If People Were Dolphins, the Planet Would Be Called “Ocean” - Don't Know Much About Geography - page 77

Lake Michigan is the third-largest of the Great Lakes and the only one completely within the United
States. It is bounded by the states of Michigan, Illinois, Wisconsin, and Indiana. (If for some reason you
want to remember the names of all of the Great Lakes in size order, just think of SHMEO—Superior, Hur-
on, Michigan, Erie, Ontario).
Lake Tanganyika is a deep lake in east-central Africa, bordered predominantly by the countries of
Tanzania and Zaire. The first Europeans to reach it were the explorers Sir Richard Burton and John Speke
in 1858 as they sought the source of the Nile. Stanley and Livingstone had their famous meeting near its
shores in 1871.
Lake Baikal (Ozero Baykal) , located in Siberia, is the world's deepest lake, containing more water
than all five of the Great Lakes of North America put together. Tradition holds that Genghis Khan, the
famed Mongol emperor, was born near the shores of Baikal.
Great Bear Lake , on the Arctic Circle in Canada's Northwest Territories, is frozen for all but four
months of the year.
Lake Malawi (Nyasa Lake) , situated in the southern section of Africa's Great Rift Valley in the coun-
tries of Malawi and Mozambique, is also known as Calendar Lake because it is 365 miles long and 52
miles across at its widest point.
Great Slave Lake , like Great Bear, is in Canada's Northwest Territories and the capital of the province,
Yellowknife, is located on the lake's north shore.
Where Does All the Water Go at Low Tide?
This is one of those childish “Why is the sky blue?” sort of questions to which the answer is not as simple
as it seems. The obvious answer isn't necessarily the correct one. Many people probably think that if it is
high tide on one side of the ocean—say, the western side of the Atlantic—then it must be low tide on the
eastern side of the Atlantic. It isn't that simple. The sea doesn't just slosh back and forth between the two
sides of the ocean like water in a barrel that's being rocked back and forth.
Tides are the regular rise and fall of coastal water levels, caused by gravity—stimulated by the attrac-
tion of the moon and, to a lesser degree, the sun. The moon, 250,000 miles from the earth, is the major
influence on the regular ebb and flow of the earth's tides. Even though the sun is vastly larger than the
moon (the sun has 27 million times the mass of the Moon), its much greater distance from the earth weak-
ens its impact on the earth's tides.
In simple terms, the oceans on the side of the earth facing the moon are “pulled” toward the moon,
causing a bulge or high tide. At the same time, the oceans on the opposite side of the earth—facing away
from the moon—also bulge in the exactly opposite direction, the result of centrifugal force. These two
bulges produce high tides on opposite sides of the earth as water is drawn away. At the same time, there
are compensating low tides halfway between the two bulges. As the moon orbits the earth (in the same dir-
ection the earth is spinning), these bulges literally “travel” around the earth. One way to picture this is as
a rubber band. As you pull two ends of a rubber band, the ends stretch away from each other—that would
be high tide. In between, the rubber is stretched thin, that's low tide.