Engineers most likely chose the isthmus of Panama as the location of the canal because it was one of the shortest land areas that had to be crossed in order to create a route for ships to travel from the Caribbean Sea and the Atlantic to the Pacific Ocean. Panama's isthmus is a unique land feature that is a thin piece of land relatively that allowed for easier development of the canal due to its shorter distance in comparison to much wider parts of Central America.
Answer: the birth of Arabian civilization can be dated to 7th century A.D. Then Islam was spreading westwards to northern Africa...from Egypt to Maroccos. From Maroccos Muslims spread to Iberian peninsula. But they were not able to move more northwards ....beyond Pyrenees. Christian states were stable, well-organized and were able to organize their armies and protect themselves.
Explanation: they were not able to move beyond Pyrenees because already in the north of Iberian peninsula there were well-organized Christian kingdom. They were small but they constituted a barrier. The only significan Arabian invasion to Europe consitutes "battle of Poitiers" (sometimes called "battle of Tours) in 732 A.D. There Franks led by Charles Martel were victorious and Arabians had to retreat behind Pyrenees. Later on Arabians were expulsed from Iberian peninsula (first from Portugal, then from Spain).
Sunlight is type of EM wave. The intensity of EM follows inverse square law.
This means that the intensity at a distance that is n times greater will be n^2 times smaller.
Now we set this equation to be equal to 9 and we solve it for n:
The intensity is 9 times greater at a distance that is equal to a 1/3 of Earth's distance:
D. crust and upper mantle
because it is the two uppermost layers that moves the plates to create earthquakes, landslides, etc.
A is wrong because there is another layer in between the two called the upper mantle.
B and C is wrong because they do not contain the crust, the outermost layer of the earth.
