One of the most important roles of the rainforest is moderate destructive drought and rain cycles in local areas.
Answer:
plate boundaries
Explanation:
Volcanoes and earthquakes are most likely to form along plate boundaries.
Earthquakes:
An earthquake is generated when two plates move relative to each other. The earthquake itself, is the movement felt on the surface caused by the movement of the tectonic plates at their boundaries. There are a few different types of plate boundaries, NOAA does a great job giving a brief description of each here:
http://oceanexplorer.noaa.gov/facts/plate-boundaries.html
Westward expansion meant that the US acquired ever increasing amounts of land, and needed people, farmers, to settle there so it could maintained without a huge military presence
Liberia.
It comes from the Latin word liber which means free and Liberia is a country in West Africa.