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Scattered around the globe are more than one hundred regions of volcanic activity known as hot spots. Unlike most volcanoes, hot spots are rarely found along the boundaries of the continental and oceanic plates that comprise the Earth’s crust; most hot spots lie deep in the interior of plates and are anchored deep in the layers of the Earth’s surface. Hot spots are also distinguished from other volcanoes by their lavas, which contain greater amounts of alkali metals than do those from volcanoes at plate margins.In some cases, plates moving past hot spots have left trails of extinct volcanoes in much the same way that wind passing over a chimney carries off puffs of smoke, it appears that the Hawaiian Islands were created in such a manner, by a single source of lava, welling up from a hot spot, over which the Pacific Ocean plate passed on a course roughly from the east toward the northwest, carrying off a line of volcanoes of increasing age. Two other Pacific island chains — the Austral Ridge and the Tuamotu Ridge — parallel the configuration of the Hawaiian chain; they are also aligned from the east toward the northwest, with the most recent volcanic activity near their eastern terminuses.That the Pacific plate and the other plates are moving is now beyond dispute; the relative motion of the plates has been reconstructed in detail. However the relative motion of the plates with respect to the Earth’s interior cannot be determined easily. Hot spots provide the measuring instruments for resolving the question of whether two continental plates are moving in opposite directions or whether one is stationary and the other is drifting away from it. The most compelling evidence that a continental plate is stationary is that, at some hot spots, lavas of several ages are superposed instead of being spread out in chronological sequence. Of course, reconstruction of plate motion from the tracks of hot-spot volcanoes assumes that hot spots are immobile, or nearly so. Several studies support such an assumption, including one that has shown that prominent hot spots throughout the world seem not to have moved during the past ten million years.Beyond acting as frames of reference, hot spots apparently influence the geophysical processes that propel the plates across the globe. When a continental plate comes to rest over a hot spot, material welling up from deeper layers forms a broad dome that, as it grows, develops deep fissures. In some instances, the continental plate may rupture entirely along some of the fissures so that the hot spot initiates the formation of a new ocean. Thus, just as earlier theories have explained the mobility of the continental plates, so hot-spot activity may suggest a theory to explain their mutability.1. The primary purpose of the passage is to( ).2. According to the passage, hot spots differ from most volcanoes in that hot spots( ).3. It can be inferred from the passage that evidence for the apparent course of the Pacific plate has been provided by the( ).4. It can be inferred from the passage that the spreading out of lavas of different ages at hot spots indicates that a( ).5. The passage suggests which of the following about the Hawaiian Islands, the Austral Ridge, and the Tuamotu Ridge?6. Which of the following, if true, would best support the author’s statement that hot-spot activity may explain the mutability of continental plates?7. The author’s argument that hot spots can be used to reconstruct the movement of continental plates is weakened by the fact that( ).8. The author’s style can best be described as( ).

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The energy contained in rock within the earth’s crust represents a nearly unlimited energy source, but until recently commercial retrieval has been limited to underground hot water and/or steam recovery systems. These-systems have been developed in areas of recent volcanic activity, where, high rates of heat flow cause visible eruption of water in the form of geysers and hot springs. In other areas, however, hot rock also exists near the surface but there is insufficient water present to produce eruptive phenomena. Thus a potential hot dry rock (HDR) reservoir exists whenever the amount of spontaneously produced geothermal fluid has been judged inadequate for existing commercial systems.As a result of the recent energy crisis, new concepts for creating HDR recovery systems — which involve drilling holes and connecting them to artificial reservoirs placed deep within the crust — are being developed. In all attempts to retrieve energy from HDR’s, artificial stimulation will be required to create either sufficient permeability or bounded flow paths to facilitate the removal of heat by circulation of a fluid over the surface of the rock.The HDR resource base is generally defined to include crustal rock that is hotter than 150℃, is at depths less than ten kilometers, and can be drilled with presently available equipment. Although wells deeper than ten kilometers are technically feasible, prevailing economic factors will obviously determine the commercial feasibility of wells at such depths. Rock temperatures as low as 100°C may be useful for space heating; however, for producing electricity, temperatures greater than 200°C are desirable.The geothermal gradient, which specifically determines the depth of drilling required to reach a desired temperature, is a major factor in the recoverability of geothermal resources. Temperature gradient maps generated from oil and gas well temperature depth records kept by the American Association of Petroleum Geologists suggest that tappable high-temperature gradients are distributed all across the United States. (There are many areas, however, for which no temperature gradient records exist.)Indications are that the HDR resource base is very large. If an average geothermal temperature gradient of 22°C per kilometer of depth is used, a staggering 13,000,000 quadrillion B. T. U.’ s of total energy are calculated to be contained in crustal rock to a ten kilometer depth in the United States. If we conservatively estimate that only about 0.2 percent is recoverable, we find a total that is comparable to the estimated resource base of all the coal remaining in the United States. The remaining problem is to balance the economics of deeper, hotter, more costly wells and shallower, cooler, less expensive wells against the value of the final product, electricity and/or heat.1. The primary purpose of the passage is to( ).2. The passage would be most likely to appear in a( ).3. According to passage, an average geothermal gradient of 22°C per kilometer of depth can be used to( ).4. It can be inferred from the passage that the availability of temperature-depth records for any specific areas in the United States depends primarily on the( ).5. According to the passage, in all HDR recovery systems fluid will be necessary in order to allow( ).6. According to the passage, if the average geothermal gradient in an area 22°C per kilometer of depth, which of the following can be reliably predicted?I. The temperature at the base of a 10-kilometer well will be sufficient for the production of electricity.II. Drilling of wells deeper than 10 kilometers will be economically feasible.III. Insufficient water is present to produce emotive phenomena.7. Which of the following would be the most appropriate title for the passage?

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The recorded civilization of India is one of the longest in the course of world history, and its mythology, linked to its religions and to the development of its civilization, spans an even greater length of time. Unlike the mythology of most countries, particularly Western countries, Indian mythology is still a part of the living culture of the people on all levels of society, from the illiterate masses to the educated elite.The Indians have always tended to retain early beliefs and mold them to reflect new social conditions or to fit these early beliefs into a new philosophical scheme. This tendency has led to a polytheism in which the number of deities and the myths attached to them are constantly increasing, despite attempts over the centuries of priests and philosophers to impose pantheism, or monotheism on the people. Another failure of the priest-hood has been to eradicate the caste system, which has been outlawed but which is legitimized by Indian mythology.Indian mythology is truly a living mythology, evolving as a consequence of historical circumstances like, dynastic changes, economic conditions, and the resultant social upheavals experienced by the Indian people. In other words, the mythology changes to explain and record actual historical events.However, history has not been the only element at work in changing and mythologizing Indian religion. Another less openly acknowledged factor has been the efforts of the priests, or Brahmins to maintain or increase their power and influence with the masses by weaving their primitive deities into the fabric of the Brahmins’ more sophisticated religion by means of myth. In this way, the Brahmins, which were not political rulers, maintained and consolidated their power over the masses and thereby ensured their own positions of trust and prestige with the emperor class.1. Indian mythology( ). 2. Ancient beliefs and myths( ).3. Indian religion is( ).4. The caste system is( ).5. The number of gods in Indian mythology is( ).6. Historical circumstances like dynastic changes and invasions are( ).7. Historically, Brahmins have been( ).

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