What is the difference between consolidated and unconsolidated sediments?

"Consolidated sediments" is essentially solid rock made from materials that have been metamorphosed or cemented together. For example, limestone is made of oceanic deposits of billions of shells; likewise, sandstone is made of tiny grains of sand. Ground water flows through fracture networks and/or pore space in these consolidated sediments. Consolidated sediments are sedimentary rocks, including conglomerate, sandstone, siltstone, shale, limestone, and coal. Geologic processes over time can fold, break, erode, and change (metamorphose) sedimentary rocks.

Unconsolidated sediments are loose materials, ranging from clay to sand to gravel. Ground water flows through spaces between the grains. Geologic processes can likewise erode and metamorphose unconsolidated sediments. Earthquakes, for example, can liquefy unconsolidated sediments (but not consolidated sediments).

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Aquifer basics