The Earth's mantle is very important. It is important for the Earth's crust evolution, as well as being the provider of thermal and mechanical forces for plate tectonics. The mantle is what covers the most part of Earth inside if it is not there, then the heat of the core will burn the Earth's crust. And the mantle does make up 84% of Earth's volume, so that wouldn't be good!
The answer to your question is knowledge. Scientific knowledge is the information gathered by the systematic study of nature.
true. google says that it was general John Burgoyne that was defeated.