Sediment (A) may someday become a clastic rock (B) if compacted and cemented together.
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(A) courtesy of Bruce Molnia, Terra and (B) courtesy of Martin Miller, University of Oregon
Step 4: Turning a Pile of Sediment into Solid Rock!
Sediment is not a sedimentary rock unless the little grains become stuck together. The material that holds sediment together into a rock is called cement. Cement is mineral that forms when seawater or groundwater travels through the empty spaces between sediment. If the water contains the chemicals that are needed, mineral crystals will form in-between the sediment. The mineral holds the sediment together. Minerals like calcite, quartz, and sometimes hematite form the cement in sedimentary rocks.
A pile of sediment becomes a sedimentary rock more quickly when it is buried deep underground. This makes the sediment grains become squished closely together. However, the whole process can take tens to hundreds of thousands of years.
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The Fall 2010 issue of The Earth Scientist
, focuses on rocks and minerals, including articles on minerals and mining, the use of minerals in society, and rare earth minerals, and includes 3 posters!
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