Loose sediment, like that shown in (A) may someday become a rock like the one in (B) if compacted and cement fills the spaces between clasts.
Click on image for full size
(A) courtesy of Bruce Molnia, Terra and (B) courtesy of Martin Miller, University of Oregon

Step 4: Lithification (From Pile of Sand to Solid Rock)

Sediment that has formed, been transported, and deposited, is not a sedimentary rock unless it is all bound together. The process of sediment becoming a rock is called lithification. It can take tens to hundreds of thousands of years.

The material that holds sedimentary particles together into a rock is called cement. Like the cement that holds bricks together in a wall, the cement in a sedimentary rock holds the bits of sediment together. However, the cement that holds a sedimentary rock together is a bit different because it is made of mineral crystals that form in-between the clasts and holds them together. Mineral crystals form from seawater or groundwater that travels through the empty spaces in-between clasts. The mineral precipitates out of water that contains the necessary chemical ingredients. Minerals like calcite, quartz, and sometimes hematite form the cement in sedimentary rocks.

Compaction also helps a pile of sediment to become a sedimentary rock. Compaction occurs when a layer of sediment is buried under other, younger layers of sediment, the clasts become squished closely together, filling in some of the porosity, the empty space between clasts.

Last modified August 25, 2003 by Lisa Gardiner.

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

What Is a Mineral?

Minerals occur naturally on rocky planets and form the building blocks of rocks. They are non-living, solid, and, like all matter, are made of atoms of elements. There are many different types of minerals...more

Calcite

Calcite is typically found in the sedimentary rock called limestone. It can also be the cement that holds other sedimentary rocks, such as sandstone, together. Outside the sedimentary rock spectrum, calcite...more

Quartz

Quartz is the second most common mineral in Earth’s crust. It is a member of the quartz group, which includes less common minerals such as opal, crystobalite, and coesite. Silica (Si) and Oxygen (O) are...more

Hematite

A sample of hematite may look like little more than a dark gray blob. That might seem impossible to identify but with a streak test, you can easily identify it! To tell if it is hematite, just rub the...more

Step 2: Erosion and Transport (Sediments on the Move!)

Sneeze into a pile of dust and the particles fly everywhere. Sneeze into a pile of rocks and they stay put. That’s because they have more mass. You need more force than a sneeze to move those rocks. Wind...more

Step 3: Deposition (Sediments Settling Down!)

When water or wind loses energy and slows down, sediment can no longer be carried in it. The particles of sediment fall through the water or air and form a blanket of sediment on the bottom of a river,...more

Organic Sedimentary Rocks

The sediment in an organic sedimentary rock is made of fossils! The mineral parts of animals, such as bones and shells, are much more likely to be preserved than the soft tissues, which typically decay....more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA