Sedimentary Rock FormationEQ: How do I identify sedimentary rocks?

SEDIMENTARY ROCKS

• Sedimentary rocks are formed when sediments that have been weathered, eroded and then deposited become compacted and cemented together.

• Vocabulary Help1. sediments-small, solid pieces of material that come from rocks or living things.2. weathering-wearing away or breaking down into smaller and smaller pieces3. erosion-moving, transporting, or carrying away sediments to another place (caused mostly by wind, water, or ice)

4. deposition-place of settling5. compaction-pressing or pushing down (caused by pressure from layers of sediments above and the weight of the water)6. cementation-stick together and harden

• Sedimentary Rock Simulation

Compaction

Cementation (Crystallization)

Common Characteristics

• most are found on the exposed surface of Earth

• stratification - visible layers with oldest layer usually found on bottom

• may contain fossils• Many form underwater• May have ripple marks

TYPES OF SEDIMENTARY ROCKS

1. Detrital-forms from broken fragments of other rocks-grouped by size of particles

Examples of Detrital Sedimentary Rocks

• Conglomerate-large rounded sediments

• Breccia-large sharp or jagged sediments

Examples of Detrital Sedimentary Rocks

• Sandstone-sand size particles

• Siltstone-silt sized particles

• Shale-tiny particles of clay or mud

Found in the Real World

• Sandstone

TYPES OF SEDIMENTARY ROCKS

2. Chemical-forms from dissolved minerals that crystallize-sea or lake water evaporates leaving minerals behind that crystallize together-ex.

limestone rock salt

TYPES OF SEDIMENTARY ROCKS

3. Organic-forms from the remains of once-living things

-often contains fossils

Examples of Organic Sedimentary Rocks

• coquina-rock completely made of shell fragments

• chalk-made of microscopic shells

• coal (used for energy)-forms when pieces of dead plants are buried under other sediments in swamps over a period of millions of years

And the rock cycle continues…

• Sedimentary rock an be uplifted and exposed to the surface-possibly as parts of mountains only to be worn away again by weathering and erosion