Originally Posted by Scootermuze

Compacted material burning in a pit would use up the oxygen quick.. and never get a fire hot enough to melt anything..

The only source for oxygen would be from the top, and oxygen would only feed the upper portion of the compacted material and not reach the lower portion.

If you've ever burned anything in a barrel, you should have noticed how weak a fire is due to the lack of oxygen getting to the source..

Just another hint..