Sedimentary Rock
Formation
EQ: 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 Help
1. sediments-small, solid pieces of material that come from rocks or
living things.
2. weathering-wearing away or breaking down into smaller and smaller
pieces
3. erosion-moving, transporting, or carrying away sediments to
another place (caused mostly by wind, water, or ice)
4. deposition-place of settling
5. 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