Discuss the input and outflow of sand in a coastal cell. What will be an ideal response?
Rivers bring in most new sand on a coast. The sand is moved parallel to the beach by
longshore drift, and it is moved onshore and offshore at right angles to the beach as the
seasons change. If a beach is stable in size, neither growing nor shrinking, the amount of new
sand entering must be balanced by the amount of old sand being removed. Sand that drifts
below the reach of wave action is lost from the coast and may migrate farther out on the
continental shelf. Some sand is driven by longshore currents into the nearshore heads of
submarine canyons. Sand moving away from shore in these canyons sometimes forms
impressive sandfalls and is lost from the beaches above. The bulk of this material is
transported by gravity down the axis of the canyon and ultimately deposited on a submarine
fan at the base of the slope. The natural sector of a coastline in which sand input and sand
outflow are balanced may be thought of as a coastal cell. Coastal cells are usually bounded by submarine canyons that conduct sediments to the deep sea. Their size varies greatly. They
are often very large along the relatively smooth, tectonically passive trailing edges of
continents; coastal cells along the southeastern coast of the United States, for example, are
hundreds of kilometers long.
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The main reason that surface water pollution has largely decreased in the United States since 1950 is
A. The Clean Water Act B. The discovery of newer technology that makes it cheaper not to pollute C. The decrease in water withdrawal for industrial uses D. A series of epidemics that inspired action E. The emphasis, in 1950, on watershed management
Given the colonial history of each continent, which characteristic distinguishes religion in South America from North America?
A) having a Roman Catholic majority B) having a Protestant majority C) location relative to the Equator D) Ethnic religions make up the majority in one but not the other. E) Latin America has more Protestants, Jews, and Muslims.
Tiny plants and animals that float freely with ocean currents are termed _______________
Fill in the blank(s) with correct word
What is the fertility rate in the U.S.?
A) 2.5 B) 1.8 C) 1 D) 2.1 E) 2.3