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The Grand Canyon in north-western______is one of natures most impressive sights.
A．Utah
B．Arizona
C．Nevada
D．Idaho
答案
更多“The Grand Canyon in north-western______is one of natures most impressive sights.A．UtahB．Ar”相关的问题
第1题
A．Utah
B．Arizona
C．Nevada
D．Oregon
第2题
A．Y
B．N
C．NG
第3题
A．10 100.
B．277.
C．14
D．10
第4题
It can be concluded from this passage about the Grand Canyon that ______.
A．its shapes are constantly changing
B．it contains approximately 14 million tons of rock
C．its eruptions have increased in recent years
D．it is being eroded by toxic waste and pollutants
第5题
Where does the desert plant agave grow in the Grand Canyon？
A．It grows on the towering buttes.
B．It grows on the mesas.
C．It grows on the plateau.
D．It grows in the depths of the valley.
第6题
A. While the
B. The
C. For the
D. Because of the
第7题
The Grand Canyon carved by______is one of natures most important sights.
A．the Columbia River
B．the Colorado River
C．the Rio Grande River
D．the Missouri River
第8题
Which of the following conclusions about the Grand Canyon can be drawn from the passage？
A．Its contours are constantly changing.
B．It contains approximately 14 million tons of rock.
C．Its eruptions have increased in recent years.
D．It is being eroded by toxic waste and pollutants.
第9题
Standing on the rim of the Grand Canyon(大峡谷), gazing across this giant would in the Earth's surface, a visitor might assume that the canyon had been caused by some ancient convulsing (震动). In fact, the events that produced the canyon, far from being sudden and catastrophic, simply add up to the slow and orderly process of erosion.
Many millions of years ago, the Colorado Plateau in the Grand Canyon area contained 1000 more feet of rock than it does today and was relatively level. The additional material consisted of some 14 layered formations of rock. In the Grand Canyon region these layers were largely worn away over the course of millions of years.
Approximately 65 million years ago the plateau's flat surface in the Grand Canyon area bulged upward from internal pressure, geologists refer to this bulging actions upwading(弯曲上升); it was followed by a general elevation of the whole Colorado Plateau, a process that is still going on. As the plateau gradually rose, shallow rivers that winded across it began to run more swiftly and cut more definite courses. One of these rivers, located east of the up- ward, was the ancestor of the Colorado. Another river system, called the Hualapai, flowing west of the upward, extended itself eastward by cutting back into the upward, it eventually connected with the ancient Colorado and captured its waters. The new river then began to carve out the 277-mile-long trench that eventually became the Grand Canyon. Geologists estimate that this initial cutting action began no earlier than 10 million years ago.
Since then, the Canyon forming has been cumulative. To the corrosive force of the river itself have been added other factors. Heat and cold, rain and snow, along with the varying resistance of the rocks, increase the opportunities for erosions, the Canyon walls crumble, the river acquires a cutting tool. Tons of debris, rainfall running off the high plateau creates feeder streams that carve side canyons. Pushing slowly backward into the. plateau, the side canyons expose new rocks, and the pattern of erosion continues.
The passage mainly discusses______.
A．patterns of erosion in different mountain ranges
B．forces that made the Grand Canyon
C．the increasing pollution of the Colorado River
D．the sudden appearance of the Grand Canyon
第10题
What does the author mean by saying that the Grand Canyon is of relatively recent origin？
A．The river almost completed its work of erosion only about six million years ago.
B．The Colorado Plateau only rose a comparatively short time from now.
C．Volcanic debris and intrusions of igneous rock are of recent origin.
D．The form. of the canyon is the result of the recent work done by the natural force.
