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University Degree: Geology
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A Natural hazard has been defined by the United Nations educational, Scientific and Cultural Organisation (UNESCO) as "the given probability of occurrence within a specified period of time and within a given area of potentially damaging phenomenon". This definition however is misleading, as not all geologic hazards are natural. Some geologic hazards can be influenced by human activity. A better definition would be "A naturally occurring or man-made condition or phenomenon that presents a risk or is a potential danger to life and property" (Science Glossary, 2006).
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Nonliving reservoirs include the atmosphere, the crust, and the ocean, while living reservoirs include plants, animals and microbes" (2001 712). For Kemp a biogeochemical cycle is one in which an element "moves between sources and sinks along well established pathways. To facilitate progress through the cycle, it may change state - from a liquid to a gas for example - often in combination with other chemicals and involve both organic and inorganic phases" (Kemp 2004: 64). In an 'open system' resources are supplied constantly and the process ceases when the inputs are exhausted.
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"A complete understanding of the extent and chronology of Quaternary glaciation requires evidence from both terrestrial and marine evidence - discuss."
cores from ice sheets) for an even broader source range. Marine Evidence Ocean sediments provide a very much more complete geological record (Press and Siever 2000), partly due to the highly efficient preservation of sediment (Lowe and Walker 1997). Striae for example are best protected from weathering in sub marine conditions (or, when exposed to the surface, covered in 0.4-0.5m of till) (Kleman 1990). However, the top 50cm of sediment can be subject to bioturbation from marine organisms effectively 'blurring' the information.
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Much of the earth's surface especially the crust of the ocean floor consisted of very young rocks, geologically. The rocks came from long lines of volcanoes, which were located along ridges near centres of ocean basins, within the last 300 million years. When this was concluded the theory of plate tectonics was developed, this explained the locations and distributions of volcanoes on Earth. Volcanoes that erupted basalt tended to be located along midocean ridges, this marks constructional margins of Earth's rigid crust plates. There are several ways in which a volcano forms, just as there are several different kinds of volcanoes. Hot magma, rising from lower reaches of the Earth, eventually, but not always, erupts onto the surface.
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The dangers secondary effects pose to a location can be as great the initial blast or eruption. Pyroclastic currents and lahars are not the only secondary effects that cause problems, actually there are so many that it would take much to long to explain them all. So we will limit this subject to ones dealing directly with the eruption of Mt. St. Helens. Along with lahars and PDC's there are ash plumes, debris avalanches and volcanic gases. Ash plumes create massive amounts of tephra fallout creating all sorts of instrumental problems.
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Discuss the Contention that Landscape Development is Largely Driven by Periods of Tectonic Activity.
This essay will also attempt discuss to what extent these geomorphologists see tectonic activity as a primary role in landscape development. Tectonic activity also produces its own landforms. Not only is it responsible for continental positioning but also features such as volcanoes and fault lines. One major feature of tectonic activity is deep ocean trenches. When two oceanic plates collide, it results in the creation of a volcanic island arc and the formation of an ocean trench. The Philippine Island Arc zone and the Tongan Island Arc zone are examples of these.
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The lithosphere is capped by the crust, the final layer of the earth. This is a less dense layer and very thin in comparison to the core and mantle. There are two types of crust, being oceanic and continental. Continental crust is generally thicker and less dense than oceanic. Plate tectonics are concerned with the movement of lithospheric plates, which are chunks of lithosphere with their crustal caps. The earth's surface consists of seven major and thirteen minor plates. The boundaries between these plates can be described as divergent, convergent or transform.
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to east (pre-Cambrian). These are volcanic rocks which form the majority of the headland to the north, St. David's Head. However several boulder sized Pre-Cambrian rock pieces were found at Settling Noses. These rocks were green and had rhombic crystals under examination. The rock is therefore classified as rhom porphyry. This rock is described as an erratic as it is so dissimilar to the rock type of the landscape it is found in. A glacier has most likely moved it, as the only other possible mechanism for movement is a river, which is unlikely, as it would have been sorted to the bottom of a fluvial deposit.
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The San Andreas Fault occurs on a conservative plate margin. The oceanic crust, the pacific plate and the continental crust, the North American plate are moving parallel to each other. As the two plates move past each other, friction causes pressure to build up. The pressure is eventually released causing the two plates to jerk forward, sending seismic waves through the earth. These waves are released at the epicentre causing earthquakes. The San Andreas runs 1200km through the length of California. The fault is seen as a potential threat to many large Californian cities, such as Los Angeles and San Francisco.
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I also understand that plagiarism and collusion are serious offences and that if I am guilty of either my work may be disqualified and I may face other disciplinary action. Signed: ........ Date: 24/03/03..................... The Role of Wnt Signalling in Neural Crest Development Noel Slattery w0036323 The neural crest is a transient structure that extends along the rostro-caudal axis of developing vertebrate embryos. It comes into existence during the final stages of neurulation. The primary embryonic induction initiates and controls neurulation.
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These volcanoes, which can be subdivided into Hawaiian, Icelandic and Galapagos types, have one thing in common, that they are made up of very fluid, non-viscous basaltic lava. The rapid accumulation of successive flows of this lava leads to a volcano with shallow sides, steeper near the flanks as the lava cools and needs more of a gradient to continue to flow (See figure 2). Hawaiian shields are the largest of the three types; it is thought that the total volume of Mauna Loa is around 40,000 cubic kilometres ( Williams & McBirney, 1979 ).
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which terminated its activity with a summit caldera collapse, and the recent cone (Mount Vesuvius) that has grown inside the Somma caldera and whose last eruption dates back to 1944 (Tazieff and Sabroux 1983: 149)." The present day Vesuvius is surrounded by many towns and villages, and is home to nearly 4 million people; if the volcano had not arisen here, the land would not have been able to support, "more than a tenth of the present population (Lobley c.1889: 48)."
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However, some background information about the Earth is needed. The crust consists of many tectonic plates (see map below) A map of the Earth's tectonic plates When these plates rub against, or collide with each other, they often cause an earthquake. This releases energy as sound waves. These waves then travel through the Earth in two main forms, Primary (P) and Secondary (S). Primary waves are longitudinal waves, meaning that the wave action is parallel to the motion. Secondary waves are transverse waves, meaning that the wave action is at 90? to the direction of motion. Primary waves travel faster than Secondary waves.
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Discuss the following within the context of quaternary environmental change: 1). Biological proxies2). Milankovitch cycles3). Reconstruction of former ice flow directions
The main purpose of pollen reconstruction is that it provides a link between higher (tree rings) and lower (terrestrial and oceanic) resolution records. It is also possible to map how individual species have migrated over time such as the information available on the deciduous oak tree in Europe. During the LGM, 18,000 B.P. it is known that oak trees only survived in southern Europe in countries such as Spain, Italy and Turkey. During this period the trees managed to secure 'reservoirs' known as refugia, which then, as the climate gradually warmed and the ice melted, allowed the trees spread northward.
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CLASSIFICATION OF MAP PROJECTIONS: There are two ways of classifying map projections. The first is based on the principle involved in their mode of development and the second is based on the group or family to which they belong. 1. CLASSIFICATION BASED ON THE MODE OF THEIR DEVELOPMENT: Under this scheme we have flowing map projections: I. Perspective map projections II. Non-perspective map projections III. Conventional map projections I. PERSPECTIVE MAP PROJECTIONS: The word perspective in the usual sense means the art of representing solid objects on a flat surface in such a way as to give the same impression of relative distance, size, etc., as the objects themselves do when viewed from a certain point.
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America. Made up of continent and oceanic lithosphere to east- continues to the mid ocean ridge. - Passive continental margin - Broad, gently seaward-dipping continental shelf o Continental lithosphere is welded onto the oceanic beneath the continental shelf - Active continental margin - Ocean - continent boundary is convergent margin therefore a subduction site. Pacific coast of No-West American What drives Plate Tectonics? Geothermal heat flux - heat escapes to the surface mostly through mantle convection Origin of heat in Earth's interior: 1.
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Pembrokeshire Geology Field Trip Report. The Caerfai shale has a red/pink colour due to the presence of oxidised iron
The Caerfai shale has a red/pink colour due to the presence of oxidised iron. It is a fine-grained sedimentary rock with some mineral veins present. The mineral veins are approximately 3cm thick. Crystaline tuff is present throughout the rock, which is consolidated volcanic ash in which crystals and crystal fragments predominate. The shale consists of 90 percent mud and 10 percent silt. Organisms have removed sedimentary structures, as the rock is bioturbated. Laminations, flame structures, load structures and asymmetrical ripples were present throughout the shale. Finally, trace fossils in the form of vertical burrows were present running through the ash.
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