GEOL 1425 1st Edition Lecture 9 Outline of Last Lecture I. Magmatic differentiationII. Bowen’s reaction seriesIII. Magma chambersIV. What to know for test about Igneous rocks…Outline of Current Lecture I. About sedimentationII. Processes forming sedimentary rockIII. Some sedimentary environments Current Lecture—Sedimentary Rocks II. About sedimentationA. Not all to do with rocks, some are the remains of organisms—limestone made of shells.B. Gypsum, halite, regular table salt—all produced from the evaporation of water from saline. C. Most sediments are produced from weathering of the earths materials. The size and material will determine how far the particles will be transported. Eventually the smaller sediments will have other things deposited on it and sedimentary rocks will be formed. D. Age of rocks can be determined by appearance—sediments are very useful for relative age-dating.II. Processes forming sedimentary rockA. Weathering – Mechanical weathering is a general process by which rocks are broken down at earth’s surface to produce sediment particles.These 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.Chemical weathering occurs when the minerals in a rock are chemically altered or dissolved.—chem weathering causes blurring/disappearing of gravestone lettersi. Physical and chemical weathering reinforce each other ii. Physical weathering- ex-water getting into cracks of the rocks and eventually breaks it apartiii. Chemical weathering—limestone can be weathered. Rain water that’s acidic can easily erode it. Of statues. The smaller the particle, the greater the surface of the particle that is exposed to chemical weathering.B. Erosion- Carries particles away, gravity drives erosion. Pull of gravity is lower in lowlands (less energy) and higher in mountains (more energy). Glaciers are major components of erosion when present and work very quickly compared to other components.C. Transportation—Moves particles downhill. when currents of wind and water andthe moving ice of glaciers transport particles to new locations. Sediment sinks and/or travels downhill or upstream. Again, less energetic environments cause less transportation than high-energetic environments. D. Deposition (aka-sedimentation)—Dropping off sedimentary particles. This is when particles form layers of sediment on land of under the sea in sedimentary basins—till deposits. high-energy environments will be able to depose at a greater rate than low-energy environments. Further out in the oceans the sediment layers will be much thinner, and closer to the coast/land the sediment will be much thicker due to higher deposition in those areas. E. Burial and compaction—occurs as layers of sediment accumulate in sedimentary basins and older, previously deposited sediments and are compacted and buried deep. These particles will stay buried for a long time, unless for some reason the earth causes them to re-surface, sometimes in a different form. They sometimes metamorphose into different types of rock. F. Digenesis—a chemical aided by heat and pressure, modification of the sediment in that place. Causes lithification of the sediment, making sedimentary rocks. III. Some sedimentary environments:A. Glacier- major depositional and erosive aspectsB. River- river loses its energy and things get deposited. i. Mississippi- “I sometimes think the river is a god, a great brown god” WB YatesC. DeltaD. Desert- things get eroded by the wind and become smaller things. Wind is helpful in eroding because it can serve to sand blast materials. E. Lakes and playasF. Marine shelfIV. Classification of sediments:A. Siliclastic sediments—physical and chemical weathering of rocks forms clastic particles, transported and deposited as clastic sediments. Variations in size and shape and mineral composition. Quartz resists weathering and is often un-altered in siliclastic sediments. Clay minerals may be newly formed. B. Chemical sediments—form often in arid climates. Minerals in a solution are transported where theyre accumulated in a water body. As the water evaporates, the dissolved chemicals become concentrated and evaporite deposits are formed. C. Biological sediments—the result of mineral precipitation within organisms as they grow. After the minerals die, their shells deposit and form sedimentary rocks. The organism, then, determines mineral precipitation. Biological stuff tends to stay around where the organism’s climate was, but silicalstic sediments can move a long distance from their origin. V. Transportation and depositionA. Sorting of clastic particles—the larger particles are settle faster than smaller ones.B. Gravity drives everything