Now, I don't know the song and it may help to know what comes after those lines and this explanation may be a little far fetched, but .........

If you think of the Australian outback as being very big, and another way of saying "very big" is "GREAT" and as the outback vitually contains a whole lot of nothing and another way of saying that is "F*CK ALL" then it could read as:

not much in the Great F*ck All but a pile of rusty sand.

Then again, I haven't got a clue.

Allan