The wood was stacked, chopped, weighed and carried down to the water again, probably weighed again. Each cremation required a ton of wood. Ton in the sense of a lot, not a specific unit of measurement
I think it´s an subtle clarification of the term ton, unnecessary, but subtle. Nowadays, a ton is equal to a thousand kilos, but its name and its origin are quite confusing because of its relation with the whimsical English imperial units.
The text could have told us about the diferences between a literal ton and a metaphoric one. Curiously, when teenagers, in their current language, say literally a ton, they mean both meanings, because literally is used as figuratively now.