sedimentary rocks

four major clasts of sedimentary rocks

*clastic, *biochemical, organical, chemical

formation of sedimentary rocks

weathering —> erosion —> trasportation —> deposition —> lithification

physical weathering

physically changing/breaking rocks apart: jointing, front wedging, root wedging

chemical weathering

chemical reactions alter rock: dissolution, oxidation, hydration

erosion

process by which wind, water, ice, or gravity removes soil, rock, or sediment from one location

transportation

the actual movement or transportation of the eroded materials, by rivers, wind, ice/glaciers, gravity

deposition

process by which eroded materials like sediment, soil, or rock fragments are laid down in a new location

lithification

process by which loose sediment is compacted and cemented together to form sedimentary rocks

two parts in lithification

compaction and cementation

two important things in classifying sedimentary rocks

clast angularity

what does clast size tell you about sedimentary rocks

how far away the sedimentary rock was formed from the source rock

what does angularity tell you in sedimentary rocks

how much weathering has happened

coarse to very coarse sedimentary rock

conglomerate (rounded clasts), breccia (angular clasts)

medium to coarse sedimentary rock

sandstone

fine sedimentary rock

siltstone

very fine sedimentary rock

shale (platy sheets), mudstone (no sheets)

Formation of biochemical sedimentary rocks

organisms make shells —> shells die —> shells remain —> lithification (limestone)

sedimentary structures

mud cracks, scour marks, fossils, cross bedding, ripples

cross bedding

forms when inclined sediment layers are deposited by wind or water currents, commonly indicative of environments like river channels, deltas, or desert dunes

depositional environments

where grain sizes are transported to before lithification

terrestrial environments

glacial, alluvial fan, desert, lakes, rivers

transitional environments

delta, marsh, shoreline, river mouth

marine environments

lagoon, reef, deep ocean

coarse to very coarse clasts

terrestrial: mountain, alluvial, glacial, rounded clasts

medium to coarse clasts

terrestrial and transitional: beaches, riveres, deserts, sandstone with ripples or cross bedding

fine clasts

transitional and marine, lakes, floodplains, deltas, submarine fans, siltstone, mudstone with mudcracks

very fine clasts

marine and transitional, deep marine/ocean, tidal flats, mudstone, shale

sea level rise

grain size decreases

sea level fall

grain size increases