limestone, chalk, gypsum, rock s alt) located close to land. Rivers gradually remove them from their path, rushing into the depths of the earth's interior. This phenomenon is called karst, as a result of which new landforms are formed. Caves and funnels, stalactites and stalagmites, abysses and underground reservoirs - all this is the result of a long and powerful activity of water masses.
Ice Factor
Along with flowing waters, glaciers are no less involved in the destruction, transportation and deposition of rocks. Thus creating new landforms, they smooth out the rocks, form stained hills, ridges and basins. The latter are often filled with water, turning into glacial lakes.
The destruction of rocks by means of glaciers is called exaration (glacial erosion). When penetrating into river valleys, ice exposes their beds and walls to strong pressure. Loose particles are torn off, some of them freeze and thereby contribute to the expansion of the walls of the bottom depth. As a result, river valleys take the form ofthe least resistance for the advancement of ice is a trough-shaped profile. Or, according to their scientific name, glacial troughs.
The melting of glaciers contributes to the creation of sandra - flat formations consisting of particles of sand accumulated in frozen water.
We are the outer force of the Earth
Given the internal forces acting on the Earth, and external factors, it's time to mention you and me - those who have been bringing tremendous changes to the life of the planet for more than a decade.
All landforms created by man are called anthropogenic (from Greek anthropos - man, genesisum - origin, and Latin factor - business). Today, the lion's share of this type of activity is carried out using modern technology. Moreover, new developments, research and impressive financial support from private / public sources ensure its rapid development. And this, in turn, constantly stimulates an increase in the pace of human anthropogenic influence.
Plains are especially affected by changes. This area has always been a priority for settlement, construction of houses and infrastructure. Moreover, the practice of building embankments and artificial leveling of the terrain has become completely commonplace.
The environment is also changing for the purpose of mining. With the help of technology, people are digging huge quarries, drilling mines, and making embankments in the places of waste rock dumps.
Often scale of activityhuman are comparable with the influence of natural processes. For example, modern technological advances give us the ability to create huge channels. Moreover, in a much shorter time, when compared with the similar formation of river valleys by the flow of water.
The processes of destruction of the relief, called erosion, are greatly aggravated by human activity. First of all, the soil is negatively affected. This is facilitated by the plowing of slopes, the wholesale deforestation, immoderate grazing of cattle, and the laying of road surfaces. Erosion is further exacerbated by the increasing pace of construction (especially for the construction of residential buildings, which require additional work, such as grounding, which measures the resistance of the earth).
The last century has been marked by the erosion of about a third of the world's cultivated land. These processes took place on the largest scale in the large agricultural areas of Russia, the USA, China and India. Fortunately, the problem of land erosion is being actively addressed at the international level. However, the main contribution to reducing the destructive impact on the soil and recreating previously destroyed areas will be made by scientific research, new technologies and competent methods of their application by humans.
