General English Admission Test For Non-English Major

Ph.D. program

(Harbin Institute of Technology)

Passage One

Questions 1-7 are based on the following passage:

According to a recent theory, Archean-age gold-quartz vein systems were formed over two billion years ago from magmatic fluids that originated from molten granitelike bodies deep beneath the surface of the Earth. This theory is contrary to the widely held view that the systems were deposited from metamorphic fluids, that is, from fluids that formed during the dehydration of wet sedimentary rocks. The recently developed theory has considerable practical importance. Most of the gold deposits discovered during the original gold rushes were exposed at the Earth’s surface and were found because they had shed trails of alluvial gold that were easily traced by simple prospecting methods. Although these same methods still leas to an occasional discovery, most deposits not yet discovered have gone undetected because they are buried and have no surface expression.

The challenge in exploration is therefore to unravel the subsurface geology of an area and pinpoint the position of buried minerals. Methods widely used today include analysis of aerial images that yield a broad geological overview, geophysical techniques that provide data on the magnetic, electrical, and mineralogical properties of the rocks being investigated, and sensitive chemical tests that are able to detect : the subtle chemical halos that often envelop mineralization. However, none of these high-technology methods are of any value if the sites to which they are applied have never mineralized, and to maximize the chances of discovery the explorer must therefore pay particular attention to selecting the ground formations most likely to be mineralized. Such ground selection relies to varying degrees on conceptual models, which take into account theoretical studies of relevant factors.

These models are constructed primarily from empirical observations of known mineral deposits and from theories of ore-forming processes. The explorer uses the models to identify those geological features that are critical to the formation of the mineralization being modeled, and then tries to select areas for exploration that exhibit as many of the critical features as possible.

1. The author is primarily concerned with . A. advocating a return to an older methodology. B. explaining the importance of a recent theory.

C. enumerating differences between two widely used methods D. describing events leading to a discovery

2. According to passage, the widely held view of Archean-age gold-quartz vein

systems is that such systems

A were formed from metamorphic fluids. B originated in molten granitelike bodies C were formed from alluvial deposits D generally have surface expression

3. The passage implies that which of the following steps would be the first

performed by explorers who wish to maximize their chances of discovering gold?

A Surveying several sites known to have been formed more than two billion

years ago.

B Limiting exploration to sites known to have been formed form metamorphic

fluid.

C Using an appropriate conceptual model to select a site for further exploration. D Using geophysical methods to analyze rocks over a broad area.

4. Which of the following statements about discoveries of gold deposits is supported by information in the passage?

A The number of gold discover made annually has increased between the time of the original gold rushes and the present

B New discoveries of gold deposits are likely to be the result of exploration techniques designed to locate buried mineralization

C It is unlikely that newly discovered gold deposits will ever yield as much as did those deposits discovered during the original gold rushes.

D Modern explorers are divided on the question of the utility of simple prospecting methods as a source of new discoveries of gold deposits.

5. It can be inferred from the passage that which of the following is easiest to detect?

A A gold-quartz vein system originating in magma tic fluids. B A gold-quartz vein system originating in metamorphic fluids. C A gold deposit that is mixed with granite. D A gold deposit that has shed alluvial gold.

6. The theory mentioned in line I relates to the conceptual models discussed in the passage in which of the following ways?

A It may furnish a valid account of ore-forming processes, and hence, can

support conceptual models that have great practical significance.

B It suggests that certain geological formations, long believed to be mineralized,

are in fact mineralized thus confirming current conceptual models.

C. It suggests that there may not be enough similarity across Archean-age

gold-quartz vein systems to warrant the formulation of conceptual models. D It corrects existing theories about the chemical halos of gold deposits, and

thus provides a basis for correcting current conceptual models.

7. According to the passage methods of exploring for gold that are widely used

today are based on which of the following facts?

A Most of the Earth’s remaining gold deposits are still molten.

B Most of the Earth’s remaining gold deposits are exposed at the surface.

C Most of the Earth’s remaining gold deposits are buried and have no surface

expression

D Only one type of gold deposit warrants exploration. since the other types of

gold deposits are found in regions difficult to reach

Passage Two

Questions 8-15 are based on the following passage:

In choosing a method for determining climatic conditions that existed in the past, paleoclimatologists invoke four principal criteria. First, the material—rocks, lakes, vegetation, etc.—on which the method relies must be widespread enough to provide plenty of information, since analysis of material that is rarely encountered will not permit correlation with other regions or with other periods of geological history. Second in the process of formation, the material must have received an environmental signal that reflects a change in climate and that can be deciphered by modern physical or chemical means. Third, at least some of the material must have retained the signal unaffected by subsequent changes in the environment. Fourth, it must be possible to determine the time at which the inferred climatic conditions held. This last criterion is more easily met in dating marine sediments, because dating of only a small number of layers in a marine sequence allows the age of other layers to be estimated fairly reliably by extrapolation and interpolation. By contrast, because sedimentation is much less continuous in continental regions, estimating the age of a continental bed from the known ages of beds above and below is more risky.

One very old method used in the investigation of past climatic conditions involves the measurement of water levels in ancient lakes. In temperate regions, there are enough lakes for correlations between them to give us a tenable picture. In arid and semiarid regions, on the other hand, the small number of lakes and the great distances between them reduce the possibilities for correlation. Moreover, since lake levels are controlled by rates of evaporation as well as by precipitation, the interpretation of such levels is ambiguous. For instance, the fact that lake levels in the semiarid southwestern United States appear to have been higher during the last ice age than they are now was at one time attributed to increased precipitation. On the basis of snowline elevations, however, it has been concluded that the climate then was not necessarily wetter than it is now, but rather that both summers and winters were cooler, resulting in reduced evaporation

Another problematic method is to reconstruct former climates on the basis of pollen profiles. The type of vegetation in a specific region is determined by identifying and counting the various pollen grains found there. Although the relationship between vegetation and climate is not as direct as the relationship between climate and lake levels, the method often works well in the temperate zones. In arid and semiarid regions in which there is not much vegetation, however, small changes in one or a few plant types can change the picture traumatically, making accurate correlations between neighboring areas difficult to obtain.

8. Which of the following statements about the difference between marine

andcontinental sedimentation is supportedby information in the passage?

A. Data provided by dating marine sedimentation is more consistent with

researchers’ findings in other disciplines than is data provided by dating continental sedimentation.

B. It is easier to estimate the age of a layer in a sequence of continental

sedimentation than it is to estimate the age of a layer in a sequence of marine sedimentation.

C. Marine sedimentation is much less widespread than continental sedimentation D. Marine sedimentation is much more continuous than is continental

sedimentation.

9. Which of the following statements best describes the organization of the passage as a whole?

A. The author describes a method for determining past climatic conditions and

then offers specific examples of situations in which it has been used.

B. The author discusses the method of dating marine and continental sequences

and then explains how dating is more difficult with lake levels than with pollen profiles.

C. The author describes the common requirements of methods for determining

past climatic conditions and then discusses examples of such methods.

D. The author describes various ways of choosing a material for determining past

climatic conditions and then discusses how two such methods have yielded contradictory data.

10. It can be inferred from the passage that paleoclimatologists have concluded

which of the following on the basis of their study of snow-line elevations in the southwest6ern United States?

A. There is usually more precipitation during an ice age because of increased

amounts of evaporation

B. There was less precipitation during the last ice age than there is today.

C. Lake levels in the semiarid southwestern United States were lower during the

last ice age than they are today.

D. The high lake levels during the last ice age may have been a result of less

evapo9ration rather than more precipitation.

11. Which of the following would be the most likely topic for a paragraph that logically

continues the passage?

A. The kinds of plants normally found in arid regions.

B. The effect of variation in lake levels on pollen distribution.

C. The material best suited to preserving signal of climatic changes. D. A third method fro investigating past climatic conditions.

12. the author discusses lake levels in the southwestern United States in order to

A. illustrate the mechanics of the relationship between lake level, evaporation,

and precipitation

B. provide an example of the uncertainty involved in interpreting lake levels.

C. Prove that there are not enough ancient lakes with which to make accurate

correlations