I was filling this cloze test from a book (the bolded words are answers):
There are many methods of mining, each of which is based upon where a mineral deposit is found in the earth. While some mineral deposits are far
..., others lie at or near the earth surface. Several different mining methods are used when deposit occur close to the earth's surface.
Here are the choices for the blank:
I chose underground as the answer because it seems very logical and I don't suppose it will cause a grammatical error; however, the book says the correct answer is away.
I can't find any way to relate far away to depth. Are there any? Or is the book incorrect?
Any help would be highly appreciated.