1Accumulation; piling up of materials—things, goods, dust, etc.—forming heaps or layers.
倉庫に在庫が堆積している。
Inventory is piling up in the warehouse.
部屋の隅に古い雑誌が堆積していた。
Old magazines had accumulated in the corner of the room.
2Sedimentation (geology): deposition of sediments transported by water, wind, etc., forming layers over time.
川の河口に大量の土砂が堆積した。
A large amount of sediment accumulated at the river mouth.
地層の堆積は長い時間をかけて進行する。
The deposition of strata proceeds over a long period of time.