The answer you are looking for is pangea
Answer:
The core is made of two layers: the outer core, which borders the mantle, and the inner core. The boundary separating these regions is called the Bullen discontinuity. The outer core, about 2,200 kilometers (1,367 miles) thick, is mostly composed of liquid iron and nickel.
The Westwards expansion meant that the United States acquired more lands. This meant that the demand for civilians (farmers) increased in order to be able to maintain these lands without the vast interference of the military.
As a result of this, huge amounts of people , especially Europeans , immigrated there in the second half of the 19th century.
The resources of the US increased, both agricultural products as well as gold, timber and silver as a result of this.
However, this aggravated the divide between north and south, leading to an acceleration in the onset of the Civil War.
