Which is one theory about what caused the decline of the indus valley civilization? a. earthquakes in the himalayas caused massive destruction. b. diseased animals created food shortages for the people. c. the soil became too salty for crops to grow. d. merchants and traders stopped coming into the valley..

The correct answer is C) The soil became too salty for crops to grow.

One theory about what caused the decline of the Indus Valley civilization is "The soil became too salty for crops to grow."

Another important cause, according to scientists and archeologists, could have been a great flood that wiped the entire civilization. Let's have in mind that the Indus Valley Civilization settled in next to the Indus River. Other ancient civilizations also settled in next to important rivers because of the many benefits it generated to them That was the case of the ancient Egypt civilization that settled in next to the Nile River banks and the Sumerian civilization that settled in between the Tigris and Euphrates Rivers.

answer:   migrations were important in the neolithic period. "two major migrations passing through southeastern europe were confirmed by the means of archaeo-genetic studies."

the first migration was the early neolithic period -- 6,000 before common era (bce) -- when the first farmers, from anatolia -- asia minor -- spread through europe. the second migration occurred during the early bronze age (3,000-2,500 bce) when the so-called "steppe population," from the eurasian steppe, replaced much of northern europe's previous population.

the first farmers of northern and western europe passed through southeastern europe with limited hunter-gatherer genetic admixture, which occurs when two or more previously isolated populations begin interbreeding. however, some groups that remained mixed extensively -- without the male-biased, hunter-gatherer admixture that prevailed later in the north and west, according to latest discoveries. southeastern europe continued to be a nexus between east and west, with intermittent genetic contact with the steppe people up to 2,000 years before the migrations that replaced much of northern europe's population.

"in some places, hunter-gatherers and incoming farmers seem to have mixed very quickly," says iain mathieson, a geneticist at the university of pennsylvania, who was first author of the paper. "but, mostly, the two groups remained isolated, at least for the first few hundred years. these hunter-gatherers had been living there for thousands of years, and it must have been quite a shock to have these new people show up -- with a completely different lifestyle and appearance."

the correct answer is "pioneers carried all of their possessions on long and dangerous trails".

the first wave of pioneers travelled in 1842. they were merely 100 people. the next year that sum climbed to 1000 men, women, and children. these people travelled around 2,000 miles to oregon in the hopes of a better life. although the first part of the trip didn't present many obstacles, as time and miles went by they learnt that threat came from simple things, like becoming ill due to unclean water or bad food.

the weather didn't much, as wagons couldn't protect them from storms. as they travelled through the desert, the intense heat caused wood to shrink. their own lips abscessed and split because of the dry air. the only cure for this was to rub axle grease on their lips.

even crossing rivers was dangerous. sometimes wheels were damaged by unseen rocks on shallow water. mud didn't much either. pioneers were afraid of indian attacks, but there aren't many records of fights between pioneers and native americans. accidents happened because of negligence, exhaustion, guns, and bad weather.

history says that 1 of 10 pioneers who travelled to oregon didn't survive the journey. diseases spread fastly because they didn't have doctors and medical care was ofently improvised. one of the most deadly diseases they came upon was cholera, which became a worldwide pandemia.