Sedimentary RocksSedimentary Rocks

OriginOrigin Comprise 75% of the Earth’s surfaceComprise 75% of the Earth’s surface Formed when sediments become Formed when sediments become

compacted and cemented togethercompacted and cemented together Usually has layers called strataUsually has layers called strata

The highest layer has the The highest layer has the least pressure. least pressure.

The lowest layer has the The lowest layer has the most pressure.most pressure.

CompactionCompactionWhat does What does

compaction compaction mean?mean?– Layer upon layer of Layer upon layer of

sediment builds up and the sediment builds up and the pressure from the upper pressure from the upper layers pushes down on the layers pushes down on the lower layers.lower layers.

– Only SMALL sediments will Only SMALL sediments will stick together to form rockstick together to form rock

CementationCementation

What does it mean?What does it mean?– Water soaks through soil and rock. The Water soaks through soil and rock. The

water dissolves minerals in soil and water dissolves minerals in soil and rock. rock.

– The solution of minerals and water The solution of minerals and water moves between the sediments. moves between the sediments.

– The sediments stick together when the The sediments stick together when the minerals crystallize.minerals crystallize.

– Common with LARGE sedimentsCommon with LARGE sediments

ClassificationClassification

Sedimentary rocks are classified in Sedimentary rocks are classified in 3 ways…3 ways…

1. Clastic Sedimentary Rocks1. Clastic Sedimentary Rocks

2. Chemical Sedimentary Rocks2. Chemical Sedimentary Rocks

3. Organic Sedimentary Rocks3. Organic Sedimentary Rocks

It’s by the way they are formed!!!

WHAT?

Clastic Sedimentary RockClastic Sedimentary Rock

Made from broken fragments of other Made from broken fragments of other rocks.rocks.– ConglomerateConglomerate = large/round fragments = large/round fragments– BrecciaBreccia = large/sharp fragments = large/sharp fragments

Breccia Conglomerate

Chemical Sedimentary RockChemical Sedimentary Rock

Formed from minerals crystallizing Formed from minerals crystallizing out of a solution out of a solution

The solution is made of minerals and The solution is made of minerals and water.water.

Halite (Rock Salt)

Organic Sedimentary RockOrganic Sedimentary Rock

Rocks formed from once-living Rocks formed from once-living (organic!) things.(organic!) things.

Organic LimestoneOcean animals called coral create huge deposits of limestone. As they die, their skeletons collect on the ocean floor.

StratificationStratification The process in which sedimentary The process in which sedimentary

rocks are arranged in layers. rocks are arranged in layers.

Stratification