Sandstones generally make good aquifers, while finer-grained mudstones are typically impermeable.
砂岩通常是良好的含水层，而细粒泥岩通常是不透水的。
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Scientists have dated sharp-edged flakes of stone found in the fine-grained sediments of a dry riverbed in the Afar region of Ethiopia to between 2.52 and 2.60 million years ago.
Chondrules and inclusions in Allende are held together by the chondrite matrix, a mixture of fine-grained, mostly silicate minerals that also includes grains of iron metal and iron sulfide.