Some rocks from volcanoes break down to form black sand.

有些火山岩被撞碎后会形成黑色的沙。

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It is difficult to determine the effects of straw-break surface on the structure of drifting sand current and the wind speed profile in the sand-moving region due to the complexity of straw-breaks.

由于草方格构成的下垫面复杂多变，其对风沙流结构与风沙活动层风速廓线的影响很难确定。

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Big low stand fan sand bodies that have been found distribute along the circle belts and were controlled by fault break slopes.

已发现的大型低位扇体沿环带分布，并受断裂坡折带的控制。

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More than 10 drillers have already received Department of Environmental Protection permission to use mine discharges for fracking, a technique in which millions of gallons of water, along with chemical additives and sand, are pumped down a well to break apart gas-bearing shale deposits.

WSJ: Pa. pushes drillers to frack with coal mine water