My Science School

          Sedimentary rocks are formed from the sediment, or broken pieces of the earth's rock structure worn down by weather and erosion. The fragmented pieces become compacted and in time much of it is cemented in to form rock.

          Igneous rocks originate either from volcanic action as molten lava, which hardens, or from the slow cooling of molten masses beneath the earth's surface, which exposed after a volcanic eruption on or after much erosion.

          Many important minerals, not­ably uranium, have been found, enveloped in igneous rocks. The chief sedimentary rocks are sandst­one, shale, dolomite and lime­stone.

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