sediment bed

例句：

1. 1. The ancient city is located on the top of a stratified sediment bed.
   这个古城位于一个分层的沉积床上。
2. 2.The geologists found evidence of ancient rivers flowing over the stratified sediment bed.
   地质学家发现了河流在分层的沉积床上流动的证据。
3. 3. The scientists are studying the effects of human activities on the stratified sediment bed.
   科学家们正在研究人类活动对分层沉积床的影响。