Physical Geology and Geological History of South America

By Edward Revollo

This work intent to give an introduction to the basic principles and
concepts of geology for all those are interested in the understanding
and learn about all the processes and phenomena that formed and
shaped the Earth, since its formation, around 4,800 million years
before present (BP). Early geologists, makes its task of studying and
interpreting these processes, contributed to display the history of the
planet and the origin of the life. Their work were the basis for future
generations of scientists deepened and made new discoveries that
contributed in the understanding of our planet and give a new view
about its formation. Thanks to all these discoveries, geologists were
able to put all the pieces together and understand all the processes
that contributed to the formation of the South American continent
that began in the first moments of the formation of the Earths crust
3,800 million years BP. This book, compile the geological history of
the continent into a single text, while pointing out new aspects that
were not covered at first.

• Language: English
• Publisher: Xlibris US
• Release date: Jan 23, 2015
• ISBN: 9781499032536

Edward Revollo

Edward Revollo, estudió ingeniería geológica en la Universidad Mayor de San Andrés (UMSA), La Paz – Bolivia. Formó parte de los estudios paleo climáticos en la cuenca del Lago Titicaca, que fueron conducidos por las universidades de Duke, Syracuse, Nebraska y UMSA. En el campo laboral, se inició en la exploración de agua subterránea con la autoridad del Lago Titicaca, en la región de Charaña (Bolivia) en 1998, seguidamente trabajó en la exploración petrolera para “BG” en Bolivia en el año 2000. Posteriormente paso a consultoría medio ambiental y de geotecnia para “PRODEM”, “Warrant”, la prefectura y la municipalidad de la ciudad de La Paz, del 2000 al 2004. En el 2005 se relocalizó en los Estados Unidos, donde regresó a la exploración petrolera del 2006 al 2007. En el 2007, colaboró en el proyecto de “Yucca Mountain” en la zona de pruebas de Nevada. Durante el 2008 trabajó en exploración minera para la “Royal Estándar Minerals”. Del 2009 al 2011 trabajó en la Universidad de Lincoln en investigaciones para el ejército de los Estados Unidos relacionadas al efecto del “RPS” para la detección de minas terrestres en diferentes tipos de suelos. Actualmente trabaja en exploración petrolera para “ALS Global”.

Book preview

Prologue

This work intent to give an introduction to the basic principles and concepts of geology for all those are interested in the understanding and learn about all the processes and phenomena that formed and shaped the Earth, since its formation, around 4,800 million years before present (BP). Early geologists, makes its task of studying and interpreting these processes, contributed to display the history of the planet and the origin of the life. Their work were the basis for future generations of scientists deepened and made new discoveries that contributed in the understanding of our planet and give a new view about its formation. Thanks to all these discoveries, geologists were able to put all the pieces together and understand all the processes that contributed to the formation of the South American continent that began in the first moments of the formation of the Earth’s crust 3,800 million years BP. This book, compile the geological history of the continent into a single text, while pointing out new aspects that were not covered at first.

Chapter I: The Earth in the Universe

The history of the Earth is not as simple as we had imagined, since the beginning of time, the mankind wondered, the origin of everything around and only until recent centuries has begun to understand certain things about our world. The Earth is much older than we could imagine. In the beginning was hostile and uninhabitable, but over time there was a series of physical and chemical changes that allowed the origin of the oceans, where life began. There are several theories regarding the origin of life, yet man does not have a satisfactory answer. Life evolved over time and was adapted to different climate change on the planet, occasionally these drastic changes were almost brought to life on the brink of extinction, but despite all these obstacles life go on.

The place of our world in the universe can only be determined by ourselves and the destiny we choose for it. Our world could be prosperous and full of life or sad and dead. We must also take into account the natural resources that exist on Earth are limited, which took hundreds of millions of years to form and once their finish the humanity is going to enter in a crossroad in which an intelligent decision needs to be made. Also our planet has a delicate balance, which by the action of man was broken on many occasions and can hardly be restored in a few decades; all changes in the Earth took centuries to occur.

The Universe

The universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos. Scientific observation of earlier stages in the development of the universe, which can be seen at great distances, suggests that the universe has been governed by the same physical laws and constants throughout most of its extent and history

The Galaxies

The galaxy name is given to each of the huge sets of hundreds or thousands of millions of stars, all gravitationally interacting, and orbiting around a common center. All the stars visible to the naked eye from the ground belong to the Milky Way galaxy, the sun is only a star of this galaxy. In addition to stars and planets, galaxies contain atomic hydrogen, molecular hydrogen, nitrogen, carbon and silicon and other elements in addition to cosmic rays.

A Persian astronomer Al-Sufi, has been recognized as the first to describe the weak fragment of light in the constellation Andromeda, which we now know that is a companion galaxy to our own. In 1780, the French astronomer Charles Messier published a list of objects that included 32 non-stellar objects are actually galaxies. These galaxies are now identified by their Messier (M), the Andromeda galaxy, for example, is known to astronomers as M31.

In the first part of the nineteenth century, thousands of galaxies were identified and cataloged by William, Caroline and John Herschel. Since 1900, photographic explorations have discovered many galaxies. Galaxies at enormous distances from Earth are so tiny on a photograph that is very difficult to distinguish from the stars. The largest known galaxy has about thirteen times more stars than the Milky Way.

In 1912 the American astronomer Vesto M. Slipher, working at the Lowell Observatory in Arizona (USA) found that the spectral lines of all galaxies were shifted toward the red spectral region. His compatriot Edwin Hubble took this as evidence that all galaxies are receding from each other and concluded that the universe was expanding. It is not known whether it will continue expanding or if it contains enough matter to halt the expansion of the galaxies, so they finally come together again

image002.jpg

The Andromeda galaxy is a spiral galaxy similar to ours, although somewhat higher. It is the farthest object visible to the naked eye. It can be seen north of the constellation Andromeda. The Milky Way and Andromeda are the most important members of the Local Group of galaxies, which in turn is outside of the Virgo Cluster, which includes thousands of galaxies.

The Stars

People in ancient times believed that stars were tiny lights on the inside of a large hollow globe. They created stories about them and gave names to the pictures that were captured in the sky night after night, year after year. Only with the birth of modern science of astronomy the true nature of the universe begins to unfold. Scientists cannot say yet exactly what a star is, however, many known facts about these companions of our Sun, which illuminates and warms the Earth. The Sun is the star we know best, is the center of our solar system and all the planets moves around it. The Sun is just an average star among the billions of stars in the Milky Way. Astronomers generally agree that most stars have approximately the same diameter of our Sun, some stars can be only one tenth of its size, and others can be 100 times bigger, like the red giants.

The stars are really incandescent great globes of gas whose brightness depends on its size and temperature. These are massive shining spheres of atomic power, and are currently believed that this energy is released by a process similar to the nuclear reaction that takes place in a hydrogen bomb. The chemical content of a star is determined through the science known as astrophysics. In many stars the gases can be incredibly light, with the particles or atoms of matter in the gas far enough apart as to make it thousands of times less dense than the air we breathe. Even for its lightness, the matter is there perhaps a million times that we have on Earth. They are hydrogen (H), oxygen (O) and nitrogen (N), and perhaps iron (Fe) and calcium (Ca) and other elements. In cooler stars the art can be almost liquid, more like the boiling iron in a blast furnace. In some old stars and comparatively cold, matter can condense so thick that one cubic inch of it would weigh a ton, such stars are called dead or Black Hole. Astrophysicists determine these facts with spectroscopes, by the light of these instruments is possible to determine the type of light that radiates a star, what kind of matter it contains and what is its temperature.

The Black Hole are discovered because they are near bright stars and gravitation force keeps spinning around each other. The movement of the bright star can be determined by the nature of the black hole, in some double stars or binary, a black hole regularly rotates in front of the bright star and cuts the light, this effect is called eclipsing variable star. Some black hole emit infrared radiation that can be photographed. The astronomers measure the distances to stars in light years (one light year is equal to 186,420 miles per second). The nearest visible star is Alpha Centauri, is visible in the Southern hemisphere and is 4.33 light years from our Sun. In the same constellation is a smaller star and perhaps closest, Proximal Centauri, but can only be seen with the help of the telescope.

image004.jpg

The picture shows our sun, which is a yellow dwarf star, the surface temperature is around 5800° K. Is the source of life of our world.

The Solar System

As the Sun moves through space at a speed of 149 miles per second, carries with it many smaller bodies. The Sun and its smaller companions, eight planets, satellites, asteroids, comets, meteorites and interplanetary dust and gas, together form the solar system. These bodies make a revolution in 225 million years around the Milky Way.

Astronomers do not know exactly how far it extends the solar system, the farthest point from the Sun (aphelion) is about 4,474 million miles and the farthest known body from the Sun is Pluto. However, many comets have orbits that take them even further, up to several hundred times the distance of Pluto. The distances are so large that astronomers often use the light year as the unit of distance or 5,880,000,000,000 miles. The Milky Way is about 100,000 light years across.

The nearest neighbor of the solar system is the triple star system Alpha, Proxima and Centauri, which are located about 4.3 light years from our Sun. Evidence suggests that there are at least two planets orbiting a pulsar outside of the solar system, it is estimated that these planets are 1,300 light years from Earth in the direction of the constellation Virgo.

image007.jpg

Distribution of our solar system that shows the inner planets are composed of rocky material and halogens planets which are gas giants.

Asteroids

Through a telescope is possible to see sometimes a point of light that looks like a star but is moving on the background of stars. That or it may be a planet or an asteroid may be a minor planet. Thousands of these small bodies orbiting the Sun most of them have orbits that are located between Mars and Jupiter, originally thought they might be debris from the explosion of a planet, are now generally accepted that matter could never consolidate due to the gravitational effect of Jupiter. These bodies have a diameter ranging from 125 to 625 miles, due to their unstable orbits tend to be thrown into the inner solar system where impact with the Earth and other planets, these impacts generally occur over a period of 50,000 years, the last great impact recorded, occurred around 65 million years, which coincides with the mass extinction of dinosaurs. Other asteroid belt is located closer to the Sun are called Apollo asteroids. The smallest known asteroid passes even within the orbit of Mercury.

Meteorites

A blazing beam of light passes through the night sky and then disappears. On rare occasions the bright lightning crashes to Earth, producing a boom like the thunder of guns and causing a huge explosion on landing. When the ancients watched such shows, they thought they saw stars falling from the heaven, so called for that purpose shooting star or falling star. Today these glowing light trails are more fully known as meteorites and there are small pieces of stone or metal from outer space, they enter the Earth’s atmosphere and vaporizes. Before meeting with the Earth’s atmosphere, these bits of matter are called meteoroids, after entering the atmosphere are called meteors, most meteors never reach the Earth because they are so tiny that vaporize completely shortly after entering the atmosphere sometimes, however the particles are large enough to be partly intact. The large, dense objects that survive the fall to Earth are called meteorites, although thousands of meteoroids entering the atmosphere each year, it is estimated that only an average of 500 actually reaches the earth’s surface before vaporizing.

Comets

A comet has a nucleus of ice and rock, surrounded by a cloudy atmosphere called hair or coma. The American astronomer Fred Whipple in 1949 described the nucleus, which contains almost all the mass of the comet, as a dirty snowball consisting of a mixture of ice and dust. Most of the gases are ejected to form the hair are fragmentary molecules or radicals of the most common elements in the space: hydrogen, carbon, nitrogen and oxygen. The head of a comet, including fuzzy hair, can be larger than the planet Jupiter however the most solid part of comets has a volume of several cubic kilometers only. For example, the nucleus obscured by dust from Halley’s Comet has a size of approximately 38 miles in diameter, which is one of the long-period comets. Comets originate from the so-called Oort cloud, which lies to 100,000 AU (Astronomic Units) from the solar system; this cloud has the largest concentration of comets, which are fired into the system when a disturbance occurs in astronomy, which may be due to passage of a star or other phenomenon.

image010.jpg

Asteroids and comets that inhabit our solar system are countless clubs and every month, astronomers discovered 50 of these bodies.

The Origin of the Solar System

Several theories have been proposed to describe the origin of the solar system, since this happened long ago and the distances involved are huge by Earthly standards, it is extremely difficult to acquire sufficient evidence to test theories of the origin of the solar system. The information from space probes is the most important source of evidence.

The Nebular Theory

This theory was raised by a German philosopher Immanuel Kant, and was subsequently published in 1796 by the mathematician Laplace. This theory explains that all the matter composing the solar system was distributed in a large cloud of gas around the Sun, then this matter and gradually began to turn was condensed, which increase the severity and speed were gradually forming spheres that gave rise to the planets and satellites. This theory pose three centuries ago, this subject is lacking proper scientific basis.

The Planetesimal theory

This theory was put forward by Thomas C. Chamberlin, which postulates that based on a series of observations of solar activity on notice that the sun’s surface arise a series of solar eruptions that throw material into space. Taking this into account is proposed that at some time step a star near the Sun and due to its gravitational pull, there were a series of violent eruptions on the Sun, gradually expelling material forming the different planets and moons in the system. This theory has a serious lack of information, recently has shown that this phenomenon actually occurred, was in a very short time, so that the solar system would have only about two billion years of existence.

Recent theories

There is no satisfactory theory has been postulated for the origin of the solar system a group of German scientists set out to do a review in the Nebular theory, giving a series of adjustments which give a pattern quite reasonable even for the birth of stars. This setting explains the large amount of cosmic dust surrounding the sun escaped into outer space with lots of hydrogen and helium. The remaining quantities of these elements were gradually condensed and forming the various components of the solar system. Due to the presence of cosmic dust that formed even smaller objects to be very close to other larger bodies were broken and formed the asteroid belt between Mars and Jupiter.

image014.jpg

The image shows the formation of the solar system; from the cloud of dust and debris a series of proto planets started to form, gradually with millions of years only nine planets conform our solar system.

Origen of the Earth and the Moon

The disk of gas and dust around the sun was gradually cooling down and the dust particles were clumping together and forming larger bodies until a series of proto planets get formed. Initially the solar system had a large number of these bodies which rotated around the Sun in different directions, frequently these proto planets crossed orbits and impact one with another, due to this solar system had a very chaotic period. Gradually as these impacts were produced some proto planets increasing in size and becoming the dominant inner planets of the solar system as the four rocky planets: Mercury, Venus, Earth and Mars. In this period the Earth didn’t had the Moon, so the stability of the planet was chaotic with no seasons and one day was about 6 hours. Around 4,500 million years there was a great impact with a proto planet called Thea which ripped much of the crust mass of the Earth into space, along with Thea material, the rest of the proto planet got fussed with the Earth’s core. The vast amount of material that was generated in the wake of the impact back to Earth and rest settle for form the Moon. This impact gave greater stability to the Earth’s axis and giving rise to the seasons, the Moon was initially closer to the Earth than is today, around 13,800 miles but gradually moved away slowing down the Earth’s rotation, as the Moon get farther the rotation of the planet increase in a hour and gradually be came the current 24 hours. All these events are considered as pre geological as to reach a point where the planet’s crust was cooled and the engine of the tectonic plates began and the volcanic activity start, at this point the Earth’s atmosphere was mainly composed for hydrogen, helium, ammonia and methane, the volcanoes release gases and change that condition over time.

image016.jpg

The image shows the formation of the Moon: Initially Thea impact with the Earth 1.; After the impact a lot of Thea’s and Earth’s material is expel to the space 2.; Gradually the material start to conform a small body, which revolves around the Earth 3.; Finally the conformation of the Moon is complete 4.

References

CARL SAGAN, Cosmos, Random House, New York, USA, 1980

CARL SAGAN, Comet, Random House, New York, USA, 1985

CHAISSON ERIC J., Solar System Modeling, Cosmic Evolution, Tufts University, 2005.

ENCYCLOPEDIA OCEAN, Earth, Ocean Group, Vol 1, Barcelona, Spain, 1986.

SONDA DAWN, Scrutinize the Solar System mysteries, Deutsche Welle September 2007.

Chapter II: The Geological Time

One of the most important aspects to be taken in the history of the Earth is the geologic time. Just 200 years ago, the age of the Earth was calculated according with the Holy Bible, which begins on October 29 of the year 4004 B.C., giving an age of 6,000 years to the planet. During the late eighteenth century, in 1795 the Scottish geologist James Hutton (considered the father of modern geology) presented a revolutionary theory related with the age of the Planet Earth, this theory was the result of careful observation of the rock characteristics for 50 years, collecting all the information to conclude that the Earth could not be only a few thousand years old, was more likely had billions of years. This opened the door for other scientists such as Charles Darwin, Alfred Wegener and many others after them, who began to investigate our planet for the next several years and found that the World have an amazing age of 4,600 million years.

This conclusion is also accompanied by all the changes that our world had to face throughout its history, which is full of catastrophes, destructions and recreations of different worlds one after another. These phenomena were recorded as a book in different layers of rocks around the entire Earth lagging as data file that is open for those who can interpret it. Based on these parameters the scholars constructed a geological time scale, which allows us to divide the history of the earth in different eons, eras, systems, etc.; in order to properly manage the geological time.

image020.jpg

James Hutton (1726 - 1797), Scottish geologist. He published several works were he postulated the theory that Earth was older than previously thought.

Time and Rock Units

Time units and rock refer to a set of layers (strata), were been deposited in a certain period of time. The elements that make up these strata have their origin in elevated areas; this material was gradually eroded and transported to accumulation zones (basins), on the continent and in the ocean. This process took several million years, during this period there were a number of distinctive features in the depositional environment and in the development of life. These elements gradually froze in time up to this day and interpret its history. In order to explain adequately the rock time factor, the geologists developed a series of tables, which are a guide to get an overview of the relationship between time and rock. The best way to explain this is with the order of geological time, which was separated into five eras, which are Archean (Beginning of the Life), Proterozoic (Developing Life), Paleozoic (Ancient Life), Mesozoic (Middle Life) and Cenozoic (Recent Life), each of these eras is divided into systems, such as seen in the following way:

Archeozoic and Proterozoic

The Archeozoic and Proterozoic eras are the first ones in the geological time scale, which range from 3,800 million years before present (BP) to 500 million years (BP).

Archeozoic Era is divided into four systems comprising of 3800-2500 millions of years BP Proterozoic and is composed of three systems ranging from 2500 to 500 million years BP.

Paleozoic

The Paleozoic era is the third geological period, which is characterized by an explosion of the life from 500 million years BP. This era is also characterized by a series of geological events of great importance for the evolution of life.

The Paleozoic Era is divided into six systems. This was ranging from 500 to 250 million years BP.

Mesozoic and Cenozoic

The Mesozoic and Cenozoic eras are the latest of the geological period. The Mesozoic era is characterized by the appearance of large reptiles (dinosaurs), which were the dominant species on the planet for 180 million years BP, to their extinction in the Late Cretaceous. The Cenozoic Era is the age of mammals which are the dominant species and gradually the man appeared only about 500 thousand years BP.

The Mesozoic Era is divided into three systems, which ranges from 250 to 70 million years BP. The Cenozoic Era is composed of three systems ranging from 70 million years BP to the present.

With the development of this timeline was possible to relate time and rocks, each of the studied rock units in different corners of the world were divided into rock formations, this for a better management of their position in time. Each of these formations possesses lithological, mineralogical and biological characteristics, which enable us to place them in a specific series, system and era.

Development of the time scale

From the first steps taken by James Hutton in 1795 a number of scientists began to conduct exploration and research in different rock groups throughout the world. In 1759 the Italian geologist Giovanni Arduino, establish a classification for the igneous, metamorphic and sedimentary rocks, this classification was used to describe rocks by scientists in the early decades of the nineteenth century, these investigations were accompanied by fossil studies conducted by William Smith in 1815, which set in general framework for the description of the lithological, mineralogical and biological characterized of the rocks.

image025.jpg

Giovanni Arduino (1714 - 1795), performed the rock classification currently used. He is considered the father of geology in Italy.

image027.jpg

William Smith (1769 - 1839), performed the classification of fossils and is considered the father of Paleontology.

In 1822 in England and France in the limestone quarries were called with the Latin term of Cretaceous, in the same year was introduced the Carboniferous term to describe rock mantles in England (Wales) and in continental Europe. In the 1830s, Scottish geologist Roderick Murchison and colleagues conducted a series of descriptions of rock units in England, which started from a particular horizon called Old Red Sandstone. Sometime later a description of sedimentary and metamorphic rocks which been call Silurian, for the Silures an ancient Celtic tribe. Later on was determined the presence of an older sequence which was called Cambrian (Roman name for Wales). Between the Cambrian and the Silurian sequence was observed a series of rocks which was named Ordovician. In the town of Devonshire was located a series of rocks younger than the Silurian which was named as Devonian. In Russia in the province of Perm (Molotov today), Murchison discovered a sequence was overlaying the Devonian rocks, which he call the Permian.

In 1834 in France French and German geologists conducted the description of a sequence of rocks that were over the Permian sequence, these rocks were named Triassic, the same year in the Jura Mountains between France and Switzerland was located a sequence of rocks between the Triassic and Cretaceous, which were nominated as Jurassic. The work of all these geologists during the 1830s was fundamental for the starts of the geologic time scale with the introduction of the terms are currently the series of different geological systems.

The modern timeline

This scale was developed from the work of many geologists, who contributed with their knowledge and work to build the geochronology of the Earth, this table is accompanied by geological events, lifestyle and age prevalent in millions of years. A key aspect to consider in this table is to be updated and improved every certain period of time, which is used for new generations of geologists and other scientists to disclose the results of their research.

Geological Time Measurement

As science progressed developed new methods to determine the age of rocks with greater predictability, for this purpose based on the decomposition of uranium could develop a way to measure time, this method proved to be helpful in determining the age of the rocks, especially for the volcanic material and large igneous bodies. Prior to the discovery of this method the scientists in the mid-nineteenth century, use the velocity of the sedimentation to determine how long it took to form a sedimentary sequence. The average speed of the accumulation of sediments in the ocean is 2.5x10-4 inches per year, taking a sequence of 1312 feet thick have an accumulation of 63 million years. This timing system can be very convenient, as long as the sedimentation rate is constant and there are no changes in the direction of contribution or other geological phenomena or change sedimentary depositional conditions. The radioactive system was discovered through the work of Marie and Pierre Curie in 1896, thanks to this discovery, geology has a more reliable method to measure the time in the rocks. With the radiometric system is possible to determine the age of a rock relatively accurately, based on the decay of uranium 238, which is 7.6 billion atoms per year, this loss continues gradually until it becomes uranium lead. As an example if we have a sample with 5% of Uranium can make the following mathematical relationship.

(Lead / Uranium) x 7.6 billion = time in years

So we have (5/100) x 7.6 billion = 380 million years

In recent years other radiometric systems were found to determine the age of rocks, as the case of Potassium/Argon (K/Ar), Rubidium/Strontium (Rb/St), etc. All these elements have enabled an accurate way to determine the age of rocks accurately, so was able to obtain ages of rocks in different parts of the world, in our case for South America was able to establish ages of rocks in almost all the continent that has helped the development of a relatively accurate timing for existing rocks. But it is necessary to clarify that the dates made in metamorphic rocks tend to be discussed, this is because the ages obtained are clearly of the metamorphism and not the age at which the rock was formed. During the metamorphism the chemical and physical properties of the rock change and there is a total difference from the original rock. For this reason we can say that the age obtained in a metamorphic rock does not reflect the true age and therefore be inferred that the rock is older than the resulting age. As an example we mention the Proterozoic Complex of Lomas Maneches in Bolivia, these rocks are attributed an age of 3,000 million years BP, but as already mentioned this age is the age of metamorphism, therefore these rocks are much older.

image031.jpg

The Map shows the oldest rocks in the South American continent, dated radio system metrics using the Potassium - Argon (K/Ar) system. (Map elaborated by the author)

References

CARL SAGAN, Cosmos, Random House, New York, USA, 1980

STRAHLER ARTHUR N., Physical Geology, Omega, Spain, 1997

Chapter III: Rocks and Geological Structures Classification

The rocks and structures are the most important element of the geological interpretation, these elements allow us to have a better understanding of the conditions under which the rocks were formed and the processes that shaped the surface of our planet. This chapter has the objective to give an overview of where the processes that formed the rocks and generate the structures are originated. The Earth is constituted by four elements: The Core is the heart of the planet and is divided in two parts; the Inner Core is solid and composed for iron (Fe), and is surrounded for the outer core consisting of liquid iron (Fe) and nickel (Ni), has a radius about 137 miles, the temperature can exceed 12,092°F. The outer core has a crater movement that generates a magnetic field, is the natural defense of the Earth from the cosmic radiation; The Mantel, is the layer of Earth that lies between the Crust and the Core, is about 87% of the volume of the planet, with 2,000 miles thick, from the outer core to the Crust. It is divided into two parts, inner mantle, solid, elastic, and outer mantle, fluid, viscous, and the Crust is the outer rocky layer of the Earth. It is comparatively thin, with a thickness ranging from 4 up to 60 Milles, in the mountainous areas of the continents. The most abundant elements of this layer are silicon, oxygen, aluminum and magnesium. Its temperature is directly proportional to the depth observed from the surface and gradually increasing on average 34°F for every 108 feet of depth. The Earth’s Crust were generated the magmatic tectonic processes that shaped the planet’s surface.

image035.jpg

The figure shows the composition of the Terrestrial Globe, which is composed of Crust, Mantle, Outer Core and Inner Core.

To explain the origin of rocks, we must focus on the Mantle of the Earth, which is the original home of the rocks, due to pressure and temperature conditions, it is here in were generates the magma chambers, which are molten rock packages and for their different density gradually rise up to the limit of the Crust. It is at this point where magma chambers are gradually exerting pressure on the crust rocks and generated a series of fractures, which are exploited by molten rock reaching shallower depths and can manifest as volcanic eruptions or igneous bodies.

image038.jpg

The image shows the different outcomes for the rising magma chambers through the sedimentary rocks of the Earth’s crust. The magmatic material can be expressed in the form of volcanic eruptions or igneous bodies trapped below the surface.

Volcanoes

The volcanoes are geological structure through which emerges the lava (molten rock) and gases from inside the magma chambers are below the surface. The rise usually occurs in episodes of violent activity called eruptions, which may vary in intensity, duration and frequency, being from lava flows to extremely destructive explosions. The volcanoes generally adopt a conical shape is formed by the underground magma pressure as well the