The shale roof-made of the sediment that destroyed the forest so long ago-is cracking and flaking off now that the coal below it has been removed.

页岩层顶部是由远古时候掩埋森林的沉积物构成。由于埋藏其下的煤已经被挖走，所以这些页岩有开裂和剥落现象。

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J. suggests, a lot of Republicans who are flaking off this thing.

NPR: Week in Washington: Change and Strategy

These stone tools generally consisted of sharp flakes battered off a stone core, but early hominids also did more sophisticated flaking and retouching to sharpen and straighten their blades.

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