The forest floor is the lowest layer full of animal life and receives the least amount of light.

地面层是最底层，那里满是动物，接收到的光线最少。

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Sediment cores are essentially a record of sediments that settled at the sea floor, layer by layer, and they record the conditions of the ocean system during the time they settled.

沉积物岩心主要记录的是沉淀在海底沉积物，一层又一层，记录它们沉淀时的海洋系统状况。

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Squidworms live about 100 to 200 meters (328 to 656 feet) above the ocean floor, a layer rich in undiscovered fauna and flora, scientists say.

科学家说，这种鱿鱼蠕虫生活在海底以上约100米到200米(328到656英尺)之间，这个空间层面里还存在着许多未被发现的动植物。

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So did a thick, solid layer of sheep dung covering the floor.

VOA: special.2010.08.03

Methane is the principal component of natural gas, and massive amounts of it are trapped in reservoirs beneath the sea floor and under a layer of the ice-like substance.

FORBES

The archaeologists put the shoe's remarkable preservation down to the stable, cool and dry conditions in the cave and the fact that the floor of the cave was covered by a thick layer of sheep dung.

BBC: 'Oldest leather shoe' discovered

The final layer is often panels of loose-weave or sheer fabric hanging in soft drapes to the floor.

WSJ: Sheer Curtains, Solar Shades Are Popular Window Treatments