Listen carefully, understand, and answer the questions.
Lesson : can the salt damage rocks?
In Death Valley, California, one of the hottest, most arid places in North America, there is much salt, and salt can damage rocks impressively. Inhabitants of areas elsewhere, where streets and highways are salted to control ice, are familiar with the resulting rust and Line deterioration on cars. That attests to the chemically corrosive nature of salt, but it is not the way salt destroys rocks. Salt breaks rocks apart principally by a process called crystal prying and wedging. This happens not by soaking the rocks in salt water, but by moistening their bottoms with salt water. Such conditions exist in many areas along the eastern edge of central Death Valley. There, salty water rises from the groundwater table by capillary action through tiny spaces in sediment until it reaches the surface. Most stones have capillary passages that suck salt water from the wet ground. Death Valley provides an ultra-dry atmosphere and high daily temperatures, which promote evaporation and the formation of salt crystals along the cracks or other openings within stones. These crystals grow as long as salt water is available. Like tree roots breaking up a sidewalk, the growing crystals exert pressure on the rock and eventually pry the rock apart along planes of weakness, such as banding in metamorphic rocks, bedding in sedimentary rocks, or preexisting or incipient fractions, and along boundaries between individual mineral crystals or grains. Besides crystal growth, the expansion of halite crystals (the same as everyday table salt) by heating and of sulfates and similar salts by hydration can contribute additional stresses. A rock durable enough to have withstood natural conditions for a very long time in other areas could probably be shattered into small pieces by salt weathering within a few generations. The dominant salt in Death Valley is halite, or sodium chloride, but other salts, mostly carbonates and sulfates, also cause prying and wedging, as does ordinary ice. Weathering by a variety salts, though often subtle, is a worldwide phenomenon. Not restricted to arid regions, intense salt weathering occurs mostly in salt-rich places like the seashore, near the large saline lakes in the Dry Valleys of Antarctica, and in desert sections of Australia, New Zealand, and central Asia.
Di Death Valley (lembah kematian), California, merupakan salah satu tempat terpanas dan terkering di Amerika Utara, yang terdapat banyak garam. Garam dapat melapukkan bebatuan secara mengesankan. Penduduk di daerah lain mengasinkan jalan kota maupun jalan besar untuk mengendalikan es, meskipun mereka memahami karat dan kerusakan mobil yang diakibatkannya. Hal itu membuktikan sifat kimia korosif garam, tetapi bukan cara garam menghancurkan bebatuan.
Garam memecah batu terutama dengan proses yang disebut pengikisan dan pengikatan Kristal.
Hal ini terjadi bukan dengan merendam batu dalam air garam, tetapi dengan membasahi bagian bawahnya dengan air garam. Kondisi seperti itu terjadi di berbagai daerah di sepanjang tepi timur pusat Lembah Kematian. Di sana, air garam naik dari permukaan air tanah melalui proses kapiler melalui celah kecil di sedimen hingga mencapai permukaan.
Kebanyakan batu memiliki saluran kapiler yang menyedot air garam dari tanah basah. Lembah kematian menyediakan atmosfer yang sangat kering dan suhu harian yang tinggi, yang mendorong penguapan dan pembentukan kristal garam di sepanjang retakan atau celahan lain di dalam batu. Kristal ini tumbuh selama air garam tersedia. Seperti akar pohon yang memecah trotoar, kristal yang tumbuh memberikan tekanan pada batu dan akhirnya membongkar batu di sepanjang bidang yang lapuk, seperti pembentukan garis-garis pada batuan metamorf, lapisan di batuan sedimen, atau fraksi yang sudah ada sebelumnya atau baru jadi, dan di sepanjang batas antara kristal mineral itu sendiri atau biji-bijian. Selain pembentukkan kristal, pemuaian kristal garam batu sama seperti garam dapur sehari-hari) dengan pemanasan dan melalui sulfat dan garam serupa melalui beberapa tahapan dapat memberikan tekanan tambahan. Sebuah batu yang telah cukup bertahan lama secara alami untuk waktu yang sangat lama di daerah lain mungkin bisa hancur berkeping-keping oleh pelapukan garam dalam beberapa generasi. Garam yang dominan di lembah kematian adalah garam batu, atau natrium klorida, tetapi garam lain, dengan kandungan karbonat dan sulfat, juga menyebabkan pengikisan dan pengikatan, seperti halnyaproses es. Pelapukan oleh berbagai garam, meskipun seringkali tidak disadari, adalah fenomena di seluruh dunia. Tidak terbatas pada daerah kering, pelapukan garam yang intens sebagian besar terjadi di tempat-tempat kaya garam seperti pantai, dekat danauk air asin di Lembah Kering Antartika, dan di bagian gurun Australia, Selandia Baru, dan Asia Tengah.
41. What is the passage mainly about?
)A) The destructive effects of salt on rocks.
(B) The impressive salt rocks in Death Valley.
(C) The amount of salt produced in Death Valley.
(D) The damaging effects of salt on roads and highways.
42. The word “it” in line 9 refers to.
(A) salty water.
(B) groundwater Table.
(C) capillary action.
(D) sediment.
43. The word “exert” in line 14 is closest in meaning to.
(A) put.
(B) reduce.
(C) replace.
(D) control.
44. In lines 13-17, why does the author compare tree roots with growing salt crystals?
(A) They both force hard surfaces to crack.
(B) They both grow as long as water is available.
(C) They both react quickly to a rise in temperature.
(D) They both cause salty water to rise from the groundwater table.
45. In lines 17-18, the author mentions the “expansion of halite crystals…by heating and of sulfates and similar salts by hydration” in order to.
(A) present an alternative theory about crystal growth.
(B) explain how some rocks are not affected by salt.
(C) simplify the explanation of crystal prying and wedging.
(D) introduce additional means by which crystals destroy rocks.
46. The word “durable” in line 19 is closest in meaning to.
(A) large.
(B) strong.
(C) flexible.
(D) pressured.
47. The word “shattered” in line 20 is closest in meaning to.
(A) arranged.
(B) dissolved.
(C) broken apart.
(D) gathered together.
48. The word “dominant” in line 22 is closest in meaning to.
(A) most recent.
(B) most common.
(C) least available.
(D) least damaging.
49. According to the passage, which of the following is true about the effects of salts on rocks?
(A) Only two types of salts cause prying and wedging.
(B) Salts usually cause damage only in combination with ice.
(C) A variety of salts in all kinds of environments can cause weathering.
(D) Salt damage at the seashore is more severe than salt damage in Death Valley.
50. Which of the following can be inferred from the passage about rocks that are found in areas where ice is common?
(A) They are protected from weathering.
(B) They do not allow capillary action of water.
(C) They show similar kinds of damage as rocks in Death Valley.
(D) They contain more carbonates than sulfates