请问这个句子的主干是什么？

您好~

This abundance?is notable in Roman settlements (especially urban sites) where the labor that archaeologists have to put into the washing and sorting of potsherds (fragments of pottery) constitutes a high proportion of the total work during the initial phases of excavation.

本复合句中，主体为“This abundance?is notable in Roman settlements (especially urban sites)?”这种丰度（富裕度）在罗马人的定居点（尤其是在城郊的地点）是值得让人注意的。

定语从句：句子剩余后半段是一个以settlements为先行词，用“where”引导的一个限制性定语从句，其主体为the labor constitutes ......这个工作/劳动包含在发掘的最初阶段期间的很大一部分工作中，而这个工作正是句中用that引导的限制性定语从句“archaeologists have to put into the washing and sorting of potsherds (fragments of pottery)?”。

总之，这是一个由一个主句、两个定语从句叠加的复合句。

请采纳~