ash deposition

例句：

1. 1.The fire had left a large amount of ash deposited on the ground.
   火灾留下了大量的灰烬，堆积在地上。
2. 2.The scientist collected samples from various ash deposits for further analysis.
   科学家从各种灰烬中收集样本以进行进一步分析。
3. 3.The ash deposits are believed to have formed millions of years ago.
   据信这些灰烬沉积物是在数百万年前形成的。