Analysis Of Our Planet Earth
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The planet earth is one of the nine planets in the solar system and the only known planet to harbor life and the home of human beings. From the words of Neil Armstrong, one of the astronauts of the famous Apollo 11, "the earth from space resembles a big blue marble with swirling white clouds floating above blue oceans." About 71 percent of the earth's surface is covered with water and the rest is land, mostly in the form of continents that rise above the oceans.
Origin of the Earth
The earth has a unique characteristic that is suited to supporting life. It is neither too hot like planet Mercury, the closest planet to the Sun, nor too cold like planet Mars.
For thousands of years, human being could only wonder about the earth and other observable planets in the solar system. Many ideas such as the earth was a sphere and that it travelled around the Sun were based on brilliant reasoning. It was on the development of scientific method especially in the 18th and 19th centuries, that human beings began to gather data that could be used to verify theories about the earth and the rest of the solar system.
In the second half of the 20th century, more advances in the study of the earth and the solar system occurred because of the development of rockets that could send spacecrafts beyond Earth. Human beings were able to study and observe Earth from space and satellites equipped with scientific instruments. Scientists have studied the solar system and tried to explain how it was formed. Billions of people are wondering how the huge, lively planet came to be. There are many different theories trying to give explanation of how our home planet came to be. One of the most popular theories of the planet's origin is that of God's creation. Many religious group as well as scientists, embrace the belief that God created the universe and the different steps motivating material and natural development and that these steps then resulted in the formation of the galaxies, the solar system and existence of the earth. This theory is known as Theistic evolution or as evolutionary creationism. This theory holds the belief that God exceeds common time and space, with nature having no survival self-sufficient of God's will.
The Theistic Evolution Theory poses many questions that can never be answered directly. The sources available are books written by humans.
Most accepted belief is the theory of creation in the book of Genesis in the Old Testament. This popular theory states that God created the universe in six days .The Bible offers no evidence to prove the story; rather it relies on the faith of the believers to accept it as truth.
Another popular belief is the Big Bang Theory. This theory supports the idea that the universe came about due to a colossal explosion. According to the theory, "the universe goes through a tremendously high - speed rise that expands within a fraction of a second. Then, the excessive heat of electrons and other particles mix. As atoms and particles charge, still extremely hot, they prevent light from shining, creating a sweltering hot fog. Eventually, the electrons merge with additional particles to structure atoms of hydrogen and helium, causing light to at last shine. Giant clouds are soon formed by the hydrogen and helium gases. Weighty elements that are not clustered together are thrown into space to form stars and planets.
Another theory is developed by Immanuel Kant and given scientific form by Pierre Simon Laplace at the end of 18th century. It is known as the Nebular Theory. It was assumed that the solar system in its first state was a nebula, a hot, slowly rotating mass of rare matter, which gradually cooled and contracted, the rotation becoming more rapid, in turn giving nebula a flattened disk-like shape .In time, rings of gaseous matter became separated from the outer part of the disk, until the diminished nebula at the center was surrounded by a series of rings. Out of the material of each ring a great ball was formed, which by shrinking eventually became a planet. The mass at the center of the system condensed to form the sun.
Encounter or collision theories, in which a star passes a close by or actually collides with the sun, try to explain the distribution of angular momentum. According to the Planetisimal theory, developed by Thomas Chamberlin and Forest Ray Moulton, in the early part of 20th century, a star passed close to the sun. Huge tides were raised on the surface; and some of these erupted matters were torn free, and by a cross pull from the star, were thrust bodies called planetesimals. As their orbits crossed, the larger bodies grew by absorbing the planetisimals, thus becoming planets.
The Gaseous Tidal Theory, proposed by James Jeans and Harold Jeffreys in 1918, is a variation of the planetesimal concept. It suggests that a huge tidal wave, raised on the sun by a force of gravity of a passing star, was drawn into a long filament and became detached from the principal mass. As the stream of gaseous material condensed, it separated into masses of various sizes, which by further condensation took the form of a planet. The Dynamic Encounter Theory of Georges Buffon states that the world was formed out of molten materials from the sun that collided with other planets.
According to the Solar Disruption Theory by Georges-Louis Leclerc, the sun and a big star almost collided in space, which made some parts of the sun burst. The pieces formed became planets.
Composition and Structure of the Earth
Geologists divided the earth into three main zones: hydrosphere, lithosphere, and atmosphere.
Hydrosphere consists of the bodies of water that covers 71 percent of the earth's surface. The largest of these are the oceans, which contain over 97 percent of all water on Earth. Glaciers and polar ice caps contain over 2 percent of earths' water in the form of solid ice. Only about 0.6 is under the surface as groundwater. Groundwater is 36 times more plentiful than water found in lakes, inland seas rivers, and in the atmosphere as water vapor. Most of the water in glacier, lakes inland seas, rivers and groundwater is fresh and can be used for drinking and in agriculture.
The atmosphere is the great blanket of gases that surrounds the earth. It is arranged in five layers: troposphere, stratosphere, mesosphere, and exosphere.
Lithosphere refers to all of the earth, from its surface to its center. The earth contains three regions - crust, mantle, and core. Crust is the outermost layer of the earth. The crust consists of the continents, and other land areas and the basins or floor of the oceans. It has an average thickness of 25 mile.
Mantle is about 800 miles thick of solid silicate rock. Core contains iron and nickel whose outer core is liquid and the inner core is solid.
Changes on the Earth's Surface
Think and Respond
How forces inside the earth create and change landforms? Earth's surface has been constantly changing ever since the planet was formed. Most of these changes have been taking place slowly over millions of years. These gradual changes resulted in modifications including the formation, erosion, re-formation of mountain ranges, the movement of continents, the creation of super continents and the break-up of smaller continents.
There are factors responsible for the changes in the earth's surface. These are:
Weathering. Weathering is the breakdown of rock at and near the surface of the Earth. Most rocks originally formed in a hot, high pressure environment below the surface where there was little water. Once the rock reached earth's surface they were subjected to temperature changes and expand to water. When rocks are subjected to these kinds of conditions, the minerals they contain tend to change. These changes constitute the process of weathering. There are two types of weathering; physical weathering and chemical weathering.
Physical weathering includes a decrease in the size of rock materials. Freezing and thawing of water in rock countries for example, splits rocks into small pieces because water expands when it freezes.
Chemical weathering involves a chemical change in the composition of rock. Chemical weathering is important to man because it creates the clay minerals that are important component of soil, which is the basis for agriculture.
Erosion. Erosion is the process that removes loose and weathered rock and carries it to a new site. Water, wind, and glacial ice combined with the force of gravity can cause erosion.
Soil erosion and gullying in the upper Panuco basin, Sierra Madre Oriental, eastern Mexico
Think and Explain
Why is erosion dangerous? Erosion by running water is the most common process of erosion. When water moves downhill, it can carry loose rocks or soil with it. The force of the running water removes loose particles formed by weathering. In the process, gullies and valleys are lengthened, widened, and deepen. The Grand Canyon of the Colorado River is an example of the eroding power of water. Over a million years the Colorado River has cut a canyon that is more than 1 mile deep. The Nile River of Egypt, for example, brings rich soil from the mountains and spreads it along its banks. Because of this, the Nile Valley is one of the most fertile areas in the world. It is the only part of Egypt where crops can grow, a reason why Egypt was known as "The Gift of Nile." On the other hand, the Huang Ho or Yellow River in Northern China often overflows its banks and floods farms and homes. Over the years Huang Ho has done so much damage that people call this river "China's Sorrow."
Erosion can also occur as glacier, or large bodies of ice, move across the surface of the earth. As they move, glaciers change the land destroying forests, carving out valleys, altering the course of the rivers and wearing down mountaintops.
Wind is an important cause of erosion only in arid or dry regions. Wind carries sand and dirt, which can scour even solid rock. Erosion caused by wind can either help or hurt people. The plains of Northern China for example, have a thick, rich type of soil that is carried by winds blowing from the deserts far to the west. This soil allows farmers in Northern China to raise great amount of wheat and other food crops.
Think and Explain
How do you account today's flash floods to soil erosion?
Many factors determine the rate and kind of erosion that occurs in a certain area. Then climate of a given area determines the distribution, amount, and kind of precipitation that the area receives, thus, the type and rate of weathering. An area with an arid climate erodes differently than the area with a humid climate. The elevation of an area also plays an important role by determining the potential energy of running water. The higher the elevation, the more water will flow due to the force of gravity.
Think and Explain
How do scientists predict when and where earthquakes may occur?Opposite the leveling is a force responsible for raising mountains, and plateaus and for creating new landmasses. These changes on earth surface occur in the outermost solid portion of Earth, known as lithosphere. The lithosphere consists of the crust and another region known as the upper mantle. Scientists believe that the lithosphere is broken into a series of plates, or segments. According to the theory of plate tectonics, these plates move around on earth's surface over long periods of time. These plates move in different ways in relation to each other.
They pull apart or move away from each other, they collide or move against each other, or they slide past each other as they move sideways. These shaking movements of the earth called earthquakes explain geological occurrences such as volcanic eruptions, as well as mountain building and the formation of oceans and continents.
Yale Peabody Museum/www.peabody.yale.edu/platetectonics/author
Earth's Physical Features
The natural features of the earth's land surfaces are called landforms. These features are used to describe and help people to locate specific places.
Think and Explain
Why is the earth the only planet for man?Landforms are defined as the natural physical features found on the surface of the earth. Landforms are created as a result of the various forces of nature such as wind, water and ice and also by the movement of the earth's tectonic plates. Due to these actions, the soil gets eroded and deposited somewhere far from the site of erosion, thus leads to the formation of different landforms. Some landforms are created in a matter of few hours; others take millions of years to appear. A group of landforms in a particular area is called its landscape.
Geographers and geologists refer to four major landforms. Large flat mainly grassy areas are the plains. Lands with elevations more than 1,000 feet above the surrounding areas are called mountains. Hills are elevated land masses that are less than 1,000 feet above their surroundings. Plateaus are flat elevated areas perched between 300 to 3,000 feet high. Minor landforms include buttes, canyons, valleys and basins.
Think and Respond
How do forces inside the earth create and change landforms? These major landforms were formed as a result of tectonic activity, or earthquakes. Other landforms are the result of volcanic eruptions. In fact, mountains that were formed by tectonic activity are called fold mountains, while those formed by volcanic eruptions are called volcanic mountains. Still other landforms resulted from the effects of weathering, erosion and the movement of glaciers.
Think and Respond
How did bodies of water such as rivers and seas affect societies? Mountains are perhaps the most noticeable of the major landforms and are found on every continent, as well as beneath the ocean. The highest mountain is Mount Everest in the Himalayas at 29,028 feet. The largest mountain, by volume, is Hawaii's Maono Loa. The longest chain of mountains is the Mid Ocean Range. Both Easter Island in the Pacific Ocean and Iceland are member peaks of this range.
More than half of the earth's surface is covered by plains like the Central Plains of the United States and the plains in Eastern China. Some plains that continue to grow in surface area are the deltas that form by land carried in the current and deposited at the mouths of major rivers. The largest deltas are the Nile River Delta, Mississippi River Delta and Rhone River Delta.
Plateaus account for about 30 percent of the earth's surface. They are elevations that terminate in flat lands. Some people call them tablelands because of their shape. There are often layers of both hard and soft rock in a plateau. These landforms were caused when the earth's crust was forced upward.
Types and Characteristic Features of Landforms
There are many types of landforms on the earth's surface. Each landform is characterized by its slope, elevation, soil and rock type, stratification and orientation. Some of the common types of landforms and their characteristics are the following:
Mountains: Mountains are areas, which are higher than the surrounding areas and are characterized by a peak, e.g. The Himalayas. Surprisingly, they are more frequently present in the oceans than in land. A mountain is steeper than a hill. Mountains are formed due the tectonic movement such as an earthquake or a volcanic eruption. A few are resulted due to erosion of the surrounding areas by the action of wind, water or ice.
Plateaus: Plateaus are large highland flat areas separated from the surrounding areas by a steep slope, e.g. The Tibetan plateau. Plateaus are formed due to various actions such as collision of the earth's tectonic plates, uplift of the earth's crust by the action of magma; some are resulted due to the lava flow from the volcanic eruption.
Islands: Islands are areas that are completely surrounded by water, e.g. The Hawaiian Islands. Islands are formed either as a result of the volcanic eruption or due to the presence of hot spots on the lithosphere.
Plains: Plains are flat areas or low relief areas on the earth's surface, e.g. prairies, steppes. Plains are formed due to the sedimentation of the eroded soil from the hills and mountains or due to the flowing lava deposited by the agents of wind, water and ice.
Valleys: Valleys are flat areas of land between the hills or mountains, e.g. The California Central Valley. Mostly they are formed by the actions of rivers and glaciers. Depending upon the shape, valley forms are classified as U-shaped or V-shaped valley. V-shaped valleys are formed by flowing water or rivers, whereas U-shaped valleys are formed by glaciers.
Deserts: Deserts are very dry lands with little or no rainfall, for example, The Sahara desert. Mostly deserts are formed in rain shadow areas, which are leeward of a mountain range with respect to the wind direction. Thus, the mountains block the passage of wind resulting in little or sometimes no rain.
Loess: Loess are deposits of silt and with a little amount of sand and clay. Many a times wind action is responsible for formation of loess; however sometimes glacial activity can also form loess.
Rivers: Rivers are natural flowing stream of freshwater, e.g. The Nile. They mostly flow towards lakes or oceans but sometimes they dried up without reaching another water body. River water is collected from the surface water runoffs, groundwater water recharge and sometimes from the water reservoirs such as glaciers. Landforms definitely play an important role in the formation of rivers.
Oceans: Oceans are the biggest form of water and are saline, such as The Pacific Ocean. Oceans of the world covers around 71% of the earth's surface and control the weather and climate of the earth's surface.
Think and Explain
Are landforms still affecting today's development?
Glaciers: Glaciers are huge slow moving body of ice. Glaciers are formed due to the compaction of snow layers and moves with respect to gravity and pressure. Mainly there are two types of glaciers- Alpine glaciers, which are formed in high mountains and Continental glaciers, which are formed in cold Polar Regions.
Land surface of the earth was divided into seven landmasses called continents.
Land surface of the earth was divided into seven landmasses called continents. A continent is defined as a large unbroken land mass completely surrounded by water, although in some cases continents are (or were in part) connected by land bridges. The seven continents are North America, South America, Europe, Asia, Africa, Australia, and Antarctica. The islands in the Pacific are often called Oceania.
Illus. 1. The seven continents of the world.
Geographically, Europe, including the British Isles, is a large western peninsula of the continent of Asia; and many geographers, refer to Europe and Asia, as the Eurasian continent. But traditionally, Europe is counted as a separate continent, with the Ural and the Caucasus mountains forming the line of demarcation between Europe and Asia. Europe is a large peninsula with a long irregular coastline with varied mountains, and islands.
The continent of Europe is a relatively small part of the Eurasian landmass, encompassing 3,827,308 square miles. It is bounded on the west by the Atlantic Ocean, on the south by the Mediterranean Sea and the Black Sea, on the east by Asia, and on the north by the Arctic Ocean. Europe's highest point is Mt. Elbrus in Russia, at 18,510 feet above sea level. Its lowest point is the Caspian Sea in Russia, at 90 feet below sea level. The longest river in Europe is the Volga, which runs through Russia for about 2,300 miles. Also in Russia is the continent's largest lake, Lake Ladoga, which covers an area of 6,834 square miles.
Europe consists of over 40 countries, with approximate total population of 803, 850, 858 in 2009. Its two major English-speaking countries, the United Kingdom and Ireland, are island nations. Germany and France are the two most populous nations of central Europe. Two of Europe's southernmost countries, Greece and Italy are Mediterranean Sea peninsulas. Four of the continent's northern countries - Denmark, Finland, Norway, and Sweden - comprise a region known as Scandinavia.
Think and Respond
What physical features might have been a great help for the Europeans to explore and settle in the Philippines? Asia is the largest of the Earth's seven continents, lying almost entirely in the Northern Hemisphere. With outlying islands, it covers an estimated 44,391,000 sq km (17,139,000 sq mi), or about 30 percent of the world's total land area. Its peoples account for three-fifths of the world's population; in 2009 Asia had an estimated 4.10 billion inhabitants.
Most geographers regard Asia as bounded on the north by the Arctic Ocean, on the east by the Bering Strait and the Pacific Ocean, on the south by the Indian Ocean, and on the southwest by the Red Sea and Mediterranean Sea. On the west, the Ural Mountain serves as boundary between Europe and Asia. Some geographers include Europe and Asia together in a larger Eurasian region, noting that western Asian countries, such as Turkey, merge almost imperceptibly into Europe.
The continental mainland stretches from the southern end of the Malay Peninsula to Cape Chelyuskin in Siberia. The lowest and highest points on the Earth's surface are in Asia, namely, the shore of the Dead Sea which is 408 m/1,340 ft. below sea level in 1996) and Mount Everest which is which is about 8,850 m/29,035 ft above sea level.
Asia is divided into different regional groups namely; Southwest Asia, South Asia, East Asia, Southeast Asia and Central or North Asia.
Southwest Asia spans a vast area that encompasses the following countries; Afghanistan, Bahrain, Cyprus, Iran, Iraq, Israel, Jordan, Kuwait, Lebanon, Libya, Saudi Arabia, Syria, Turkey, and United Arab Emirates.
South Asia is a large landmass that extends southward from the continent of Asia into the Indian Ocean it's nearly 1,591,890 square mile or 2,561,351 sq km occupying about 10 percent of the land area of Asia. This region includes the following countries; Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri-Lanka.
East Asia is separated from the rest of the Asian continent by rugged highlands and towering mountain ranges. It comprises the following countries; China, Japan, Mongolia, North Korea, South Korea, and Taiwan.
Southeast Asia covers a land area of about 1.7 million square miles or 4.4 million sq km. It is bordered by the Pacific Ocean to the east and the Bay of Bengal and the Indian Ocean to the west and south. The following countries are included in the region; Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, Philippines, Singapore, Thailand and Vietnam.
Central Asia/ North Asia is a region from the Caspian Sea in the west to Central China in the east, and from Southern Russia in the north to Afghanistan in the south. It has a varied geography. The region includes the following countries: Georgia, Armenia, Azerbaijan, Kazakhstan, Tajikistan, Turkmenistan, and Uzbekistan.
The third-largest continent on Earth is North America. It lies mostly between the Arctic Circle and the Tropic of Cancer. It is almost completely surrounded by bodies of water, including the Pacific Ocean, the Bering Strait, the Arctic Ocean, the Atlantic Ocean, and the Caribbean Sea and Gulf of Mexico. Area: 9,361,791 sq mi (24,247,039 sq km). Population (2008 est.): 528, 720, 588. It is shaped like an inverted triangle .To the southeast are the Appalachian Mountains and to the west are the younger and much taller Cordilleras. These mountains extend the length of the continent and occupy about one-third of the total land area. The Rocky Mountains constitute the eastern Cordillera. The highest point is Mount McKinley. The Mississippi River basin, including its major tributaries, the Missouri and Ohio, occupies more than one-eighth of the continent's total area. Generally temperate climatic conditions prevail.
South America, fourth largest of the Earth's seven continents after Asia, Africa, and North America occupying 17,820,900 sq km (6,880,700 sq mi), or 12 percent of the Earth's land surface. It lies astride the equator and tropic of Capricorn and is joined by the Isthmus of Panama, on the north, to Central and North America. The continent extends 7,400 km (4,600 mi) from the Caribbean on the north to Cape Horn on the south, and its maximum width, between Ponta do Seixas, on Brazil's Atlantic coast, and Punta Pariñas on Peru's Pacific coast, is 5,160 km (3,210 mi). South America has a 2009 estimated population of 394 million, or 6 percent of the world's people. The continent comprises 12 nations. Ten of the countries are Latin: Argentina, Bolivia, Brazil, Chile, Columbia, Ecuador, Paraguay, Peru, Uruguay, and Venezuela. Two of the nations are former dependencies: Guyana, of the United Kingdom, and Suriname, of The Netherlands. South America also includes French Guiana, an overseas department of France. The coastline of South America is relatively regular except in the extreme south and southwest, where it is indented by numerous inlet.
The Andes Mountain, the second highest mountain range in the world is situated, in South America.
The main lowland is the vast Amazon Basin in the equatorial part of the continent; it is drained by the Amazon River, the world's second longest river. The Orinoco River drains a lowland in the north; to the south lies the Paraguay-Parana' basin. The lowest point in South America (40 m/ 131 ft below sea level) is on Peninsula Valdés in eastern Argentina, and the greatest elevation (6,960 m/22,834 ft) is atop Aconcagua in western Argentina, the highest peak in the Western Hemisphere.
Africa is the second largest of the earth's seven continents, covering, with adjacent islands, about 30,300,000 sq km (about 11,699,000 sq mi), or about 20% of the world's total land area. In the mid 2009, some 999 million people, or about 14.72% of the world's population inhabited Africa.
Straddling the equator, Africa stretches about 8000 km (about 4970 mi) from its northernmost point, Cape Blanc (ar-Ras al-Abyad) in Tunisia, to its southernmost tip, Cape Agulhas in South Africa. The maximum width of the continent, measured from the tip of Cape Verde in Senegal, in the West, to Ras Hafun in Somalia, in the East, is about 7560 km (about 4700 mi). The highest point on the continent is the perpetually snowcapped Mt. Kilimanjaro (5895 m/19,340 ft) in Tanzania, and the lowest is Lake Assal (153 m/502 ft below sea level) in Djibouti. Africa has a regular coastline characterized by few indentations. Its total length is only about 30,490 km (about 18,950 mi); the length of its coastline in proportion to its area is less than that of any other continent.
Think and Respond
Why are the people in the desert usually nomads?
The chief islands of Africa include Madagascar, Zanzibar, Pemba, Mauritius, Réunion, the Seychelles, and the Comoro islands in the Indian Ocean; São Tomé, Príncipe, Annobón, and Bioko in the Gulf of Guinea; Saint Helena, Ascension, and the Bijagós islands in the Atlantic; and the Cape Verde, Canary, and Madeira Islands in the North Atlantic.
Africa may be divided into three major regions: the Northern Plateau, the Central and Southern Plateau, and the Eastern Highlands. Low-lying coastal strips, with the exception of the Mediterranean coast and the Guinea coast, are generally narrow and rise sharply to the plateau.
The outstanding feature of the Northern Plateau is the Sahara, the great desert that occupies more than one-quarter of Africa.
At the border of the Northern Plateau are several mountainous regions. To the Northwest lies the Atlas Mountain, a chain of rugged peaks linked by high plateaus, which extend from Morocco into Tunisia. Other prominent uplands are the Futa Jallon, on the Southwest, and the Adamawa Massif and the Cameroon mountain range, on the South. The Lake Chad Basin is situated in the approximate center of the Northern Plateau. The Central and Southern Plateau is considerably higher than the Northern Plateau and includes west central and South Africa. It contains several major depressions, notably the Congo River Basin and the Kalahari Desert. Other feature South of this plateau is the Drakensberg Mountain.
The Eastern Highlands, the highest portion of the continent, lie near the east coast, extending from the Red Sea South to the Zambezi River. South of the Ethiopian Plateau are a number of towering volcanic peaks, including Mt. Kilimanjaro, Mt. Kenya, and Mt. Elgon. West of the Great Rift Valley is the Ruwenzori Range.
The "continent" of Australia/Oceania links together the continental landmass of Australia with the huge number of widely scattered islands across the Pacific Ocean. This continent includes New Guinea, Tasmania, New Zealand, Hawaii, and the countless islands of Melanesia, Micronesia, and Polynesia.
The continent of Australia is such a relatively low and flat place. Although the Great Dividing Range has some interesting areas such as the Blue Mountains area, and there is some nice mountain scenery, the bulk of the continent is simply just not mountainous at all. The highest point on the Australian landmass is Mt. Kosciusko (7310'/2228m), a peak with a road to the top.
The continent of Australia/Oceania holds a respectable amount of serious mountains situated in the "Oceania". In New Zealand and New Guinea are world-class mountain ranges: Puncak Java, which is 5,030 meter, and in New Guinea is the highest summit in this part of the world. There is also the Southern Alps of New Zealand, which is a craggy, snowy range that challenges the best climbers in the world.
Many other islands of Oceania hold mountains that are either higher or more interesting that those of mainland Australia; highlights include the ranges of Tasmania, Tahiti, Fiji, the Solomon Islands, and the massive shield volcanoes of Hawaii.
Antarctica is the fifth largest of Earth's seven continents. Antarctica surrounds the South Pole and is a place of extremes. It is the southernmost, coldest, iciest, driest, windiest, most remote, and most recently discovered continent. Nearly the entire landmass lies within the Antarctic Circles. Air temperatures of the high inland regions fall below -80°C (-110°F) in winter and rise only to -30°C (-20°F) in summer. Massive ice sheets built up from snow over millions of years cover almost all of the continent and float in huge ice shelves on coastal waters. In winter, frozen seawater (sea ice) more than doubles the size of the Antarctic ice cap. Antarctica's vast areas of ice on land and on sea play a major role in Earth's climate and could be strongly affected by global warming. The melting of Antarctic ice could dramatically raise global sea level.
Antarctica means "opposite to the Arctic," Earth's northernmost region. Antarctica is completely encircled` by the Southern Ocean. The entire area south of the Antarctic Convergence is referred to as the Antarctic region.
Changes in the Earth's Surface
Composition and Structure
Provide the correct answers to complete the puzzle.
The belief that the process of evolution was divinely supervised (Theistic Evolution)
A theory stating that the earth was a product of an explosion of a single extremely dense mass of matter (Big Bang)
A formerly held theory that the solar system evolved as a hot, rotating, flattened gaseous nebula. (Nebular Theory)
It is also known as planetisimal theory (Collision Theory)
The force of gravity of a star which passed closed to the sun, caused the several gases to be torn off which in turn as they cooled off gradually and condensed, they came to form planets.
How does earth differ from other planets?
Choose one that does not belong to the group:
a. troposphere b. stratosphere c. mesosphere d. hydrosphere
a. atmosphere b. hydrosphere c. lithosphere d. stratosphere
a. core b. mantle c. crust d. plate
a. erosion b. weathering c. plate tectonics d. Heat
a. Colorado River b. Nile River c. Pasig River d. Yellow River
"Volcanic eruption may cause changes in the physical features of the earth."
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