How could shifts in the physical environment have caused major changes in early civilizations (select 2)
a) build up of silt could have made rivers less salty increasing the supply of clean water
b) too much or too little rain may have ruined crops creating food shortages
c) long term farming could have improved the quality of soil increasing crop yields
d) earthquakes or eruping volcano's may have destroyed communities

Many scandinavians immigrated to the united states as a result of the homestead act of 1862, which offered land to independent farmers. this is an example of a push factor, because turmoil in scandinavia encouraged people to leave. push factor, because a new opportunity encouraged people to come to the us. pull factor, because turmoil in scandinavia encouraged people to leave. pull factor, because a new opportunity encouraged people to come to the us.

How did the iran-contra affair impact the conflict between the united states and the soviet union? what role did the iran-contra affair play in both iran and nicaragua?

What former head of the cuban secret service was charged with protecting the country's prime minister for nearly 50 years?