EES 1030 Lecture 6 Outline of Last Lecture I. Lecture 5: Weathering & SoilII. Breakdown of Rocks at Earth’s SurfaceIII. Earth’s External ProcessesIV. Two Types of Weathering ProcessV. Mechanical WeatheringVI. Chemical WeatheringVII. Chemical Weathering: Acid RainVIII. Chemical Weathering: HydrolysisIX. Chemical Weathering: OxidationX. Chemical Weathering: ProductsOutline of Current Lecture XI. Lecture 6: Sediments and Sedimentary RocksXII. Sedimentary RocksXIII. Sediments vs. Sedimentary Rocks:XIV.Types of Sedimentary RocksXV. Detrital Sedimentary RocksXVI. Chemical Sedimentary RocksXVII. Sedimentary StructuresCurrent LectureSedimentary Rocks:Product of mechanical & chemical weathering75% of rocks at Earth’s surface are sedimentary but only 10% of outer 15 km.Contain evidence of past environments.Only rock type to contain fossils.Economically important: host oil, gas, uranium and coal deposits. Source of sand and gravels for constructionSediments vs. Sedimentary Rocks:Sediments: collection of loose, solid particlesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Sedimentary rock: particles bound together to form a firm, coherent rock.Lithification: unconsolidated sediment to rock.Types of Sedimentary RocksDetrital: sediment transported as solid particles. Examples: sandstone, shaleChemical: sediment formed from material that was once in solution in water. Examples: limestone: inorganic and biologicalOrganic: remains of decayed plants: Examples: peat, coal.Detrital Sedimentary RocksMain constituents are: clay minerals, quartz, feldspar, mica, and rock fragments.Particle size: used to distinguish types.Particles > 2 mm in diameter.Conglomerate: rounded particles.Breccia: sharp, angular particles.Sand-sized particles 0.0625 to 2 mm.Sandstone: Quartz is dominant mineral.Fine particles <0.0625 mm: Mudstone/ShaleSiltstone & Clay stone: test by chewing rock!Shale: silt and clay particles from think layers or laminae during compaction.Shales, Siltstones, Mudstones: difficult for water to penetrate  little cementation  poorly lithified and friable  crumbles easilyChemical Sedimentary RocksMaterial that was once in a solution.Precipitation occurs by: Inorganic processesProcesses (biochemical origin) organic processesLimestone: most abundant chemical rock.Composed mainly of mineral Calcite or its polymorph Aragonite.Oolitic Limestone: inorganic.Form in warm, shallow, agitated waters.Biogenic Limestones: coral reefs, shell fragments, microorganisms.Coquina: poorly cemented rock of shell fragments.Fossiliferous Limestone: shell fragments cemented with calcite cement.Biogenic Limestones: microorganismsExamples: Chalk: made from tiny shell fragments of planktonDolostone: made of Dolomite CaMg(CO3)2 forms from limestone as Mg-rich water passes through rock. Calcite: CaCO3 vigorous fizzing with dil. HCI acid.Dolomite: CaMg(CO3)2 no fizzing with dil. HCI acid.Chert: hard, compact, microcrystalline SiO2.  nodules & layers, often in limestone beds.Also known as flint. Used by ancient cultures to make tools and arrowsEvaporites: evaporation of water triggers deposition of chemical precipitates. Example: Halite (rock salt), gypsum, carbonatesSedimentary StructuresMud crack: evidence that sediment was alternately wet then dry. Wet mud shrinks as it dries out, forming cracks.Geographic setting where sediment accumulatesDetermines the nature of the sediments that accumulate (grain size, grain shape, etc.)Continental environments: Rivers, Lakes, Deserts, GlacialShoreline environments: Delta, beach, tidal flatsMarine: environments: Deep sea, continental shelf, organic