STEM 11 Q2 Earth Science PDF

EARTH SCIENCE Grade 11 | 1st Semester | Quarter 2 Upper Mantle – cooler than lower mantle; rocks are brittle & break acted upon by force Topic Outline: Chapt...

EARTH SCIENCE Grade 11 | 1st Semester | Quarter 2 Upper Mantle – cooler than lower mantle; rocks are brittle & break acted upon by force Topic Outline: Chapter III – Earth Processes Lower Mantle – hotter; rocks are soft & flow when acted upon by  Endogenic Processes force  Exogenic Processes  Continental Drift Theory Outer Core – liquid iron & nickel due to extreme heat; source of earth’s internal heat same as sun’s surface  Plate Tectonics Inner Core – solid & hotter; extreme pressure keeps the inner core in ENDOGENIC PROCESSES solid form Geologic Processes – mechanisms involved in the formation of rocks, weathering, erosion, & plate tectonics Lithosphere – the rigid outer part of earth, consisting of the crust & part of the upper mantle  Western Deep levels gold mine (Transvaal, South Africa) – 3,777 m deep Asthenosphere – part of the upper layer of earth’s mantle, below the  Earth’s equatorial radius – 6,378 km lithosphere, it is much hotter & more fluid than the lithosphere  Seismic Technology - We can send sound waves deep into the earth and listen to them when they bounce back up  Temperature: between 1400C and 3000C using little, tiny things called geophones.  COMPRESSION MATTER  Compression of matter that compose earth  As the earth grew in mass, gravity increased  It pulls matter towards the center, resulting in the continued squeezing & compression of all materials that make-up our planet  Heavy metals like Fe and Ni, as they sink to the interior of earth,  their potential energy SOURCES Sinking of heavier OFtheHEAT metals into earth’s center transforms into kinetic  Residual heat of early planetesimals that slammed into energy, which is earth billions of years ago converted into heat  Radioactive decay within earth’s core INTERNAL STRUCTURE OF THE EARTH SINKING OF HEAVIER METALS Magma – molten rock beneath earth’s crust Lava – molten rock that has flowed out onto the earth’s surface Formation of Magma  Melting by decompression – decrease in pressure; pressure prevents melting, decompression permits melting. o This occurs when hot mantle rock rises to shallower depths. Once rocks begin to melt, they turn into magma that rises up because Continental Crust – more dense; made from granite (30 - 50 km thick) it is less dense than its surrounding environment Oceanic Crust – less dense; made from basalt rocks (5 – 7 km thick) 1 EARTH SCIENCE Grade 11 | 1st Semester | Quarter 2 form from chemical precipitates and organic growths that accumulate FORMATION OF MAGMA at the bottom.  Melting due to volatiles – elements/compounds that evaporate quickly (water/carbon dioxide), when they Metamorphic Rocks – form when pre-existing change into new rock mix with hot rocks, they weaken & break the bonds of an increase in temperature & pressure that hold the atoms of rocks together o Volatiles decrease a melting point of rocks Bedrock – rock still attached to the earth’s crust resulting in the formation of magma Regolith – a thin layer of loose rock fragments, clay, & sand  Heat-transfer melting – as magma & rocks from the mantle rises up close to earth’s crust, they bring heat Soil – upper layer of the regolith which supports plants with them o By direct heat transfer, the temperature of the surrounding environment rises up to the point where surrounding rocks begin to melt as well  Magma rising from the mantle is over 1100c; Rocks in the crust melt at temperature of only about 650 – 850 C Magmatism – process by which magma is formed; interaction with solid rocks & solidification WEATHERING  Refers to the processes that break up & corrode solid rocks, REASONS BEHIND MAGMA’S MOVEMENT transforming them into sediments A process by which matter & heat from within the earth’s internal environment are transferred to the earth’s surface PHYSICAL WEATHERING  Less dense Mechanical/Physical Weathering – breaks rock into smaller pieces by  Pressure from surrounding rocks using physical processes EFFECT CLASSIFICATION OF SEDIMENTS BASED ON SIZE - supplies earth’s surface with a raw materials needed to COURSE SEDIMENTS form the components of the four spheres: biosphere, Boulders – greater than 256 mm atmosphere, geosphere, & hydrosphere Cobbles – 64 – 256 mm - Magma that has surface turns into lava & with the passing Pebbles – 2 – 64 mm of time becomes a new land mass MEDIUM SEDIMENTS - Ex. Volatiles contained in magma are released into the Sand – 1/16 – 2 mm atmosphere as oxygen & carbon dioxide FINE SEDIMENTS Silt – 1/256 – 1/16 mm Mud – less than 1/256 mm EXOGENIC PROCESSES Detritus – decaying or organic matter; rock fragments Rock transformation – rocks are the solidified forms of molten rock that managed to reach the earth’s crust & surface either through Fresh rock – a rock whose plutonism or volcanism grains have their original composition & shape Rock – naturally occurring & coherent aggregate of one or more minerals Weathered rock – a rock that has reacted with Protolith – original rock; do not react singly w/ either temperature or air/water near the earth’s pressure surface Igneous Rocks – form when molten rocks solidfy due to a decrease temperature Sedimentary Rocks - when fragments of earlier rocks, minerals, and organisms accumulate and become cemented. Under water, they 2 EARTH SCIENCE Grade 11 | 1st Semester | Quarter 2 PROCESS OF PHYSICAL WEATHERING Salt Wedging (Honeycomb/Tafoni Jointing – rocks have naturally formed cracks in its structure (Joints). Weathering) – dissolved When rock changes shape due to an increase in pressure, it breaks salt in groundwater into pieces along joints crystallizes & enlarges in open spaces/pores in Fractures – that allow water to penetrate & weather the rocks. This pushes apart rock the surrounding grains of the rock causing it crumble; when water mixed w/ salt gets into a rock & dissolved inside Animal Attack – Burrowing animals (earthworms, grasshoppers, etc.) push open cracks, and break rocks into fragments; In history, humans Frost Wedging – when water trapped in the joints of rock freezes, it who have become the most forces the joints to open, causing it to enlarge & eventually for the energetic cause of physical rock to break apart weathering CHEMICAL WEATHERING Chemical Weathering – rock changes composition & becomes a different type of rock Erosion – displacement of solids (water & ice) Exfoliation – the process by which granites gradually break intro fragments. Large plates or shells peel away like layers of onion Landslide – downward movement of earth materials, primarily due to Root Wedging – trees roots gravity can grow into joints & force them to open. Even small plants occupying these joints can put a stress on cracks, strong enough to split the rock Thermal Expansion – all matter expands when subjected to intense heat; Forest fires can be such intensity that it causes rocks to expand Wind Erosion that create a forces strong enough for the outer layer of rocks to break off; repeated heating & cooling of materials cause rigid - Turbulent Action – it removes loose & fine-grained substances to crack & separate materials - Abrasion – wears down surfaces by sandblasting them with windborne particles; carried sand can sometimes polish rock 3 EARTH SCIENCE Grade 11 | 1st Semester | Quarter 2 Water Erosion – removal of soil by water & transportation of the from rocks; the decaying remains of plants & some fungi form eroded materials away from the point of removal carbonic acid, which can weaken & dissolve rock ROCK CYCLE PROCESS OF CHEMICAL WEATHERING Dissolution – since rocks are made from minerals, the dissolution of these minerals breaks rocks apart. When rainwater is acidic, chemical weathering takes place even faster; more on in caves - Halite easily dissolve in rainwater METAMORPHISM - Calcites easily dissolve in acid rain (acid rain contains high Metamorphism – process of transformation in shape, form, or levels of nitric & sulfuric acids than rainwater; a harmful appearance form of a rain) Heat & Recrystallization – extreme heat affects the chemical Hydrolysis – when water composition of rocks such that sedimentary or igneous rocks turn into trapped in the joints of rocks metamorphic rocks. It causes the atoms of mineral crystals to vibrate freezes, it forces the joints to faster, weakening & eventually breaking the chemical bonds that hold open, causing it to enlarge & them together. When atoms detach from their old crystalline eventually for the rock to formation, they migrate to nearby spaces, where they form new break apart; when rocks sit in bonds with other atoms, & thus recrystallization occurs water for extended periods of time they begin to break down Compositional bonding – migration of atoms produces layers of & have a clay-like texture different composition Oxidation – oxidation reactions take place when elements combine Subsidence – sinking of a part of lithosphere. It leaves behind a w/ oxygen. (e.g. rusting) It turns into depression (depression basin), where sediments carried by erosion rusty brown mixture of hermatite accumulate & turn into sedimentary rocks & goethite Diffusion – atoms migrate through a material Hydration – occurs when minerals contained in rocks absorb water Compositional banding – recrystallization produces layers of causing the minerals to expand & different composition that gives the new transformed rock an eventually for the rock to break appearance of bands apart (Minerals which easily expand due to hydration are biotite Heat Atoms in minerals to rearrange themselves into a new crystal & smectite) structure. Under very high Chemical weathering from temperatures, the new organisms – there are microbes metamorphic rock develops compositional banding that obtain compounds from Reaction with hot groundwater Hydrothermal water passing minerals & use the energy from through sedimentary rocks the minerals’ chemical bonds to transform their chemical support their biological processes; composition, resulting in a new there are bacteria that obtain food metamorphic rock 4 EARTH SCIENCE Grade 11 | 1st Semester | Quarter 2 Pressure Pressure compacts/stretches - The major drawback of his work was the absence of a the atoms in minerals, causing compelling mechanism behind the drift a new formation in the mineral - He proposed (1) drift of the centrifugal forces caused by the crystalline structure rotation of the earth (2) gravitational action of the sun & Aquifer – layer of permeable sedimentary rocks (layer of clay) that moon contain or transmit groundwater - Wegener died sometime during the spring of 1930 during a scientific expedition north of Greenland; his body was found Contact with Hot Groundwater – when hot water passes through in May 12, 1931 rocks, it carries dissolved ions & mixes them with others. This changes the chemical composition of rocks. Dissolved ions carried by flowing Continental Drift Theory – proposes that continents had once been hot water precipitate elsewhere where they leave traces of veins. joined & over time had drifted apart (Veins are made from silica) Pangaea – supercontinent that existed between the late Paleozoic & Compositional Banding in Metamorphic Rocks – heat & pressure early Mesozoic eras; began to drift some 175 million years ago cause recrystallization in sedimentary rocks. This causes atoms of the old mineral crystals to rearrange themselves, leading to the formation APPARENT FIT OF CONTINENTS of metamorphic rocks - Von Humboldt noticed that the mountain ranges of Buenos Aires, Argentina match the mountain ranges of South Africa TYPES OF STRESSES ON ROCKS - Continents of South America & Africa are fit together The result of either of the stress is to change the shape of the rock without breaking it; rocks undergo true transformation in temperatures greater than 250 – 300 C (atoms in minerals begin to vibrate only) Normal Stress – rock receives either compression (squeezed) or tension (stretched) Shear Stress – one part of the rock is being pulled in a particular direction relative to the other part METAMORPHIC GRADE Metamorphic Grade – based on the range of pressure & temperature where it is formed FOSSIL CORRELATION - Wegener dug into fossil records of various continents & discovered at least 4 fossils whose distribution suggested that continents used to form one land mass - Glossopteris – a fern whose fossils were found in five continents CONTINENTAL DRIFT THEORY Alfred Wegener (1880 – 1930) introduced his proposition in 1912. He published his ideas in a comprehensive book “The Origins of Continental & Oceans” in 1915 5 EARTH SCIENCE Grade 11 | 1st Semester | Quarter 2 ROCK & MOUNTAIN CORRELATION - Arthur Holmes (British Geologist) who was the first to grasp the significance of thermal convection from the - Same findings were revealed by the rock type & rock earth’s mantle in relation to earth’s crust formation of the mountain ranges in Northern America & - In 1931, he attributed the mechanism for this movement to Europe (Appalachian Mountains & Northwestern Highlands the convection cells in North of Scotland); Santa Catarina Rocks (Brazil) & Karroo - These convection currents moved the earth’s crust, that Strata (South Africa) caused the continents to drift - He published “Principles of Physical Geology” (1944) where he discussed how seafloor spread - The phenomena of spreading seafloor & the resulting collision between the oceanic & continental crusts were the immediate physical forces that caused continents to drift apart PALEOCLIMATE DATA TECHNOLOGY FOR SEAFLOOR MAPPING - Paleo is derived from the Greek palaios, meaning ancient - With the help from Vladimir Kroppen, they plotted ancient Sonar (echo sounding) – by transmitting the seafloor & collecting the desserts, jungles, & ice sheets on paleographic maps traces of echo that came back, scientists were able collect its - They discovered that locations where evidence of ice sheet bathymetric profle once formed were scattered in many continents in their Bathymetric profile – is the seafloor’s cross section which shows present formation ocean depth plotted against location - Glacial Striations – the distinct patterns left on rocks by ice sheets as they slid past the surface of rocks; he found out GPS (Global Positioning System) Satellite – to determine the location that the glacial striations came to have a uniform of something on earth orientation - Tillites – presence of deposits Mid-Ocean Ridges – elongate submarine mountain ranges between 2 – 2.5 km below sea level SEAFLOOR SPREADING Deep – Ocean Trenches – elongate deep areas that lie along the - Became solid proof for the theory of drifting continents perimeter of the Pacific Ocean, & in a few other places; 8 – 12 km deep (deep enough to swallow Mt. Everest) - Sea floor spreads because the oceanic crust underneath it moves in the direction of terrestrial land masses. This Seamount Chains – isolated submarine mountains (used to be active motion is powered by convection currents in the mantle volcanoes). Only one mountain, the one at the end of the chain (active volcano) - When the oceanic crust collides w/ the continental crust Fracture Zones – bands of vertical fractures. They lie parallel to one (subduction zone), continents are bumped from their another & at right angles to mid-ocean ridges places which causes them to move. This produces the apparent drifting motion between continents EVIDENCE FROM PALEOMAGNETISM - Estimated rate of separation between the North American - As magma erupts from oceanic ridges, it become a fresh & Eurasian tectonic plates is 2.5 cm per year supply of material for the seafloor; over time, it solidifies - As it gradually turns into solid rock (molten rock contains CONVECTION CELLS WITHIN THE MANTLE traces of iron which becomes magnetic as well), it acquires magnetic orientation of the magnetic field of our planet (earth is one giant magnet) 6 EARTH SCIENCE Grade 11 | 1st Semester | Quarter 2 - If the seafloor is not spreading, rocks that compose it should Divergent/Spreading Boundary – two plates move apart from each display a uniform magnetic direction. But they do not. other Instead, they display universals in magnetic direction.  Forms rift valley. Over time this rift, which is practically an open Earth’s magnetic field reverses over a long periods of time excavation, can sometimes become a rift lake o The magnetic field reverses because the forces that  Rift (Ridge) – a linear zone where 2 tectonic plates are being pulled generate our magnetic field are constantly changing, apart the field itself is continual flux, its strength waxing &  Ex. Alfagja Rift Valley in Iceland is the rift formed by the diverging waning over time; this causes the location of Earth’s Eurasian & North American Plates magnetic north & south poles to gradually shift every  Convergent Boundary/Convergent Margin – two plates 300,000 years move towards each other; one plate sinking beneath the other Paleomagnetism – study of ancient pole positions; the indisputable physical evidence that sea floor spreads; traces of ancient magnetism preserved in rocks Figure: Paleomagnetism & Spreading sea floor Figure: Paleomagnetism PLATE TECTONICS Plate Tectonics – a theory proposing that earth’s lithosphere consists of distinct plates that move with respect to one another; study of the interlocking plates of earth’s lithosphere Plate Boundary – is where plates meet; friction, sliding, & collision happen along the boundary Subduction Zone – the region along the convergent boundary where Tectonism – deformation of the lithosphere one plate sinks below the other Fault – a fracture in the earth’s crust along which one body of rock is Volcanic Arc – a curving chain of volcanoes that is formed adjacent to displaced by another a convergent plate boundary Fold – a bend/wrinkle of layers of rock as a result of deformation Trench – a deep elongate trough bordering a volcanic arc. It defines the trace of convergent plate boundary Transform/Slide Plate Boundary – plates slide past one another (vertical fault surface); created friction Oceanic-Continental Boundary – form trenches & volcanic arcs; oceanic plates (denser), goes under the continental plate where it  Luzon Transform Fault: Philippine Fault System & the Verde sinks into the subduction zone (the zone where it turned into magma Passage – Sibuyan Sea Fault; 5.4 magnitude earthquake w/ 60 due to the intense heat from the asthenosphere) aftershocks that struck Batangas (April, 2017) 7 EARTH SCIENCE Grade 11 | 1st Semester | Quarter 2 Oceanic-Oceanic Boundary – the older plate goes under; the rising CAUSES OF CRUSTAL DEFORMATION magma breaks out of the plate above where it forms a volcanic arc Confining Pressure – pressure caused by a load of overlying rocks  Sea Mounts – a volcanic arc when under sea level & when no longer active Stress along plate boundaries – pressure exerted by crustal plates to  Volcanic Island Arc – when it rises above sea level, it forms a chain each other along plate boundaries of islands o Ex. The island chains of Mariana in the South DEFORMATION OF EARTH’S CRUST Pacific Folding – curved or bent as a result of forces acting on them Faulting – a fracture or break as a result of displacement of one part of a rock in relation to the other  Fault Blocks – large masses of rock  Uplift – rising of a part of earth’s crust to higher elevation  Subsidence – sinking of a part of earth’s crust to lower elevation Mountain Building – rock layers are squeezed & pushed upward as a result of compression & uplift Continental-Continental Boundary – two converging continental Mountain Range – chain of mountains (Converging Plates) plates Trenches – long narrow steep-sided depression in the ocean  Ex. Himalaya Mountain Range (2900 km (diverging/converging plates) long) o About 80 million years ago India was Volcanoes – vents in earth’s crust caused by the eruptions of molten located roughly 6400 km south of the Asian rock, hot rock fragments, & hot gases continent but was moving northward at a rate of 900 cm per 100 years. When it collided w/  Volcanic Mountains – formed by repeated eruption & the Eurasian plate it caused intense folding & faulting, shallow earthquakes, &the shortening accumulation of lava & thickening of the plates Valleys – elongate depression on the earth’s surface DEFORMATION OF EARTH’S CRUST  Rift Valley – formed by diverging plates Deformation – change in shape, volume, & position of rocks because of forces applied to them FORCES ACTING ON ROCKS Compression – force that squeezes the rock resulting in a decreased volume Tension – force that stretches the rock resulting in an increased volume Shear – force that acts on the rock in opposite directions resulting in a change in shape 8