Volcanoes in Human History - Book Report/Review Example

Volcanoes in Human History: The Far-reaching Effects of Major Eruption This book basically describes major volcanic events that have happened on earth from a different period in time. It digs deep in major volcanic occurrences and the consequences to the human population and other forms of life on earth. Developments in volcanicity are ranged according to magnitude and their major geological changes (DeBoer, Jelle Z, and Donald T 2002 page1). The authors also present methods of dating used to approximate when these devastating volcanicity occurred. The intensity of a volcanic eruption is clearly are the causes catastrophic losses and geological metamorphism. Furthermore, the book describes the whole process of volcanicity and resultant features formed after cooling of magma. The book tries to unravel the major causes of volcanicity in various geographical places. According to this book, people who were living close to active volcanic mountains were most affected; the violent eruption did not only pollute the air, block rivers but also killed many individuals due to silent lava flow. Generally all forms of life are adversely affected during a volcanic eruption. The ancient human race associate volcanicity with super natural power, seen as a form of punishment from deities while others believe it was hell breaking loose. However, geological science cleared the disapproved the belief by putting forth comprehensive explanation. In this book, volcanicity is as a result violent ejection of magma from the earth interior. Once there is isotactic imbalance and a fissure created, magma is pushed out of under high pressure, once it reaches the surface it flows as lava that forms various physical features. Magma is destructive due to its unbearable temperature. Volcanic lava destroys anything on its path, causing landslides and mudflows that quickly cover long distances (DeBoer, Jelle Z, and Donald T 2002 page 26). Volcanic materials can interfere with weather pattern for a number of days or even months. However, volcanic eruption are not entirely disastrous, it promotes water cycle by bring clean underground water to the surface, resulting in formation of large volcanic water bodies. Volcanic eruption also exposes mineral ore and emission of natural gas. Molten materials form the lava, gases and fragments that are the main products of volcanic eruption. Magma moves in an upward direction due to its temperature and gaseous component compared to solid rock. Rapid lava cooling forms rocks with large mineral crystals. Erupted materials fall into three major categories; the dense materials are fresh magma fragments, pumice and older volcanic agglomerates derided from the flanks of volcano falling on ground (DeBoer, Jelle Z, and Donald T 2002 page 29). The second class contains fiery gaseous rushes made up of droplets of fresh molten materials, this type of volcanic products move swiftly as they have less density. The third class of volcanic products is dust that makes buoyant plumes that escalate many meters into the atmosphere. Volcanoes have life cycles just like living things, in February 20th 1943 Dionisio Pulido, a Mexican farmer, witnessed the development of a volcano. What was initially a depression in the corn field developed a fissure from which sulfurous clouds emerged. The place had a cider cone over 10 meters high the following morning. In a week’s time the feature had raise to 170 meters, named as Paricutin. Young volcanoes are conspicuously sleek, and symmetrical cones while old volcanoes are irregular, worn out peaks and eroded at the foot. Volcanoes are known to erupt in a spasmodic pattern, each eruption increasing in strength or decreasing. Hence eruption can occur for weeks to a couple of years (DeBoer, Jelle Z, and Donald T 2002 page 135). At the top of volcanic mountains are craters, these depressions can hold water forming crater lakes or remain empty. Craters come as a result of the inward collapse of volcanic mountains due to void created by expulsion of magma. Geologists noted that plate tectonics contribute to active volcanicity. Balance between sial and sima, which are the major earth surface layers cause significant movement in terms of centimeter and even meters. Isostactic imbalance triggers earthquakes which create fissures that are outlets for magma, hence volcanicity. Tectonic plates often collide as they move (DeBoer, Jelle Z, and Donald T 2002 page 109). Consequences of collision are always unfathomed. Subduction occurs, one place moves down wards into the asthenosphere as the other rises. The subducted plate is subjected to heat and pressure that make the rocks to melt forming part of magma. Magma is formed when subducted plate is pushed further into asthenosphere up to a distance of 150 kilometers. The interior pressure and heat liquefy the rocks within the plate, emitting gases and water collectively called magma. Magma moves in a convection form, part with highest temperature rising as the colder part descends under pressure. Continuous magma cycle builds up pressure which makes it erupt once an outlet is created. Volcanic activities have been happening time immemorial, the resultant physical features stand as undisputed evidence for this powerful work of nature. Some of the features include. There is a chronological and elaborate record of major volcanic eruption. The authors have tried to give comprehensive information on the time of occurrence, the geographical location as well as consequences to humanity. Major eruptions recorded in this book include (DeBoer, Jelle Z, and Donald T 2002 page 17); Tristan da Cunha in 1961moderate in intensity, Surtsey 1963 in Iceland with moderate intensity, Eldfell in Iceland 1973, moderate intensity, Kilauea-Hawaii c 1790 large intensity, Laki in Iceland 1783 with large intensity,Pelee in Martinique 1902 large intensity and Mount St.Helens in United State 1980 with very large intensity. Other major recorded eruptions are;Vesuvius in Italy 79 with huge intensity,Thera in Greece c1620B.P with humongous intensity,Krakatau in Indonesia 1883 huge intensity,Tambora in Indonesia 1815 with colossal intensity and Toba in Indonesia c.74000 B.P with humongous intensity. This book further explains on methods used for dating volcanoes (DeBoer, Jelle Z, and Donald T 2002 page 19);. Paleomanetism is a dating method that approximates the time of magnetic fields when lava was molten. It gives a correlation between the alignment of the earth’s magnetic fields in the past and lava flow. Carbon-14 dating is the popular dating method. It determines the amount of radioactivity triggered by isotopes of certain chemicals. Carbon 14 isotopes are in organic materials revealing the age of a rock and possible time when volcanic eruption occurred. Most interesting facts from learnt are the process of volcanicity, formation of magma, resultant physical features of eruption, the causes of volcanic eruption, continental distribution of volcanic features effects of volcanicity and methods of dating volcanic features. Work cited DeBoer, Jelle Z, and Donald T. Sanders. Volcanoes in Human History: The Far-Reaching Effects of Major Eruptions. Princeton, NJ [u.a.: Princeton Univ. Press, 2002. Print Read More