Sedimentary RocksSedimentary Rocks

Made from Sediments!!Made from Sediments!!

AIM:AIM: What are the What are the characteristics of sedimentary characteristics of sedimentary rocks?rocks?• Sedimentary rocks are formed from Sedimentary rocks are formed from

the accumulation and the accumulation and lithificationlithification of sediments of sediments

Sed RocksSed Rocks

• There are 3 types of sedimentary There are 3 types of sedimentary rocks:rocks:

– Clastic Clastic sedimentary rocks are formed sedimentary rocks are formed from clay, sand, and gravel (fragments)from clay, sand, and gravel (fragments)

– Crystalline Crystalline sedimentary rocks are sedimentary rocks are formed from mineral grains and crystals formed from mineral grains and crystals thatthat precipitate precipitate out of solution by out of solution by evaporation or chemical actionevaporation or chemical action

– Bioclastic or Organic Bioclastic or Organic rocks are formed rocks are formed from the remains of plants and animalsfrom the remains of plants and animals

Clastic RocksClastic Rocks

• Clastic RocksClastic Rocks – the particles – the particles consist of weathered existing rocks.consist of weathered existing rocks.

• Particle sizes varyParticle sizes vary

Clastic Sed RocksClastic Sed Rocks

•Large accumulations of clastic of clastic sediments exist where rivers meet sediments exist where rivers meet still bodies of waterstill bodies of water

Clastic Sed RocksClastic Sed Rocks

• Clastic rocks are Clastic rocks are lithified by by compaction and and cementation

• Compaction occurs when the weight of occurs when the weight of overlying sediments compresses the material overlying sediments compresses the material and and squishessquishes out most of the water out most of the water

• CementationCementation occurs when dissolved occurs when dissolved minerals minerals precipitateprecipitate in the pores between in the pores between the particles and glue them together. Ex: the particles and glue them together. Ex: silica, calcite, silica, calcite, hematite

Crystalline Sed RocksCrystalline Sed Rocks

• Crystalline RocksCrystalline Rocks – the minerals – the minerals dissolved in solution are dissolved in solution are precipitatedprecipitated from water by from water by evaporation or chemical action.evaporation or chemical action.

Bioclastic Sed RocksBioclastic Sed Rocks

• Bioclastic or OrganicBioclastic or Organic rocks are rocks are formed from accumulations of formed from accumulations of remains of living things. YES, rocks remains of living things. YES, rocks made of dead stuff made of dead stuff

Sed Rocks – Secondary Sed Rocks – Secondary FeaturesFeatures

• Secondary Sedimentary Secondary Sedimentary FeaturesFeatures: see these in a rock and : see these in a rock and it’s probably sedimentary.it’s probably sedimentary.

• StratificationStratification – the arrangement – the arrangement of sedimentary rock in visible layers of sedimentary rock in visible layers that may separate easilythat may separate easily

Sed Rocks Secondary Sed Rocks Secondary FeaturesFeatures

• Fossils Fossils – the remains, impressions, – the remains, impressions, or any other evidence of the or any other evidence of the existence of life preserved in the existence of life preserved in the rockrock

Sed Rocks Secondary Sed Rocks Secondary StructuresStructures

• Ripple MarksRipple Marks – seen on the – seen on the surface of a bed of sandstone surface of a bed of sandstone formed from wave action on the formed from wave action on the sand sediment before lithificationsand sediment before lithification

Sed Rocks Secondary Sed Rocks Secondary StructuresStructures

• Mud Cracks – these develop when Mud Cracks – these develop when deposits of wet clay dry out and deposits of wet clay dry out and crack. Cracks often fill with crack. Cracks often fill with different materialdifferent material