最大的石头每块重五吨以上。

The largest stones weigh over five tonnes apiece.

《牛津词典》

如果你改变的事情它自己也能造成进一步的改变，将产生最大的效果--引起许多石头崩溃的那块石头。

You’ll have the biggest impact if you can change something that will in itself cause further changes — the rock that causes the avalanche.

youdao

所以说，这些石头大概就是在每隔几年出现的那些最冷风又最大的日子里移动的。

So, the rocks are probably traveling on the coldest and windiest days that occur over a period of several years.

youdao