(gathered by farmers clearing their fields) were a cheap and durable roofing material.

（由清理田地的农民收集）是一种廉价耐用的屋顶材料。

So they had to content themselves with clearing fields, grazing animals, and chopping down trees.

因此，他们不得不满足于清理田地、放牧和砍伐树木。

Here the goal is to do the reverse, clearing the mine fields will preserve these holy sites.

这里的目标是相反，清除雷区将保护这些圣地。