There are main cataracts, or waterfalls, along the nile river. a. 4 b. 92 c. 2 d. 5

The six cataracts of the Nile River are shallow stretches where boulders break up the water like white water rapids. Counting from north to south, the first is located in Egypt, and the rest are located in Sudan. In geography, a cataract is defined as a large waterfall or rapids.

The cataracts are sections where the river tumbles over rocks and have long kept boats from going up and down the river from Equatorial Africa to Egypt. There are six classical cataracts, but there are really many more.

a

explanation:

the captain of a steam ship naturally chooses the shortest route to his destination. since a sailing ship is usually pushed by winds and currents, its captain must find a route where the wind will probably blow in the right direction. tacking, i.e. using contrary wind to pull (sic) the sails, was always possible but wasted time because of the zigzagging required, and this would significantly delay long voyages. the early european explorers were not only looking for new lands. they also had to discover the pattern of winds and currents that would carry them where they wanted to go. during the age of sail winds and currents determined trade routes and therefore influenced european imperialism and modern political geography. for an outline to the main wind systems see global wind patterns.

pilotage or cabotage, in one sense, is the art of sailing along the coast using known landmarks. navigation, in one sense, is the art of sailing long distances out of sight of land.[1] although the polynesians were able to sail the pacific (with great difficulty) and people regularly sailed north and south across the mediterranean, before the time of columbus nearly all sailing was coastal pilotage

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