arth’s crust is the outermost solid shell of rocky planet. Geographers say that the crust has a layer of igneous rock as well as sedimentary rocks. The crust also has some metamorphic, igneous and sedimentary that either form the ocean crust or the continental crust. The earth’s crust is very important to human beings not only because they live in it but because of the socio-economic benefits it offers them. This essay attempts to highlight the salient socio-economic significance of the earth’s crust. It will start by explaining what the crust is and then proceed to discuss the benefits enjoyed from it by humans and other species be it plant or animal kingdom.
Robinson (2011) argues that the crust of the Earth is composed of a great variety of igneous, metamorphic, and sedimentary rocks.
The boundary between the crust and mantle is conventionally placed at the Mohorovič discontinuity, a boundary defined by a contrast in seismic velocity. The crust occupies less than 1% of Earth's volume and is divided into two parts. The ocean crust is predominated full of minerals such as Silica and Magnesium hence SIMA of the sea is different .The continental crust is approximately around 30 km to 50 km thick and is mostly composed of slightly less dense rocks than those of the oceanic crust. Some of these less dense rocks, such as granite, are common in the continental crust but rare to absent in the oceanic crust. Both the continental and oceanic crust mantle. The Conrad discontinuity separates the SIAL(silica and aluminium) from the SIMA. (silica and magnesium).
Robinson further states that the continental crust is thicker such that it extends both above and below the oceanic crust. The slightly higher elevation of the continental crust causes the water to run off the continental to the oceans.
Herndon (1980) views that one of the salient significance is that the crust supports living organism in the soil on which man depends. Part of the living organisms on the earth’s crust are the forests which comprises of all the wild flora and fauna which directly and indirectly are of economic importance to man. Forests are source of all the products like fruits, timber, and fuel wood, resins gums etc. This supports the values of values of biodiversity. The services rendered by the biodiversity are essential for the functioning of the global economy. The biodiversity also has great importance as a direct source of income and economic development. Simply put we eat the earth. The chief economic product of forests is timber. Wood pulp from timber is the primary source of raw material for paper industry. Forests also provide raw material for a number of other industries like the manufacture of sports goods and matches. Many kinds of pharmaceuticals, rayon and other useful materials like gums, resin, turpentine charcoal, firewood and oil come from the forests that grow on top of the soil.
The other importance is the crust contains bituminous, a resource used for road surfacing is embedded in the crust. Robinson (2011) argues that, “… bituminous materials are still used extensively in construction; they retain their excellent adhesive and waterproofing properties. . .” He further highlights that the adhesiveness of bitumen to a surface depends upon both the nature of the surface and the state of the bitumen. For an adhesive to act it must be able to wet a surface. In fluid state bitumen can wet a dry solid surface and good adhesion will result, but the presence of water will prevent adhesion. The temperatures of the solid and the bitumen also influence the bond.
Another interesting importance of the earth’s crust is that it is the bridge between life and death as the dead return to the earth’s crust at burial. Burial or interment is the ritual act of placing a dead person or animal, sometimes with objects, into the ground. This is accomplished by excavating a pit or trench, placing the deceased and objects in it, and covering it over. Intentional burial, particularly with grave goods, may be one of the earliest detectable forms of religious practice since prehistoric. For Lieberman (1991) the crust signifies a "concern for the dead that transcends daily life."
The fact that flowers grow on both the continental and oceanic crusts is another importance. Flowers which enhances nature’s beauty thrives on the earth’s crust. Sattler, (1973) writes that a flower, sometimes known as a bloom is the reproductive structure found in flowering plants. The plants may grow on the continental and oceanic crusts. He further writes that, “In addition to facilitating the reproduction of flowering plants, flowers have long been admired and used for beautification of their environment, and also as objects of romance, ritual, religion, medicine and as a source of food.”
Lovely beauty on the earth’s crust enhances tourism which further enhances the social life of the people. Tourism is travel for recreation, leisure, religious, family or business purposes, usually for a limited duration. Tourism is “traveling to and staying in places outside their usual environment for not more than one consecutive year for leisure, business and other purposes". World Tourism Organistion (1995). Tourism has become a popular global leisure activity. Today, tourism is a major source of income for many countries, and affects the economy of both the source and host countries, in some cases being vital importance.
Robinson (2011) argues that almost all Earth materials are used by humans for something. We require metals for making machines, sands and gravels for making roads and buildings, sand for making computer chips, limestone and gypsum for making concrete, clays for making ceramics, gold, silver, copper and aluminum for making electric circuits, and diamonds and corundum (sapphire, ruby, emerald) for abrasives and jewelry. Minerals endowed in the earth’s crust are ideal for development. There are over 3000 minerals known. Some are rare and precious such as gold and diamond, while others are more ordinary, such as quartz. Mining activities on earth’s crust are also associated with direct economic benefits, which allow for the development and growth of the citizens prosperity. So far, the positive impact of mining on the environment has been ignored. Whereas, post-mining areas form new ecosystems, often of higher biodiversity, with many rare or protected species of plants. In addition, these areas are enriched the geological environments which have scientific and educational values, unique in the region or country . Herndon (1980)
The other importance of the earth’s crust as highlighted by Mitchell (2010) lies in the fact that the continental crust also supports agriculture. The production of biomass by agriculture and forestry. The filtering of Crops man feeds on for his survival grow on the earth crust. Agriculture is by far the most widespread form of human activity and it is more basic than any other industry. Its yields fibers and raw materials for the factories on which a large portion of the remaining people depend. From the crops the farmers grow he gets his food and also that of his family. The surplus is sold for cash, with which he buys the necessities of life. Without agriculture, many factories would close, and despite all wonders that science has brought, a world without food would be dead world.
The oceanic crust is generally endowed with abundant water resources that amount to nine percent of the global freshwater resources. There is however uneven distribution of this resource, between areas of severe aridity with limited freshwater resources like the Sahara and Kalahari deserts in the northern and southern parts, to the tropical belt of mid-Africa with abundant freshwater resources. This distribution also follows the pattern of rainfall variability – in time and space – in the region, UNEP (2006). Most water resources occur in the form of rivers, lakes, wetlands, and limited but widespread groundwater. Water is life as they say. In water aquatic life for fish is plenty.
Lastly, People find a living out of what the crust has to offer and man’s mode of living is to some extent determined by the underlying strata. UNEP (2006) writes that reliance on land as a principal source of livelihoods and as a basis for economic development in Africa is likely to persist in the foreseeable future. The paper further states that holiday options are influenced by the presence of viable landforms, for example desert crossing or rapid surfing.
In a nutshell, the earth’s crust holds great deal of socio-economic significance in so many ways that it forms the platform on which both the animate and the inanimate carry out the necessary processes for equilibrium and survival. This goes on and on as long as time is there. Indeed the crust is significant as highlighted as above.
REFERENCES
Herndon, J. M. (1980) The chemical composition of the interior shells of the Earth. Proc. R. Soc. London.
Http//www.enchantedlearning.com
Mitchell, W. (2010) Jamaica Ministry of Agriculture Rural Agricultural Development Authority, In J. Richards, (ed.), Savanna-la-Mar. Conversation dated February 2, 2010. Kingston.
Philip, L. (1991) Uniquely Human, Harvard University Press, Massachusetts.
Robinson, E. C. (2011) http://pubs.usgs.gov. Retrieved November 26, 2014 @ 12:43
Sattler, R. (1973) Organogenesis of Flowers. A Photographic Text-Atlas. University of Toronto Press, Toronto.
UNEP. (2006) Africa Environment Outlook 2: Our Environment, Our Wealth, London.
World Tourism Organization. 1995. Retrieved November 24, 2014
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