The Eruption of Toba

Introduction The largest volcanic explosion in the late Pleistocene occurred in Lake Toba, approximately 72,500 (+- 3000) years ago. The super eruption of Toba has attracted a lot of scientific disrepute due to various reasons. When viewed from space, the caldera is observed as one of the biggest volcanic craters on earth, since it measures over 100km.Advertising We will write a custom research paper sample on The Eruption of Toba specifically for you for only $16.05 $11/page Learn More On the steep was of the caldera is lake Toba. This lake is said to be the largest volcanic lake on earth. Various scientists including Gasparotto, Spadaforab, Summac, Tateoc, Spadafora and Summa (567) and Jones, Gregory and Stott (725) sugest that the eruption resulted in a massive volcanic winter that caused a human population bottleneck. Super-volcanoes are colossal eruptions that are referred to as super-eruptions, and they vary from other catastrophes like tsunamis or earthquakes since their environmental outcomes threaten global civilization (Buhring and Sarnthein 277). These super eruptions are known to occur once in about 500,000 years, like the largest Yellowstone eruption in the USA, or the Toba eruption in Indonesia. Figure 1: Distribution of volcanic ash from the 73 ka Toba super-eruption showing location of marine cores and sections sampled in India According to Ninkovich, Sparks and Ledbetter (5), super-eruptions occur in areas of the earth where the tectonic plates collide. Ambrose, Williams and Chattopadhyaya (167) also suggest that super-eruptions can occur in areas where hot material wells up from the deep earth interior below a continent.Advertising Looking for research paper on geography? Let's see if we can help you! Get your first paper with 15% OFF Learn More According to Williams and Clarke (633), there are many regions on earth that are suspected of volcanic activity, like Andes and Japan. A cause for concern i s the location of super-volcanoes within or near continents, which impies that these vents are situated in areas that have crowded populations (Lang, Leuenberger Schwander 934). This paper looks at the eological setting of Toba, in an effort to understand the super eruption and its probable effects. In doing this, this study seekd to validat that the eruption resulted in the putative bottleneck. Table 1:  Particle size distribution of the YTT ash at the Rehi section, Son valley, India. Geological Setting of Toba Toba is located in western Indonesia, in the island of Sumatra, in the north province. It is found in the Barisan Mountains as shown in figure 1. Fig. 2: Tectonic setting and location map (inset) of the Toba Caldera. Tectonic map modified from Simkin et al. (2006).Advertising We will write a custom research paper sample on The Eruption of Toba specifically for you for only $16.05 $11/page Learn More These mountains comprise metamorphic rock s, Quaternary volcanic and Miocene sedimentary rocks (Ambrose 274). De Silva (671) suggests that Indian-Austrlain plate located beneath the continental Eurasisn subdues a the rate of aproximately 5.5cm.year, towards the Sunda trench, which has resulted in the formation of an active volcanic (Gathorne-Hardy and Harcourt-Smith 228). Sadler and Grattan (186) suggest that the crust is about 30 to 39 km thick under Toba, with a visible depth of around 125 km (De Silva 671). This is an indication of a 30 degrees subduction angle, which has caused the formation of two parallel faults that lie between the trench and vulcanic arc. One of the faults, the vertical Sumatran, marks the border between the Eurasian plate and most of the Volcanic arc and fore arc basin on the north east and south west respectively. The other fault, Mentawai, forms the division between the fore arc basin and the fore arc accretionary sridge complex in the southwest direction (Erwin Vogel 894). According to Westgate , Shane and Pearce there is a dxtral displacement aong the Sumatran Fault. The displacement extends for about 150 km. It is referred to as the Investogator Ridge Fracture Zon (IFZ), with a subduction that is directly nelow Toba. The results of a geometry assessemt of the subduction slab beneath Toba by Chesner et. al. (201) suggest that there is a bend in the slab that coincides with Toba.Advertising Looking for research paper on geography? Let's see if we can help you! Get your first paper with 15% OFF Learn More The study also showed high seismicity along the subducted portion of the IFZ, which suggests the probability of IFZ concentrating volatile release into the mantle wedge beneath Toba (Chesner et. al 201). Figure 3: Bathymetric map of Lake Toba. Depth is represented by isochromes; 100 m contour lines are plotted for reference. The Toba Super eruption The single event of the Toba eruption resulted in a minimum magma eruption of 2,800 km. The magnitude of the eruption was noted as 8.8, which made it one of the largest eruptions in the Quaternary geologic period. The super eruption caused an injection of over 1015 kg of fine ash into stratosphere, while the pyroclastic flows extended for an area of approximately 105 km2 with lava reaching both the Malacca straits and the Indian Ocean. Kelly, Jones and Pengqun (550) suggest that there are layers of tephra in India, at a location that is over 3000 km away from Toba. The ignimbrite extended from one coast to the next, causing a wide area o f the North Sumatra to be drowned. Moreover, there was an aerosol cloud and dust cloud that covered the globe. The possible effects of the cataclysmic eruption include the total obliteration of both flora and fauna in North Sumatra by the ignimbrite, considerable effects on flora and fauna by ash fall in Southeast Asia, as well as, the regional or global change in temperature and effects on the environment. The Toba Catastrophist Theory The Toba catastrophe theory suggests that the super-eruption resulted in the population decline. Scientists suggest that the super-eruption is the worst disaster that human beings have ever been faced. The volcano eruption in Toba resulted in the exhaustion of large amounts of fine ash and aerosols into the atmospheres. The expulsion of these fumes is compared to nuclear-winter situations (Samuel, Harbury, Bakri, Banner Hartono 350), since the global land temperatures fell by 5-15 degrees Celsius, and the surface of the ocean, and other low altitude s, cooled by 2-6 degrees Celsius. This scenario is thought to have prolonged for several years. As a result, the persistence of soot in the atmosphere for 3 years or so may have resulted in a cooling of the climate (Pattan, Shane Banakar 244). This climatic change is though to have extended for several decades, due to the climatic feedbacks such as increased snow cover and sea ice, resulting in less solar radiation reaching the earth’s surface. Consequently, the earth’s temperature remained low since the ground and atmosphere were not heated up. Researchers suggest that the human population faced a bottleneck during this period, due to the rapid decline in the number of females by about 500, in a population that was thought to have only 4000 individuals (Hawks, Hunley, Lee Wolpoff 18). Data suggests that the eruption caused a peak in sulfur aerosol levels in the GISPs ice core, in addition to the global climatic change. According to ice core data, the weather was coo ler for several centuries after the eruption of Toba. Based on the estimates, the Toba eruption resulted in the near extinction of modern humans. Ambrose, Williams and Chattopadhyaya suggest that this led to the human population, though Oppenheimer (1593) provides an alternative hypothesis, arguing that the Toba super-eruption did not have a significant effect on human existence. Oppenheimer (1593) suggests that human beings should not have been the only ones facing termination. According to Rose and Chesner (913), the Toba induced winter should have resulted in an environmental catastrophe resulting in a population crash of more specialised ecological flora and fauna, causing them to be extinct, in a similar manner that it affected human population. In support of this notion, Gates and Ritchie suggest that the Toba super-eruption did not lead to the extinction of any mammal. In adtion to this, studies by Gathorne-Hardy and Harcourt-Smith (228), on the effects of super-eruptions on flora and fauna suggest that they do not result in mass extinctions, which disapproves the Toba catastrophe theory. According to Gasparotto, Spadafora and Summa (569), a bottleneck in human populations would have assumed the shape of an hour glass, causing the human population to crash at 73.5 Ka and then expand again later. According to Schulz, Emeis and Erlenkeuser (22), the studies on human genome that analyse nuclear sequences suggest that the Y chromosome and mitochondrial DNA support the existence of a bottleneck. Consequently, Robock, Ammann and Oman (114) support the possibility of a bottleneck, though they raise concerns about the time when the bottleneck is expected to have occurred. Some research suggests that the phenomena occurred over 2 million years ago (Petraglia, Clarkson and Ditchfield 114), while other researchers provide evidence of a long period of stasis that was followed by a population expansion around 75,000 years ago. The different opinions with regard to t he bottleneck differ on the timing of the event, which raises concerns as to whether it was caused by the super-eruption at Toba. Differences also arise based on the shape of the bottleneck, in terms of an hourglass model or a short bottle with a long neck. The hourglass model suggests a short period of human population decrease, followed by an expansion, while the long neck period indicates a proonged period of winter, and low population density (Rampino and Ambrose 274). However, the hourglass shaped bottleneck is dispreuted due to its timing of the expansion, which is proposed to have a minimum range of 50,000 years. Consquently, the super-eruption of Toba was unlikely to have resulted in the bottleneck (Rampino and Self 75). In addition to this, studies by McBrearty and Brooks on the Middle and Late Pleistocene human sites in Africa show that by 73.5 Ka, modern humans occupied a variety of habitats around the African continent. The human beings were also noted to be considerably adaptable and resourceful, with the ability to hunt and perform other tasks requiring skill (Westgate, Shane and Pearce). Conclusions In conclusion, it has been established that the super-eruption of Toba resulted in a severe climate change; however, there is inadequate evidence to support the notion that it caused a bottleneck in human population. Studies suggest that the effects were localized. In addition to this, research shows that the super-eruption had negligible effect on the Asian population, and none in Africa. During the time, human beings were adaptable, mobile and well equipped, which made them fully capable of handling the effects of the Toba phenomena. Moreover, the studies suggest that the super-eruption did not result in the extinction or decline of any fauna. Consequently, it is evident that the super-eruption of Toba did not result in human, flora or fauna bottleneck (Thornton 34). Figure 4: Sonar profiles along selected transect lines. Works Cited Ambrose, Stan ley H., Martin Anthony J. Williams and Umesh Chandra Chattopadhyaya. â€Å"Environmental impact of the 73 ka Toba eruption reflected by paleosol carbonate carbon isotope ratios in central India.† Quaternary International. 1.8 (2007): 167 –168. Print. Ambrose, Stanley H. â€Å"Did the super-eruption of Toba cause a human bottleneck? Reply to Gathorne-Hardy and Harcourt-Smith.† Journal of Hu man Evolutio. 45 (2003): 231 – 237. Print. Buhring, Christian and Michael Sarnthein. â€Å"Toba ash layers in the South China Sea: Evidence of contrasting wind directions during eruption ca. 74 ka.† Geology. 28 (2000): 275–278. Print. Chesner, C.A., Rose, W. I., Deino, A., Drake, R., Westgate, J.A. â€Å"Eruptive histo ry of earth’s largest Quaternary caldera (Toba, Indonesia) clarified.† Geology. 19 (1991): 200– 203. Print. De Silva, Shanaka. â€Å"Arc magmatism, calderas and supervolcanoes.† Geology. 36 (2008): 671 – 67 2. Print. Erwin, Douglas H. and T. A. Vogel. â€Å"Testing for causal relationships between large pyroclastic volcanic eruptions and mass extinctions.† Geophysical Research Letters. 19.9 (1992): 893–896. Print. Gasparotto, Giorgio, Elena Spadaforab, Vito Summac and Fabio Tateoc. â€Å"Contribution of grain size and compositional data from the Bengal Fan sediment to the understanding of Toba volcanic event.† Marine Geology. 162.2-4 (2000): 561 – 572. Print. Gates, Alexander E. and David Ritchie. Encyclope dia of Earthquakes and Volcanoes, 3rd edition. New York: Facts on File. 2007. Print. Gathorne-Hardy, F.J. and W.E.H Harcourt-Smith. â€Å"The super-eruption of Toba, did it cause a human bottleneck?† Journal of Human Evolution. 45 (2003): 227– 230. Print. Hawks, John, Keith Hunley, Sang-Hee Lee and Milford Wolpoff. â€Å"Population Bottle necks and Pleistocene Human Evolution.† Molecular Biology and Evolution. 17.1 (2000): 12–2 2. Print. Lang, C., M. Leuenberger and J. Schwander. â€Å"Rapid temperature variation in Central Greenland 70,000 years ago.† Science. 286 (1999): 934–937. Print. Jones, G.S., R.S.J.,Sparks and P.J. Valdes. â€Å"An AOGCM model of the climate response to a volcanic super-eruption.† Climate Dynamics. 25 (2005): 725 – 738. Print. Jones, M.T., R.S.J. Sparks and P.J. Valdes. â€Å"The climatic impact of supervolcanic ash blankets.† Climate Dynamics. 29 (2007): 553– 564. Print. Kelly, P.M., P.D. Jones and J. Pengqun. â€Å"The spatial response of the climate system to explosive volcanic eruptions.† International Journal of Climatology. 16 (1996): 537 – 550. Print. McBrearty, Sally and Alison S. Brooks. â€Å"The revolution that wasn’t: a new interpretation of the origin of modern human behavior.† Journal of Human Evolution. 39.5 (2000): 453–563. Print. Ninkovich, D., R.S.J. Sparks and M.T., Ledbetter. â€Å"Th e exceptional magnitude and intensity of the Toba eruption, Sumatra: an example of the use of deep-sea tephra layers as a geological tool.† Bulletin Volcanologique. 41.3 (1978): 1 –13. Print. Oppenheimer, C. â€Å"Limited global change due to the largest known Quaternary eruption?† Quaternary Science Reviews. 21.14-15 (2002): 1593 –1609. Print. Pattan, J.N., Phil Shane and V.K. Banakar. â€Å"New occurrence of youngest Toba tuff in abyssal sediments of the central Indian Basin.† Mar. Geol. 155 (1999): 243–248. Print. Petraglia, M., R., Korisettar, N., Boivin, et al. â€Å"Middle Pleistocene assemblages from the Indian subcontinent before and after the Toba super-eruption.† Science. 317 (2007): 114 –116. Print. Rampino, M.R. and S. Self. â€Å"Climate-volcanism feedback and the Toba eruption of 74 000 years ago.† Quaternary Research. 40 (1993): 269– 280. Print. Rampino, M.R. and S.H Ambrose. â€Å"Volca nic winter in the Garden of Eden: The Toba supereruption and the late Pleistocene human population crash.† Volcanic Hazards and Disasters in Human Antiquity: Geological Society of America. 345 (2000): 71 – 82. Print. Robock, A., C. Ammann, L. Oman, D. Shindell, S. Levis, and G. Stenchikov. â€Å"Did the Toba volcanic eruption of 74 ka B.P. produce widespread glaciation?† Journal of Geophysical Research (2009): 114. Print. Rose, W.I. and C.A. Chesner. â€Å"Dispersal of ash in the great Toba eruption, 75 ka.† Geology 15.10 (1987): 913– 917. Print. Sadler, J.P. and J.P. Grattan. â€Å"Volcanoes as agents of past environmental change.† Global and Planetary Change. 21.1-3 (1999): 181 – 196. Print. Samuel, M.A., N.A.Harbury, A. Bakri, F. Banner and L. Hartono. â€Å"A new stratigraphy for the islands of the Sumatran Forearc, Indonesia.† Journal of Asian Earth Sciences.15 (1997): 339–380. Print. Thornton, Ian.W.B. Krakatau, the destructio n and reassembly of an island ecosystem. Cambridge, Massachusetts and London: Harvard University Press. 1996. Print. Schulz, H., et al. â€Å"The Toba volcanic event and interstadial/stadial climates at the marine isotope stage 5 to 4 transition in the northern Indian Ocean.† Quaternary Research. 57 (2002): 22 – 31. Print. Westgate, J.A., et al. â€Å"All Toba tephra occurrences across peninsular India belong to the 75, 000 yr B.P. eruption.† Quaternary Research. 50 (1998): 107 –112. Print. Williams, M.A.J. and M.F. Clarke. â€Å"Late Quaternary environments in north central India.† Nature. 308 (1984): 633– 635. Print. Zielinski, Gregory A. â€Å"Use of paleo-records in determining variability within the volcanism-climate system.† Quaternary Science Reviews. 19.1-5 (2000): 417–438. Print. List of illustrations Tables Table 1: Particle size distribution of the YTT ash at the Rehi section, Son valley, India Figures Figure 1: Dist ribution of volcanic ash from the 73 ka Toba super-eruption showing location of marine cores and sections sampled in India Fig. 2: Tectonic setting and location map (inset) of the Toba Caldera Figure 3: Bathymetric map of Lake Toba. Depth is represented by isochromes; 100 m contour lines are plotted for reference. Figure 4: Sonar profiles along selected transect lines This research paper on The Eruption of Toba was written and submitted by user Nakia to help you with your own studies. You are free to use it for research and reference purposes in order to write your own paper; however, you must cite it accordingly. You can donate your paper here.

The film Psycho Essays

The film Psycho Essays The film Psycho Paper The film Psycho Paper Analyse the ways in which Alfred Hitchcock builds tension and fear in the shower scene in the film Psycho Robert Bloch first released Psycho in 1957 in form of a novel, but it was better known as a film directed and edited by the master of suspense, Alfred Hitchcock, and it was first released on big screens in 1960. The film was highly controversial at the time due to the strict morals and ethics enforced by the Motion Picture Association, but escaped the censorship laws due to numerous tricks that Hitchcock deployed, to bend the rules. Hitchcock got around Normans transvestite side, which along with homosexuality was taboo at the time, and by saying that Norman was not dressing up as a woman for sexual reasons so therefore was not a transvestite. These factors plus many more like the verity of camera angles, music and most importantly the plot helped Hitchcock to wheel in his audience to come and see Psycho. Throughout the film Psycho there are numerous techniques used that assisted Hitchcock to keep his audience in suspense and tension. One clear example, in the storyline is in the introduction. Never before on the big screens in the 1960s would the audience have ever dreamt to imagine a semi naked figure on screen, but when that is the dress status of the first two characters the audience are shocked and horrified, and this clever tactic would have kept his audience interested and poised in their seats. Hitchcock took advantage of his stunned audience and used a series of close and long moving shots to move in on Marion. This would have made his audience feel particularly uncomfortable because it would almost seem that they are spying on Marion, and her male companion. This different introduction would have lead the audience to believe the film would be about Marion and her male companions relationship. So, Hitchcock developed the story line and plots very cleverly, as the title of the film is called Psycho, the first ten to twenty minutes, the film resembled a romance story but then dramatically changed to a police enquiry, which would have lead to the Hitchcocks audience being engaged with the film as they are eager to find out more about Marion moreover the audience would be trying to figure out what the plot of the film actually was. And it is near the middle of the film the audience started to get vivid image of death, there were two stuffed birds of prey in Norman Bates office, where he offered Marion dinner when she took a pit stop at a motel called Bates Motel. One an owl and the other a crow which both represent death. This is one of the most meaningful and ironic scenes that are seen throughout the whole film. The position of the birds are very important as they are towered over Marion, which suggested perhaps that death is going to come to her soon. The room was very dark and Hitchcock had used dark coloured walls, to give a huge shadow effect on the birds, to give them a scarier and sinister look. A lot of tension was created in this particular scene but then when Marion starts the conversation she found it somehow relaxing. And without noticing Marion gave her real name when earlier she intentionally gave another. When she went into her room, Norman also went into the back of the office, and it is now when suspense in Psycho came combined with suspicion When Norman watched Marion through a peephole, Hitchcock was particularly clever at this point because the audience would brand Norman a weirdo and a pervert but would soon fell very strange, as they would be watching through his eyes, as if they were, the weirdo and not Norman. As Marion took her clothes off, the camera takes a shot of Marion standing in black underwear, which in the 1960s gives a symbol of wanting to have sex. Ironically, in the beginning of the film she was wearing white underwear which is a symbol of purity and cleanliness. This office scene was soon to be followed by an extraordinary and famous shower scene, which took Hitchcock seventy-one to seventy-eight different camera set ups to film. Which suggested that Hitchcock wanted the scene to be perfect. The shower scene took seven days to film and only lasted forty-five seconds. It opened with Marion taking off her robe for a shower. She was located in a white tile bathroom, which was brightly lit. All the natural sounds were emphasised; the toilet being flushed, soap packet being opened, movement of the shower and shower curtains. The audience could not predict a murder was about to happen because everything seemed superficially fine there are no real sign of foreboding. So when Marion took of her dressing gown and stepped into the bath, pulling the shower curtain across, normality was still sustained however the audience start to get a feeling of suspense and tension due to the lack of action. The camera angle at this scene is very important as the camera took a low angle shot and transferred to a high angle shot. The angle illustrated that characters identity was changing. This showed the audience that the character goes from being superior to powerless suggesting that something bad was about to happen. In addition, Marion having a shower suggested that she was washing away all her wrong doings to make herself to the audience as being deeply relaxed as she was smiling. Hitchcock gave tranquillity and calmness to the audience as he made them enjoy her shower. But to their sudden horror the bath room door opened and a figure appeared in the room. An over the shoulder shot was used as it prepared the audience for an attack, because they saw what Marion couldnt and this created a lot of eeriness in the atmosphere. Another over the shoulder shot was used, and suspense is further created as the figure advanced towards the shower, footsteps were not heard because of the loud sound effects of the water, and as the curtains were closed the audience couldnt see the figures face, which made the shot look like a surveillance camera. The calm and normal atmosphere was dramatically changed to being terrified as a shadow entered the bathroom with a large knife. Additionally, the frantic violin sounds added feeling of fear in the audience. And that fear effect was sustained as Marion fought and screamed for her life. Close up of Marions face allowed the audience to see and feel the pain she went through. The thriller genre is clearly identified in this particular scene. Marion soon disappeared off the screen making the audience focus and concentrate on the dark, disturbing figure. Hitchcock made the audience believe that the figure was the mother of Norman due to the shape of the hair, which is shown in silhouette. Rapid shots were shown of the killing, and several of those shots were of Marion moving form side to side and struggling to defend herself to show that she can not stop her killer. The camera swooped in with a high angled shot, which emphasised Marions blood draining away in the bath. The extreme close up of Marions hand allowed the audience to see how slowly and painfully she was dying. This aroused emotional thoughts within the audience. The audience were shocked because they knew Marions been attacked. They see the upper part of the body and her facial expressions. The high angled camera shot of Marion falling forward made Marion appear smaller which lead to her beginning to appear off the screen. This unique scene built up the tension in the audience, and image of her eyes filling the whole screen is frightening as the eye becomes lifeless and emotionless The music and the sound effects in the film Psycho also played and important role in creating tension in the audience. Hitchcock slowed down the tempo of the film, due to the fact it would have made the audience feel more shocked at the sudden death of Marion. The violin and cello in Psycho was so effective because it is used as percussion suggesting the knife strokes. Deep sounds also sound percussive, and the audience could feel them literally piercing their body. This clever method would have sent shivers to the audience. In order for Hitchcock to create fear in the minds of the audience he had to use both the fast camera angle shots and the sharp, high pitch of the music to sustain and capture the audiences fear. This in the 1960 would have made the hairs on the back of the audience stand up, but now in the new millennium the audience are prepared and have seen more horrifying films, to be frightened from Psycho. Consequently Psycho led the path in film history, and it has made horror films what they are now.

Graduation Speech of Pupils Essay Example | Topics and Well Written Essays - 500 words - 1

Graduation Speech of Pupils - Essay Example Indeed the education is expensive but it is even more expensive to play ignorant. Our parents have done everything not just pay our school fees but also provide us with the basic needs and see us to through our studies in a smooth manner. Teachers on their part have on a daily basis held our hands as we walk past the many milestones that define our eleven year journey of education. You taught us in class, you taught us out of class, offered moral support and encouraged us never to give up on our dreams. Surely, you teachers and parents have denied yourselves a lot and given to us more than enough. We have no better words thank you. I want to say that as we graduate, we need not be awarded with medals so as to prove that there is something very special within us. We are all blessed, talented and are worth a part on the back. This day is all about celebrating the talents and knowledge that walk away with as we graduate. I guess all for a long time have been imagining what the graduation day would look like. I admit that personally, I have vivid memories of every imagined scene about this day. To my fellow classmates, I must emphasize that this has been long journey marked with hard work so as to come out of here as changed persons. We did not imagine surviving the roller coaster ride of schooling and being here to celebrate eventually. Indeed this has been a long journey. As I come to the end, I must say what we are now through with is just but a milestone and it that time for us to move on to even bigger fights for our lives. All we learned in class and out of class while here will give us the base to stand on as get through the next stages of education. We learned not only formulas, poems, and other things in class but also life skills outside class. We learned how to work independently, in teams and more importantly to appreciate our friends in their uniqueness. Everything we