My understanding of continental drift Essay Example for Free

My understanding of continental drift Essay The present arrangement of the continents with similarities in outline of opposite seaboards and coasts and, much more reliably, geological data show that the Earths continents that are now on the opposite sides of the oceans were once joined together. Today, scientists believe that about 200 million years ago the continents were joined together to form one supercontinent Pangaea. As the plates that the continents sit on moved, the supercontinent broke up and began to move apart. This continental drift is continuing. However, the ideas of continental drift and especially seafloor spreading remained a minority view until 1950s, when seismic techniques made possible surveying of the crust under the oceans. Then, in the 1950s, it was discovered that the oceanic crust is relatively thin, 5 to 7 kilometres in some places, and the ocean floor hides oceanic ridges, thousands of kilometres in length and several kilometres above the ocean floor. The best-studied example is Mid-Atlantic Ridge, approximately halfway between Europe and America, running north-south up the North Atlantic Ocean. Along the centre of this ridge there is an active rift valley. In 1960 Harry Hess, of Princeton University tried to explain the newly discovered structure of the ocean floor and other previously unknown features with the first model of so-called sea-floor spreading, in accordance to which the ocean ridges are formed by upwelling convection currents in the fluid material of the mantle. As these currents bring material up to the surface at the oceanic ridge, where it spreads outward. As new ocean basins are formed, the continents are pushed further apart. To balance the formation of new crust at the ocean ridge, some oceanic crust is dragged back down under the edge of continents. That takes place at the deep trench systems, mainly in the western Pacific as well as at the edge of some other oceans. Not surprisingly, than half of the worlds active volcanoes above sea level encircle the Pacific Ocean to form the circum-Pacific Ring of Fire. According to Hess model, The Atlantic Ocean becomes wider, at a rate of about 2 centimetres per year, the Pacific shrinks as North America slowly drifting westwards, towards Asia. In 200 million years, people in America probably wont need to cross the Pacific to reach what now is Far East. So according to the plate-tectonics theory, Earths surface is broken into about a dozen of rigid shifting slabs or plates, which average about 80 kilometres in thickness. These plates move relative to one another above a hotter, deeper, more mobile zone at average rates of a few inches per year. There are three common types of boundaries between these moving plates: Divergent or spreading. Adjacent plates pull apart, which causes sea-floor spreading, as described above for the Mid-Atlantic Ridge, which separates the North and South American Plates from the Eurasian and African Plates. Convergent. Plates moving in opposite directions meet and one is dragged down (or subducted) beneath the other. Convergent plate boundaries are also called subduction zones and are typified by the Aleutian Trench, where the Pacific Plate is being subducted under the North American Plate. Transform fault. One plate slides horizontally past another, as in the San Andreas fault zone of California, which marks the boundary between the Pacific and North American Plates. The history of Earths plates since Pangaeas break up until present time is relatively well studied. However, the motion of the plates is less clear in pre-Pangaea times. Oceanic crust has an average age of only 55 million years, as the age of continental crust averages about 2. 3 billion years, with the oldest known rocks dating back 3. 96 billion years. Probably our planet has had several supercontinents like Pangaea throughout time. These supercontinents all went through a cycle similar to Pangaeas. Geological data show that more than 600 millions years ago most of the land that now forms South America, Africa, India, Antarctica and Australia was grouped together in one supercontinent located roughly across the equator, called Gondwanaland. Other continents were also assembling together. North America and Greenland had, by that time, been attached to each other for hundreds of millions of years. By about 400 millions years ago, this chunk of continental material collided with what is now part of Europe, and the pieces welded together to form so-called Old Red Sandstone. By then Gondwanaland crossed the South Pole and was moving northward. A little more than 250 million years ago, Gondwanaland and the Old Red Sandstone continent collided and struck together. Then the last remaining independent plate, present-day Asia, collided with the northern part of this supercontinent and was welded on to Europe. Thats how all modern continents were joined together in Pangaea, which was stretching from the South Pole to high northern latitudes. In the foreseeable future, the Atlantic Ocean will be expanding, pushing North America westwards, while the Pacific Ocean will be shrinking. The Mediterranean Sea will eventually disappear, connecting Africa with Europe. India will be continuing to push into the southern Asian subcontinent, pushing the Himalayas even higher. Short description of the web sites: Plate Tectonics, the Cause of Earthquakes including the chapter Earthquakes are caused by plate movement, http://www. seismo. unr. edu/ftp/pub/louie/class/100/plate-tectonics. html. The site explains and illustrates the links between the plates and earthquakes, featuring a few highly informative satellite pictures and drawings. It is shown that the plates consist of an outer layer of the Earth, the lithosphere. Occasionally the hot asthenosphere of the Earth finds a weak place in the lithosphere to rise buoyantly as a plume, or hotspot. Only lithosphere has the strength and the brittle behavior to fracture in an earthquake. The location of earthquakes around the globe is shown. The site demonstrates that the boundaries between the plates grind against each other, producing most earthquakes, thus the lines of earthquakes help define the plates. Earthquake occurrence in different plate tectonic settings is shown with figures and pictures. Plate Tectonics, http://www. ucmp. berkeley. edu/geology/tectonics. html. This site explains the history of human understanding of the Earth and provides a brief overview of the theories behind it. 13 wonderful animations of Plate Tectonics movement in different epochs of Earths history are available on the site in the following formats: *. gif (these load rather slowly) and *. avi, *. mov (for faster Internet connection). Rates of Plate Movement During the Phanerozoic, www. geocities. com/earthhistory/plate2. htm. According to various forms of the Noah`s Flood model, rates of plate motion during the `Phanerozoic` were on the order of several thousand meters per day, and all or most Phanerozoic crustal displacement is considered to have occurred during a brief catastrophe occurring about 2500BCE and lasting only `weeks or months. ` There are a variety of methods which can be used to estimate rates of plate movement for given times in the past. Today, the movement of tectonic plates can be directly measured by a variety of geodetic technologies, including satellite laser ranging (SLR), Very Long Baseline Interferometry (VLBI), and Global Positioning Systems (GPS). Magnetic Island Formation, www. rzg. mpg. de/~sip/thesis/node58. html. Magnetic islands may form upon the flux surfaces for which the field lines are orthogonal to the wave vector of the perturbation since no energy is required to bend the magnetic field lines. The sites show how an expression for the width of these islands is derived. The analytical calculation using this expression is found to be in good agreement with real space data. Island Formation, http://www. hawaii. edu/environment/ainakumuwai/html/ainakumuwaiislandformation. htm. The formation and evolution of Kauai, the oldest of the eight major Hawaiian Islands and a younger member of the Hawaiian-Emperor Volcanic Chain, are thoroughly studied. The Tethyan Himalayas, http://www. geoahead. com/strati/india/index. cfm? page=himalayas_tethyan. The site is devoted to the geology of The Tethyan Himalayas. The belt extending from Kashmir to Nepal can be best studied in two areas – Spiti valley in Himachal Pradesh and Kashmir – where we can see a continuous succession from Precambrian to Mesozoic ages. The Phanerozoic rocks have yielded rich fossils of trilobites, graptolites, brachiopods, cephalopods, gastropods, etc. Facts About Mountains, http://www. woodlands-junior. kent. sch. uk/Homework/mountains. htm. This is the wide illustrated collection of basic facts about mountains, which includes the chapters as various as What are Mountains? , Use of Mountains, How are Mountains formed? , Climate and Mountains, Types of mountains, Nature and Mountains, Tallest Mountains, People, Mountains and Tourism, Mountains around the World, Volcanoes, Mountain Ranges. Quick Facts about Mountains are also included. Moon Has a Small Core Says LP Scientists, http://www. spacedaily. com/news/water-99l. html. The site cites the data from NASAs $63 million Lunar Prospector, which supports mounting evidence that the moon may still retain a small molten core, and was formed in a way unique within our solar system, after a Mars-sized planet smashed into a proto-Earth. It is noted that the new data agrees with Apollo mission seismic and sample-return evidence that suggests the moon is partly made of the same stuff as the Earths upper crust, or mantle. And their findings agree with results released earlier this year by NASA Jet Propulsion Lab scientists who used Lunar Prospector to make a gravity map of the moon and who also conclude that the moon has a small, partially molten core. Works used J. Gribbin. Almost Everyones Guide to Science: The Universe, Life and Everything. Weidenfeld Nicolson. London, 1998. Tilling, Heliker, and Wright. Eruptions of Hawaiian Volcanoes: Past, Present, and Future: Department of the Interior/U. S. Geological Survey Publication, Washington, D. C. , 1987. The web sites described above.

The Ever Changing Concept of Health Essay -- Health & Wellness

With the dominance of medicine over the past two hundred years many historical health concepts have gone through various changes. The definition of health is dependent on one’s perspective, be it lay, professional or from influences of specific cultures or social ideals and health policies of a particular time or place (Fleming & Parker 2012, p.30, Naidoo & Wills 2000). An exploration through history will reflect on the health philosophies of the ancient Greeks and Romans, the Middle Age’s concept of quarantine and isolation and the religious theories of disease including a brief insight into the renaissance. Subsequently, a discussion of health concepts of the past two centuries including 19th century sanitary reform, the dominance in the 20th century of the medical model of health care. This paper will look at the shift away from the medical model and the 21st century concept of health promotion and multidisciplinary care, using allied health professionals. I will argue that attention to the achievements and failures of the historical concepts of health, equips allied health professionals with an opportunity to objectively decide which of these practices have relevance or are useful in developing new approaches for positive health outcomes. In ancient times religion and science were tied in together when it came to health and everyday living. The ruins throughout Greece and Italy stand as testament to their ingenuity with creating and building infrastructure, but also of the people’s belief in the power and influence of the ancient Gods to heal illness (Krieger 2012, p.47, Hays 1998, p.9). According to Tountas (2009) the ancient Greeks were the first to break with mystical notions of health re-orienting ‘medicine toward a ... ...model of illness categories’ in GL, Albrecht, R, Fitzpatrick, SC, Scrimshaw (ed). 2003, The handbook of social studies of health and medicine, pp. 9-23, Sage publications, London, available at http://books.google.com.au Veith, I 1980, ‘Changing concepts of health care: An historian's View’ Western Journal Medicine, vol.133, no.6, pp.532-538 Vlahov, D, Gibble, E, Freudenberg, N & Galea, S 2004, ‘Cities and Health: history, Approaches, Academic medicine, vol.79, no.12 World Health Organization (WHO) 1986, The Ottawa charter for health promotion, Ottawa: Canadian Public Health Association. http://www.who.int/hpr/NPH/docs/ottawa_charter_hp.pdf Yuil, C 2002, ‘Concepts of health and medicine’ in Barry, A and Yuil, C 2008, Understanding the sociology of health: an introduction 2nd ed, pp.22-33, Sage publications Ltd, London, available at http://books.google.com.au

Cold as Ice vs. Hot as Hell Essay

â€Å"Cold as Ice vs. hot as hell† is a metaphor that is applied to our daily lives. At times we are not in its control. The following metaphors described, â€Å"Cold as ice vs. hot as hell† as a characteristic or personality. Allow me to explain the differences between both of the following metaphors meanings. It is with in our nature to remain either calm or peaceful, yet at times we have the most complex mental personalities. This metaphor would be an alteration of â€Å"cold as ice vs. hot as hell of types of personalities and characteristics in them. For example: anger, temper, serenity and tranquility. The outcome of these traits would be a â€Å"cold as ice vs. hot as hell† defining two metaphors in our daily lives struggles. â€Å"Cold as Ice† is a metaphor that is practically in people that remain calm at all times. There are those who experience depression and still remain in a calm state of mind. Imagine your daily routine, and then suddenly something catastrophic occurs, everyone becomes temperamental and violent. These individuals remain calm, focus and open minded to thoughts and opinions. This enables people to think outside of the box and undertake various mental explorations. Being aware there are no limits to our thinking process. The hypothesis result is being successful in life as long you put your mind to it in an environment surrounded of positive people. When you hear or observe positive reinforcement we tend to rationalize, resulting to be more conscious of our surroundings, allowing us to maintain a calm state of mind. â€Å"Optimism is the faith that leads to achievement. Nothing can be done without hope and confidence.† (Helen Keller) A negative characteristic is someone that was raised in a different perspective in life, violence, hate and no love. Being around angry people, full of resentment are negative qualities of a pessimistic person. Is it possible this could be someone who lives by the metaphor, â€Å"hot as hell† always on a short fuse? Could this be a form of adversity to keep them from being happy with him or herself, and other people? For example those people who are going through depression, suicidal thoughts, and many ups and downs in day-to-day activities, which can be difficult. The inability to communicate with others and on a constant hot temper may think that life is not worth living. A constant frustration and pressure will not allow them to be happy. One moment they are happy and another they are on a fuse waiting to explode. Most people that are angry get caught up with an overwhelming of emotions. We are so engaged in anger our reasoning will not work. When anger is responded with an ger it will only make the problem escalate. A wise man said the following â€Å"Pessimist one who, when he has the choice of two evils, chooses both.† (Oscar Wilde) Many individuals are brought up with different perception in life. As infants we demonstrate our personality through love and always wanting attention. Through parental guidance we leave our mothers womb not knowing what is to come of our beliefs and manners. We are also informed that life is to be cherished and to not take life for granted. Honestly we all have same level of â€Å"cold as ice vs. hot as hell†. We all have our moments of struggles to remain calm. Some may come as fighting a profound addiction of serenity. From the day that we are born till the day we pass, everyone will always have to face the struggles and in the process we encounter these metaphors. Lets all maintain peace on earth and tranquility among humanity. World peace is produced to make the world a better place to live in; this phrase must be cherished forever. REFERENCES Keller, H. ( Optimism is the faith: Para 2. Retrieved October 27, 2012 http://bibleversesbytopic.com/quotes/optimism..html Wilde, O. Pessimist Para 3 Retrieved October 27, 2012 http://wisdomquotes.com/quote/oscar-wilde-5.html

Gas Prices in the United States - 1257 Words

Gas Prices in the United States Introduction and Claim No one enjoys paying high prices for gasoline in the United States. In fact when gasoline prices rise to levels above $3 and $4 dollars and even up to $5 a gallon it hurts the economy because it hurts consumers. This paper focuses on gasoline prices and how gasoline prices affect the way Americans drive their cars and trucks. Thesis: Notwithstanding the cynical view that gasoline distributors are manipulating prices to gouge consumers, the literature reflects that prices rise and fall in most cases primarily based on market-driven forces, and on problems with refineries. Moreover, when the government sets higher mileage standards for vehicles, it means cars go a lot farther on a gallon notwithstanding the price of that gallon of gasoline. The Literature on Gasoline Prices Background As a quick review, information provided by the Research and Innovative Technology Administration, a division of the Bureau of Transportation Statistics (which is a division of the U.S. Department of Transportation) is helpful in terms of following the prices of the cost of a gallon of gasoline from January 2002 through January 2012. In January, 2002, the average cost of a gallon of gasoline was just over a dollar; by January 2004 the cost of a gallon of gasoline had risen to $1.75; and by January 2006 the price rose to around $3.00 a gallon. Then in January 2008 the cost of gas was up to $4.00; it dipped to around $2.00 briefly in 2009Show MoreRelatedEssay on Rising Gas Prices in the United States1015 Words   |  5 Pagesthe beauty of nature. Teenagers took joy rides around town to meet friends and rode from one â€Å"hot spot† to another. Those were the days when gas prices were affordable to the average American. 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