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Climates and Farming in America
Keywords: climate, North America, region, soil, fertilization
The wide variety of climates in North America has helped spawn a complex pattern of soil regions. In general, the realm's soils also reflect the broad environmental partitioning into "humid America" and "arid America." Where annual precipitation exceeds 20 inches(50 centimeters),soils in humid areas tend to be acidic in chemical content, since crops do best in soils that are neither acidic(higher in acid content) nor alkaline(higher in salt content). Fertilization is necessary to achieve the desired level of neutrality between the two. Arid America's soils are typically alkaline and must be fertilized back toward neutrality by adding acidic compounds. Although many of these dryland soils, particularly in the Great Plains, are quite fertile, European settlers learned over a century ago that water is the main missing ingredient in achieving their agricultural potential. In the 1970's, certain irrigation methods were perfected and finally provided a real opportunity to expand more intensive farming west from the Central Lowland into the drier portions of the Great Plains. Glaciation also enhanced the rich legacy of fertile soils in the central United States, both from the deposition of mineral-rich glacial debris left by meltwater and from thick layers of fine wind-blown glacial material, called loess, in and around the middle Mississippi Valley.
Natural vegetation patterns could be displayed on a map of North America, but theenormous human modification of the North American environment in modern times hasall but reduced this regionalization scheme to the level of the hypothetical. Nonetheless,the humid America-arid America dichotomy is still a valid generalization: the natural vegetation of areas receiving more than 20 inches of water yearly is forest, whereas the drier climates give rise to a grassland cover. The forests of North America tent to make a broad transition by latitude. In the Canadian North, needle-leaf forests dominate, but these coniferous trees become mixed with broadleaf deciduous trees as one crosses the border into the Northeast United States. As one proceeds toward the Southeast, broadleaf vegetation becomes dominant. Arid America mostly consists of short-grass prairies or stepper. The only areas of true desert are in the Southwest.
22. According to the passage, the inventors of written language in Mesopotamia were probably the
(A) Babylonians
(B) Subarians
(C) Akkadians
(D) Sumerians
23. The word "subjugated" in line 4 is closest in meaning to
(A) distinguished
(B) segregated
(C) concentrated
(D) conquered
24. The phrase "synonymous with " in line 5 is closest in meaning to
(A) equivalent to
(B) important for
(C) respected in
(D) familiar with
25. According to the passage, by the year 3000 B.C., the Sumerians had already done all of the following EXCEPT:
(A) They had abandoned the area north of the Persian Gulf.
(B) They had established themselves in cities.
(C) They had started to communicate through written language.
(D) They had created bronze tools and weapons.
26. The word "Some" in line 14 refers to
(A) Archaeologists
(B) Sumerians
(C) years
(D) clay tablets
27. Which of the following can be inferred from the passage concerning the Sumerians?
(A) They were descendants of the Persians.
(B) They were the first people to cultivate the valley of the Tigris.
(C) They were accomplished musicians.
(D) They had the beginnings of an economy.
28. According to the passage, when did archaeologists began to be able to understand tablets inscribed in Sumerian?
(A) In the early nineteenth century
(B) More than 150 years ago
(C) After the 1890's
(D) In the mid-eighteenth century
29. According to the passage, in what way did the Sumerian language resemble ancient Greek and Latin?
(A) It was invented in Mesopotamia.
(B) It became well established around 3000 B.C.
(C) It became a classical language.
(D) It was used exclusively for business transactions.
30. The word "excavating" in line 19 is closest in meaning to
(A) living
(B) digging
(C) assembling
(D) building
31. According to the passage, how did archaeologists learn to read the Sumerian language?
(A) By translating the work of the Subarians
(B) By using their knowledge of spoken Semitic languages
(C) By comparing Sumerian to other classical languages
(D) By using their knowledge of Akkadian
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