Earth Science Q2 PDF

## Earth Science Q2 ### Weathering * process by which rock is broken into smaller pieces * **Physical (Mechanical) Weathering** * breakdown of rock into smaller pieces, no chemical change * **Frost Action/Wedging, Freeze-Thaw Cycle** * expansion of freezing water *...

## Earth Science Q2 ### Weathering * process by which rock is broken into smaller pieces * **Physical (Mechanical) Weathering** * breakdown of rock into smaller pieces, no chemical change * **Frost Action/Wedging, Freeze-Thaw Cycle** * expansion of freezing water * **Thermal Expansion** * repeated heating and cooling cause rocks to crack and break * **Exfoliation** * peeling away of rock * due to unloading (reduced pressure) or fluctuations in temperature * **Abrasion** * rocks colliding/bumping against each other * **Agents:** * Wind * Liquid water * Solid water * Gravity * **Biological** * plants, expanding (uplift & fracture) of seeds and roots in a process called Root Action * lichen and moss, secrete acids that chemically break down rocks * animals, soil burrowing creatures (such as earthworms) * **Chemical Weathering** * chemical change in the rock * **Hydration** * water combines with minerals * Ex: Feldspar >> Clay * **Carbonation** * water containing carbonic (weak) acid dissolves minerals (calcite minerals) * Ex: Stalagmites (ground) & Stalactites (ceiling) * **Man Made Acids** * Nitric & Sulfuric Acid (industrial processes, causes chemical weathering of structures) * **Oxidation** * oxygen is added to other elements * rusting of magnetite into hematite * common in metallic elements and ores such as Iron (Fe) ### Rates: * **Climate** * faster at higher temperature * requires water * **Rock Type** * "Quartz" (resistant to chemical weathering) ### L2: Earth's Internal Heat * **Different Theories:** * **Big Bang Theory** * universe started with a single point (singularity) * expanding and cooling * Hydrogen and Helium (responsible elements) * **Stellar Theory** * stars are basic building blocks of universe * **Super Nova Nucleosynthesis** * explosion of massive star * **Big Crunch Theory** * opposite of Big Bang * universe will stop growing, begin to shrink, got hotter * **Sources of Heat:** * **Primordial Heat** * dissipation in a planet during its first few million years of evolution * + Accretion/Accretional Energy (initial formation of the Earth) * **Radiogenic Heat** * thermal energy as a result of spontaneous nuclear disintegration * disintegration of natural radioactive elements inside the Earth such as Uranium (U) and Thorium (Th) * "Uranium (U)" — special kind of element because when it decays, radiogenic heat is produced. * + Isotopes * atoms with same number of protons but different number of neutrons ### L3: Magmatism * **Magma** * semi-liquid hot molten rock beneath the Earth, in the melted rock and oceanic plate * temperature is between 700°C - 1300°C * when reached the Earth's surface, lava * when solidifies, creates igneous rocks * originates in the lower crust and upper mantle * Oxygen is the most abundant element * **Magmatism** * process under the Earth's crust, formation and movement of magma * occurs in the asthenosphere (upper mantle below the crust) through convection currents ### How do magmas formed? * **Partial Melting** * different minerals melt at different temperature and pressure * addition of volatile materials such as water and carbon dioxide * **Conditions:** * **Increase in temperature.** * • Conduction * heat is transferred from hotter molten rocks to Earth's cold crust * known as Heat Transfer that happens in convergent boundaries * **Decrease in pressure.** * • Convection * rocks tend to go upwards, pressure is reduced, triggers the melting of magma * this process is known as Decompression Melting that occurs at Mid-Ocean Ridge (underwater mountain system) * **Addition in volatile.** * • Flux Melting * water or carbon dioxide is added to hot rocks * melting point decreases * occurs around subduction zone ### L4: Metamorphism * **Metamorphism** * from Greek, Meta-change & Morphe-form (change in form) * **Metamorphic Rocks** * rocks subjected to either enough heat or pressure * never melt, if they did, it would become igneous magma, changes are solid state * **Changes Occurs:** * in the minerals * folding and bending of rocks, change in shape * recrystallization * chemical reactions to new minerals that are more stable at pressure and temperature as a result of polymorphic phase transformations * **Agents and Factors:** * **Heat** * most important agent * geothermal gradient increases in temperature at 30°C/km * • Geothermal Gradient * rate at which temperature increases with depth in Earth's crust * **Pressure** * increases with depth, 1000 kg/cm² at 4km depth * minerals to melt or atoms to configurations that represent tighter packing * **Confining/Vertical Stress (Lithostatic)** * equal pressure in all directions * cause to become smaller, rocks are fractured and deformed * **Directed/Differential Pressure/Stress** * not equal pressure in all directions * shape and orientation of new crystals formed * **Protolith** * parent rock * original, unmetamorphosed rock * **Low-grade Metamorphism** * non-foliated rocks, not/no visible crystal alignments, smooth surfaces, and breaks easily * Ex: slate * **High-grade Metamorphism** * foliated rocks, visible crystal alignments * Ex: schist, gneiss * **Time** * changing the rock while it's solid, slow process (tens of millions of years) * coarse-grained involve long times * **Fluid Phase** * open space between mineral grains contain a fluid * mostly H2O, contains dissolved ions (charged particles) * speeded up by dissolved ions transported by the fluid * + Metasomatism * chemical alteration of rock as a result of these fluids * **Types of Metamorphism** * **Regional** * foliated rocks such as Gneiss and Schist * high temperature and pressure on large parts of crust * occurs within the continental crust