To make the aces,sources of suitable stone
had to be found systematically expoited.These so-called "axe factories"were really quarries rather tahn factories,as the manufacture of
the axes wasn't regularly performed on the
quarry site.However,after the axe had been
chipped into shape,they needed water and
sand for grinding and polishing,so a high
mountainside wouldn't have been an
appropriate place for this.
我搞不懂为什么说因为他们的制造通常不再采石场 所以就叫做quarries rather tahn factories呢？

than， 不是tahn， 写错了。第一句的aces也应该是axes。
你的问题的答案就在原文中，问题就是答案：as the manufacture of the axes wasn't regularly performed on the quarry site.
因为factory是工厂的意思，就是制造某种东西的地方。 既然斧头不是在采石场制造的，那采石场也就只是个采石场，而不是一个制造工厂。只能说是 so-called 所谓的"axe factories"-
不知道这样的解释你觉得通不通？