Earth Sciences 1022a Lecture Brief 2 Oct 09 SEDIMENTARY ROCKS Weathered material from various rocks forms sedimentary rocks that comprise 75% of all rocks on the continents after deposition, sediment undergoes physical, chemical, and biologic changes as it gets turned into rock (hardened, consolidated); lithification includes compaction- pore space is reduced and particles are pressed closer together cementation – precipitate from solution onto grains, fill pores, cement grains together Detrital Sedimentary Rocks: formed from rock fragments and minerals deposited by rivers, glaciers, wind, gravity; mainly made of clay minerals and resistant quartz shale is the most abundant sed. rock made of silt and clay deposited in quiet water in lakes, river floodplains, lagoons; grains packed together so water and oil cannot flow through, good cap rock for oil and gas – also used for pottery, bricks, tile sandstone made of sand grains of mainly quartz, if grains about the same size it is
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Sedimentary rocks, chemical sedimentary rocks, Detrital sedimentary Rocks, forms sedimentary rocks, SEDIMENTARY ROCKS Weathered