Newspaper publishers in the United States have long been enthusiastic users and distributors of weather maps. Although some newspapers that had carried the United States Weather Bureaus national weather map in 1912 dropped it once the novel...
In eighteenth-century colonial America, flowers and fruit were typically the province of the botanical artist interested in scientific illustration rather than being the subjects of fine art. Early in the nineteenth century, however, the Pe...
Scientists have discovered that for the last 160,000 years, at least, there has been a consistent relationship between the amount of carbon dioxide in the air and the average temperature of the planet. The importance of carbon dioxide in re...
It is estimated that over 99 percent of all species that ever existed have become extinct. What causes extinction? When a species is no longer adapted to a changed environment, it may perish. The exact causes of a species death vary from si...
The Moon, which has undergone a distinct and complex geological history, presents a striking appearance. The moon may be divided into two major terrains: the maria (dark lowlands) and the terrace( bright highlands). The contrast in the refl...
Some animal behaviorists argue that certain animals can remember past events, anticipate future ones, make plans and choices, and coordinate activities within a group. These scientists, however, are cautious about the extent to which animal...
The first birds appeared during late Jurassic times. These birds are known from four very good skeletons, two incomplete skeletons, and an isolated feather, all from the Solnhofen limestone of Bavaria, Germany. This fine-grained rock, which...
Question 10-19 Geographers say that what defines a place are four properties: soil, climate, altitude, and aspect, or attitude to the Sun. Floridas ancient scrub demonstrates this principle. Its soil is pure silica, so barren it supports on...
Newspaper publishers in the United States have long been enthusiastic users and distributors of weather maps. Although some newspapers that had carried the United States Weather Bureaus national weather map in 1912 dropped it once the novel...
Question 10-19 Geographers say that what defines a place are four properties: soil, climate, altitude, and aspect, or attitude to the Sun. Floridas ancient scrub demonstrates this principle. Its soil is pure silica, so barren it supports on...
Question 30-40 Because the low latitudes of the Earth, the areas near the equator, receive more heat Than the latitudes near the poles, and because the nature of heat is to expand and move, Heat is transported from the tropics to the middle...
Question 20-30 It is estimated that over 99 percent of all species that ever existed have become extinct. What causes extinction? When a species is no longer adapted to a changed environment, it may perish. The exact causes of a species dea...
Questions 21-29 Under the Earths topsoil, at various levels, sometimes under a layer of rock, there are deposits of clay. Look at cuts where highways have been built to see exposed clay beds; or look at a construction site, where pockets of...
Question 41-50 The Moon, which has undergone a distinct and complex geological history, presents a striking appearance. The moon may be divided into two major terrains: the maria (dark lowlands) and the terrace( bright highlands). The contr...
Questions 41-50 The Homestead Act of 1862 gave beads of families or individuals aged twenty-one or older the right to own 160 acres of public land in the western United States after five years of residence and improvement. This law was inte...
Question 1-9 Often enough the craft workers place of employment in ancient Greece was set in rural isolation. Potter, for instance, found it convenient to locate their workshops near their source of clay, regardless of its relation to the c...
Question 1-9 Often enough the craft workers place of employment in ancient Greece was set in rural isolation. Potter, for instance, found it convenient to locate their workshops near their source of clay, regardless of its relation to the c...
Questions 30-40 The smooth operation of an ant colony depends on ten to twenty different signals, most of which are pheromones (chemical signals triggering behavioral responses). It is estimated that red fire ants employ at least twelve dif...
Questions 20-29 Many prehistoric people subsisted as hunters and gatherers. Undoubtedly, game animals, including some very large species, provided major components of human diets. An important controversy centering on the question of human...
Questions 10-20 Long before they can actually speak, babies pay special attention to the speech they hear around them. Within the first month of their lives, babies responses to the sound of the human voice will be different from their resp...
