Continents and ocean basins represe

Continents and ocean basins represent the largest identifiable bodies on Earth. On the solid portions of the planet, the second most prominent features are flat plains, elevated plateaus, and large mountain ranges. In geography, the term “continent” refers to the surface of continuous landmasses that together comprise about 29.2% of the planet’s surface. On the other hand, another definition is prevalent in the general use of the term that deals with extensive mainlands, such as Europe or Asia, that actually represent one very large landmass. Although all continents are bounded by water bodies or high mountain ranges, isolated mainlands, such as Greenland and India-Pakistan areas are called subcontinents. In some circles, the distinction between continents and large islands lies almost exclusively in the size of particular landmass.
The analysis of compression and tension in the earth’s crust has determined that continental structures are composed of layers that underlie continental shelves. A great deal of disagreement among geologists surrounds the issue of exactly how many layers underlie each landmass because of their distinctive mineral and chemical composition. It is also quite possible that the ocean floor rests on the top of unknown continents that have not yet been explored. The continental crust is believed to have been formed by means of a chemical reaction when lighter materials separated from heavier ones, thus settling at various levels within the crust. Assisted by the measurements of the specifics within crust formations by means of monitoring earthquakes, geologists can speculate that a chemical split occurred to form the atmosphere, sea water, and the crust before it solidified many centuries ago.
Although each continent has its special features, all consist of various combinations of components that include shields, mountain belts, intracratonic basins, margins, volcanic plateaus, and blockvaulted belts. The basic differences among continents lie in the proportion and the composition of these features relative to the continent size. Climatic zones have a crucial effect on the weathering and formation of the surface features, soil erosion, soil deposition, land formation, vegetation, and human activities.
Mountain belts are elongated narrow zones that have a characteristic folded sedimentary organization of layers. They are typically produced during substantial crustal movements, which generate faulting and mountain building. When continental margins collide, the rise of a marginal edge leads to the formation of large mountain ranges, as explained by the plate tectonic theory. This process also accounts for the occurrence of mountain belts in ocean basins and produces evidence for the ongoing continental plate evolution.

60. What does this passage mainly discuss?
A. Continental drift and division B. Various definitions of the term “continent”
C. Continental structure and crust D. Scientific analyses of continental crusts
61. According to the passage, how do scientists define continents?
A. As masses of land without divisions B. As extensive bodies of land
C. As the largest identifiable features D. As surgical compositions and ranges
62. In line 6, the word “bounded” is closest in meaning to ___________.
A. covered B. convened C. delimited D. dominated
63. The author of the passage implies that the disagreement among scientists is based on the fact that
A. each continent has several planes and shelves
B. continents have various underlying layers of crust
C. continents undergo compression and experience tension
D. continents have different chemical makeup
64. The word “specifics” in line 16 is closest in meaning to
A. specialities B. speculations C. exact details D. precise movements
65. The word “it” in line 18 refers to
A. a chemical split B. the crust C. the atmosphere D. sea water
66. The author of the passage implies that ___________.
A. it is not known exactly how the continental crust was formed
B. geologists have neglected the exploration of the ocean floor
C. scientists have concentrated on monitoring earthquakes
D. the earth’s atmosphere split into water and solids
67. According to the passage, what are the differences in the structure of continents?
A. The proportional size of continents to one another
B. Ratios of major components and their comparative size
C. The distinctive features of their elements
D. Climatic zones and their effect on the surface features
68. In line 28, the phrase “This process” refers to ___________.
A. continental collision B. mountain ranges C. the rise of margins D. plate tectonic theory
69. The author of the passage implies that ___________.
A. the process of mountain formation has not been accounted for
B. mountain ranges on the ocean floor lead to surface mountain building
C. faulting and continental margins are parts of plate edges
D. the process of continent formation has not been completed
70. The word “evidence” in the last line is closest in meaning to ___________.
A. eventually B. confirmation C. exemplification D. challenge