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shale
Oil shale, Messel Pit, near Darmstadt, Germany.
shale
rock
- Related Topics:
- shale gas
- shale oil
- black shale
- clastic rock
shale, any of a group of fine-grained, laminated sedimentary rocks consisting of silt- and clay-sized particles. Shale is the most abundant of the sedimentary rocks, accounting for roughly 70 percent of this rock type in the crust of the Earth. Shales are often found with layers of sandstone or limestone. They typically form in environments where muds, silts, and other sediments were deposited by gentle transporting currents and became compacted, as, for example, the deep-ocean floor, basins of shallow seas, river floodplains, and playas. Most shales occur in extensive sheets several metres thick, though some develop in lenticular formations. Shales ...(100 of 326 words)