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Posted 2023-02-28 we1less

Chemical and Biological Weathering of Rocks

Paragraph 2
The minerals that rocks are made of are subject to alteration by chemical weathering. Some minerals, such as quartz, resist this alteration quite successfully, but others, such as the calcium carbonate of limestone, dissolve easily. In any rock made up of a combination of minerals, the chemical breakdown of one set of mineral grains leads to the disintegration of the whole mass. In granite (made chiefly of the minerals quartz and feldspar), the quartz resists chemical decay much more effectively than does the feldspar, which is chemically more reactive and weathers to become clay. Often granite surfaces are heavily pitted (marked with many small holes or depressions). In such cases, the feldspar grains are likely to have been weathered to clay and blown or washed away. The quartz grains still remain, but they may eventually be loosened too. So even a rock as hard as granite cannot withstand the weathering process forever.

1. What is the author’s purpose in discussing quartz and limestone? 
A. To explain why quartz is more common than limestone

        1. 没说更普遍

B. To point out that most rocks are made up of a combination of minerals

        1. 没说组成

C. To illustrate that some minerals are more affected by chemical weathering than others are

D. To show that chemical weathering can occur only in the calcium-carbonate form of a mineral

        1. only原文没提

        S：purpose 目的题

        D：quartz and limestone

        S：

        G：

2.The word “withstand” in the passage is closest in meaning to 
A. continue
B. avoid
C. experience
D. resist

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Paragraph 3
Three kinds of mineral alteration dominate in chemical weather: hydrolysis, oxidation, and carbonation. When minerals are moistened, hydrolysis occurs, producing not only a chemical alteration but expansion in volume as well. This expansion can contribute to the breakdown of rocks. Hydrolysis, it should be noted, is not simply a matter of moistening; it is a true chemical 
alteration, and minerals are transformed into other mineral compounds in the process. For example, feldspar hydrolysis yields a clay mineral (silica) in solution (that is, dissolved in water), and a carbonate or bicarbonate of potassium, sodium, or calcium in solution. The new minerals tend to be softer and weaker than their predecessors. In granite boulders, hydrolysis combines with other processes to cause the outer shells to flake off.

3. According to paragraph 3, which of the following statements is true about the effect of feldspar hydrolysis on a rock?

A. It produces solutions of clay and other minerals.

B. It strengthens the minerals involved in the chemical alteration.

C. It moistens the rock but does not change the rock’s mineralcompounds.

D. It expands the rock without causing the rock to break apart.

        S：true 细节题 effect 问影响

        D：feldspar hydrolysis - n.水解;

        S：

        G：

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Paragraph 4
When minerals in rocks react with oxygen in the air, the chemical process is known as oxidation. We have plenty of evidence of this process in the reddish color of soils in many parts of the world and in the reddish brown hue of layers exposed in such places as the Grand Canyon. The products of oxidation are compounds of iron and aluminum, which account for the reddish 
colors seen in so many rocks and soils. In tropical areas, oxidation is the dominant chemical-weathering process.

4. Paragraph 4 implies that rocks found in tropical areas

A. do not weather as much as rocks found in colder climates

B. contain only small amounts of iron and aluminum

C. are commonly reddish brown        commonly  adv. 通常地; 一般地; 平凡地; 粗俗地;

D. rarely react with the oxygen in the air

定位词不多可以用选项定位

推理题：infer  implies  suggest  support  conclude

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Paragraph 5
Various circumstances may convert water into a mild acid solution, thereby increasing its effectiveness as a weathering agent. With a small amount of carbon dioxide, for instance, water forms carbonic acid, which in turn reacts with carbonate minerals such as limestone and dolomite (a harder relative of limestone). This form of chemical weathering, carbonation, is especially vigorous in humid areas, where limestone and dolomite formations are often deeply pitted and grooved, and where the evidence of solution and decay is prominent. This process even attacks limestone underground, contributing to the formation of caves and subterranean corridors. In arid areas, however, limestone and dolomite resist weathering much better, although they may show some evidence of carbonation at the surface.

Various  adj. 各种各样的; 千差万别的;

thereby  adv. 从而

agent  n. 代理人/商（化学）剂

5.The word “prominent” in the passage is closest in meaning to 
A. extensive
B. present 
C. complex 
D. recent

6. According to paragraph 5, all of the following statements are true of carbonation EXCEPT:

A. It has less of an effect on rocks in dry areas than it does on rocks in wet areas.

B. It is responsible for the formation of caves and underground corridors.

C. It rarely affects harder rocks such as limestone and dolomite.

        原文没说，坚硬的 limestone dolomite，几乎不反应

D. It involves a reaction between carbonic acid and carbonate minerals.

        involve v. 包含，涉及; （使）加入; 表明…

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Paragraph 6
Biological weathering is the breakdown of rock caused by the actions of living organisms. This kind of weathering plays an important role in the formation of soils. It is through the breakdown of rocks and the accumulation of a layer of minerals that plants can grow — plants whose roots and other parts, in turn, contribute to the weathering processes. But it is likely that the role of plant
roots in weathering is somewhat overestimated. The roots follow paths of least resistance and adapt to every small irregularity in the rock. Roots certainly keep cracks open once they have been formed. More importantly, however, areas of roots tend to collect decaying organic material that is involved in chemical-weathering processes.

7. According to paragraph 6, what does the author believe about the role of plant roots in weathering?

A.Rocks that contain plant roots weather more slowly than rocks that donot.

B.Weathering helps plants to grow, but plant roots probably do not play a role in weathering.

C.Plant roots contribute to biological weathering but not to chemical weathering.

D.Plant roots do contribute to weathering, although not as much as some have suggested.

细节题

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Paragraph 7
■ One of the most important aspects of biological weathering is the mixing of soil by burrowing animals and worms. ■ Another interesting aspect is the action of lichens, a combination of algae and fungi that live on bare rock. ■Lichens draw minerals from the rock through an absorption process. ■ The swelling and contraction of lichens as they alternately get wet and dry may
also cause small particles of rock to fall off.

8. According to paragraph 7, living organisms contribute to weathering in all of the following ways EXCEPT:

A. by mixing soil

B. by drawing minerals from rocks

        drawing n. 素描（画）v. 画; 移动; 拉，拖; 拔出

C. by causing small pieces of rock to fall off 

D. by moistening rocks until they expand

        expand v. 扩大; 发展; 详细阐明;

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9. Look at the four squares [■] that indicate where the following sentence could be added to the passage.

The result of this removal of minerals is a very gradual eating away of rock surfaces.

定位：

位置：this 放后

■ One of the most important aspects of biological weathering is the mixing of 
soil by burrowing animals and worms. ■ Another interesting aspect is the 
action of lichens, a combination of algae and fungi that live on bare rock. ■
Lichens draw minerals from the rock through an absorption process. ■ The 
swelling and contraction of lichens as they alternately get wet and dry may
also cause small particles of rock to fall off.

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10. Prose Summary
Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some answer choices do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.

Chemical and biological weathering are responsible for the chemical alternation and physical disintegration of rocks.

A. Of the three types of chemical weathering, carbonation causes the greatest amount of chemical alteration in rocks, while hydrolysis causes the least.

B. All rocks are subject to chemical weathering, but the rate at which this weathering occurs depends on the mineral composition of the rock.

C. Oxidation normally results in the creation of new mineral in a rock that are softer and weather than the original minerals.

D. The availability of oxygen, carbon dioxide, and water has a significant impact on the type of chemical weathering that a rock is most likely to experience.

E. Lichens are an especially effective weathering agent because they contribute to both the chemical and biological weathering of rocks.

F. Plant growth and the actions of living organisms both contribute to the biological weathering of rocks.

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The origins of plant and animal domestication
The transition to gardens, fields, and pastures was probably gradual, the natural outgrowth of a long familiarity with the environmental requirements, growth cycles, and reproductive mechanisms of whatever plants and animals humans liked to eat, ride, or wear.

4. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.

A The change to land cultivation was a slow process because humans were familiar with the needs of relatively few plants and animals.

        1. 原文说无论什么植物动物

B The cultivation of land occurred gradually as it was the product of extensive human experience observing plants and animals of value tohumans.

C Gardens, fields, and pastures were outgrowths of the desire for plants and animals that humans knew from long familiarity were good to eat, wear, orride.

        1. 不存在主语

D People learned about environmental requirements, growth cycles, and reproductive mechanisms through their long familiarity with plants and animals that they liked to eat, ride, and wear.

        1. 不存在主语

句子简化题分析

1. 找主干

2. 找逻辑词

3. 考点