(an) accumulation, a pile; 〔地質学で〕sedimentation
堆積する｜pile [build] up; accumulate
They cleared the streets of the (heaps of) mud.／They removed the mud which had accumulated on the roads.
A huge amount of data had accumulated [piled up].／((口)) There were heaps of materials.
堆積岩｜a sedimentary rock
堆積物｜sediment; a deposit