ETEEAP 2019-2020 Earth Science Topics vTheories on the Origin of the Universe vTheories on the Origin of the Solar System vEarth Structure and Subsystem vEarth’s Materials and Processes vExogenic Processes vEndogenic Processes Earth: History and Geologic Time § Based from the information gathered from the: Ø study of rock’s composition and structure (PETROLOGY), Ø rock layer (STRATGRAPHY) Ø Fossils (PALEONTOLOGY) § Geologists developed the GEOLOGIC TIME SCALE Ø It represents the interval of time occupied by the geologic history of Earth. Ø It provides a meaningful time frame within which events of the geologic past are arranged. Fossils Ø are evidences of organisms that lived The Evidence in the past. of Past Life Ø They can be actual remains like bones, teeth, shells, leaves, seeds, spores or traces of past activities such as animal burrows, nests and dinosaur footprints or even the ripples created on a prehistoric shore. Ø In exceptional preservation, fine details such as original color and individual muscle fibers are retained, features often visible in electron microscopes. Ø This is referred to as the “Medusa effect.” TYPES OF FOSSILS DESCRIPTION EXAMPLE Molds Impression made in a substrate = negative image of an organism Shells Casts When a mold is filled in Bones and teeth Petrified Original Remains Carbon Film Trace / Ichnofossils Organic material converted into stone is Preserved wholly (frozen in ice, trapped in tar pits, dried/ desiccated inside caves in arid regions or encased in amber/ fossilized resin) Carbon impression sedimentary rocks in Record the movements and behaviors of the organism Petrified trees; Coal balls (fossilized plants and their tissues, in round ball shape) Woolly mammoth; Amber from the Baltic Sea region Leaf impression on the rock Trackways, toothmarks, gizzard rocks, coprolites (fossilized dungs), burrows and nests Petrified Carbon Film Original Remains Trace / Ichnofossils Fossils: The Evidence of Past Life Principle of Succession Øformulated based on the observation of William Smith, an English Engineer and Canal builder. ØHe discovered that each rock formation in the canal he worked on contained fossils and noted that sedimentary strata could be identified and correlated by their fossil content. ØIt states that fossil organisms succeed one another in a definite and determinable order and, therefore, any time period can be recognized by its fossil content. Fossils: The Evidence of Past Life Principle of Succession Ø Paleontologist recognized an age of Fusion, Age of Reptiles, and an Age of Mammals, among others. Ø These ages pertains to groups that are plentiful and characteristics of a particular period. Ø Once the fossils are recognized as time indicators, they are now used in correlating rocks of similar age in different regions. Index Fossils Ø Fossils that are considered as time indicator Ø Fossils that are associated with a particular span of geologic time. Refer to the figure. Which fossil (a, b, c, d,) is considered on index fossil? Why? Item (a) is the index because it is associated with a span of geologic time. DATING FOSSILS Ø Ways to measure the age of a fossil: 1. RELATIVE DATING 2. ABSOLUTE DATING Earth: History and Geologic Time DATING FOSSILS 1.RELATIVE DATING ØBased upon the study of layer of rocks ØDoes not tell the exact age: only compare fossils as older or younger, depends on their position in rock layer ØFossils in the uppermost rock layer/ strata are younger while those in the lowermost deposition are oldest Earth: History and Geologic Time DATING FOSSILS How Relative Age is Determined A. Law of Superposition: Ø if a layer of rock is undisturbed, the fossils found on upper layers are younger than those found in lower layers of rocks Ø However, because the Earth is active, rocks move and may disturb the layer making this process not highly accurate Earth: History and Geologic Time How Relative Age is Determined B. LAW OF ORIGINAL HORIZONTALITY: Ø The law states that layers of sediment were originally deposited horizontally under the action of gravity. Ø Any rock layers that are now folded and tilted have since been altered by later outside forces. Earth: History and Geologic Time DATING FOSSILS How Relative Age is Determined C. LAW OF CROSS-CUTTING RELATIONSHIPS Ø If an igneous intrusion or a fault cuts through existing rocks, the intrusion/fault is YOUNGER than the rock it cuts through Earth: History and Geologic Time DATING FOSSILS 2. ABSOLUTE DATING ØDetermines the actual age of the fossil ØThrough radiometric dating, using radioactive isotopes carbon-14 and potassium-40 ØConsiders the half-life or the time it takes for half of the atoms of the radioactive element to decay ØThe decay products of radioactive isotopes are stable atoms. Ø Take a look at the table Ø A living organism has carbon-14. Ø For the amount of Carbon in the organism’s body to become half, it will take about 5,700 years; which is the half-life of carbon-14. Ø Fill up the remaining data in the table. Ø What is the limit in using carbon-14 as a measure to determine a fossil’s age? Half Life Mass of original C-14 remaining (g) Number of years 0 1 2 3 4 5 6 1 0 ½ 5,700 ¼ 11,400 1/8 17,100 22,800 1/16 1/32 1/64 28,500 34,200 A Brief Description of Earth’s History ØThe system of naming the period has been constantly changing. ØPaleogene and Neogene were suggested instead of Tertiary and Quaternary period. ØThere has been debate about changing the name, eventually the matter was settled and the old name was kept. Era Traditional Period Quarternary New Period Epochs Holocene Neogene Pleistocene Pliocene Cenozoic Era Miocene Tertiary Paleogene Oligocene Eocene Paleocene A Brief Description of Earth’s History Geologists divided the 4.6 Gya of Earth’s history into different units § § § § Eon Era Period Epoch A Brief Description of Earth’s History Precambrian § Comprises about 88% or a total span of roughly 4.1 Ga § Hadean § “chaotic ion” § 4.6 to 3.8 Gya § Earth surface was continually bombarded by meteorites and the very hot mantle caused severe volcanism § Earth would look very inhospitable. § Ocean and atmosphere were formed, and the core, as well as the crust, were stabilized. A Brief Description of Earth’s History Precambrian § Archean § 3.8 to 2.5 Gya and lasted for 1.3 Ga § The Earth was probably warm § The atmosphere contained mostly methane and little to no oxygen. § Most of the Earth was covered with ocean. § Continent formation began during this time. § There was a profusion of volcanoes, § the sky was orange due to abundance of methane, § the sea was green because of iron, § the shoreline were marked with stromatolites. A Brief Description of Earth’s History Precambrian § Proterozoic § 2.5 Gya to 542 Mya and lasted for 1.9 Ga § The longest period that lasted almost half the age of the Earth. § It was the time of great changes: a. oxygenation of the atmosphere, b. origin and diversification of eukaryote life, c. appearance of multicellular animal life and d. motion of the continental drift. A Brief Description of Earth’s History Phanerozoic Ion § It consists of three eras: § Paleozoic § Mesozoic § Cenozoic Paleozoic Era § May fossils were found in layers of sedimentary rocks § Marine invertebrates probably lived near the shores of shallow water. § Fossils of trilobites and brachiopods were found preserved in rocks § Marine life form had developed shells (middle Paleozoic era) A Brief Description of Earth’s History Phanerozoic Ion Paleozoic Era § § § § § § § § § The first animal to succeed in adapting itself to breathe air was an amphibian that came out of the sea during the Devonian period. Land plants also began to developed Giant ferns and marsh plants provided food to land animals which increased in numbers. Marine life also developed. Clams and snails increased in numbers. Fish become more abundant and showed greater variety. Late Paleozoic era showed the appearance of reptiles Toward the end of this era, the land climate change. Many kinds of plants, such as land fern, grew during this era. Scientists believed that the remains of these plants formed the huge coal deposits in many parts of the world. Phanerozoic Ion Mesozoic Era § § § § § § The early part of this era saw the formation of several continents. North America began to part from Europe and probably, South America and Africa began to drift apart as well. At the end of this era, Australia, New Zealand, and India had left Africa, though Arabia still remained attached. With the formation of continents, new bodies of water were formed. Great changes in plants and animal life occurred. Scientists have found footprints, bones, eggs and other fossils of reptiles which existed during this era. Dinosaurs was the largest creatures existed during this era and were believed to be the descendants of the primitives reptiles that had survived during the Paleozoic era. § However, current theory suggest that they were ancestors of birds. Phanerozoic Ion Mesozoic Era § § § § § § The early part of this era saw the formation of several continents. North America began to part from Europe and probably, South America and Africa began to drift apart as well. At the end of this era, Australia, New Zealand, and India had left Africa, though Arabia still remained attached. With the formation of continents, new bodies of water were formed. Great changes in plants and animal life occurred. Scientists have found footprints, bones, eggs and other fossils of reptiles which existed during this era. Dinosaurs was the largest creatures existed during this era and were believed to be the descendants of the primitives reptiles that had survived during the Paleozoic era. § However, current theory suggest that they were ancestors of birds. A Brief Description of Earth’s History Phanerozoic Ion Mesozoic Era § Toward the end of this era, more continents broke up. § North and South America, Australia, Africa, and India became separate plates. § The plates drifted north and south until they reached their present position. § Reptiles were the first true terrestrial vertebrates existed which flourished during this era. § Many reptiles groups became extinct. § The only surviving reptiles today are turtles, snakes, crocodiles, and lizards. A Brief Description of Earth’s History Phanerozoic Ion Cenozoic Era § § § § § § § During this era, mountains were uplifted and new life forms started appearing. Volcanic activity was also widespread, forming immense flow of lava and basalt. Warm-blooded animals such as kangaroo and primitive mammals roamed the land. Fossils during this era showed mammals with tooth structures for specific diets, limb structures for various postures, and increased brain size. This era also shared the development of the modern horse, modern birds and deciduous trees. Toward the end of this era, glaciers covered the Northern Hemisphere. During this period, humans left their marks on land, the earliest records were stone tools. Earth: Structure and Subsystems Formation of Earth’s Layers ØThe beginning stages of Earth’s life were violent. ØIt was under continuous bombardment by meteorites and comets ØThese bombardment helped shape the Earth and brought water in the form of ice. ØThese bombardment also enriched the Earth with carbon dioxide, methane, nitrogen, and ammonia. ØAt First, the Earth was extremely hot and much larger that it is now. Earth: Structure and Subsystems Formation of Earth’s Layers ØThe Earth was made of rocks, different compounds, and dense elements, like solid and liquid iron. ØAs Earth cooled and contracted, the heavier materials moved to the center of the Earth to form the Core. ØThe liquid materials settled over the core to form the Mantle. ØAs the Earth cooled more, a solid Crust formed over the liquid middle. Layers of the Earth The study of Earth’s interior is the most difficult because it is inaccessible. The information about Earth’s core is from seismic information and computer models. Core: Inner and Outer Inner Core § It has a radius of 1250 km § Consists mainly of iron-nickel alloy and is magnetic § It has a temperature of about 6,000 "πΆ, almost as hot as the surface of the sun § The pressure in the inner core is so great that alloy cannot melt § For this reason, inner core is mostly solid Core: Inner and Outer Outer Core § § § § Made mostly of iron and nickel Approximately 2300 km thick The temperature ranges from 4,000 "πΆ to 5,000 "πΆ Because of the very high temperature and the presence of radioactive elements, the outer core is liquid. The Earth’s molten metallic core give rise to magnetic field. The magnetic field is attributed to the dynamo effect of circulating electric current. Inner and Outer Core Inner Core Outer Core Iron and Nickel Iron and Nickel Magnetic Magnetic Solid Liquid 1250 km 2,300 km Cause of Earth’s Magnetic Field Mantle: Lower and Upper § The largest part of the Earth § Intermediate layer of Earth and is divided into Lower and Upper mantle § It is made up of molten rocks called magma. § Magma circulates in current determined by • the cooling and sinking of heavier minerals • Heating and rising of the lighter minerals § It has a total thickness of 2,900 km Mantle: Lower and Upper Lower Mantle § Hot and exhibit plasticity § High pressure in this layer causes formation of minerals that are different from that of the lower layer § Gutenberg discontinuity is detected between Earth’s lower mantle and the outer core. § It is 2240 km thick Mantle: Lower and Upper Upper Mantle § Mohorovicic discontinuity is the upper boundary that separates the upper mantle from the Earth’s crust. § Moho is 5 to 10 km below the ocean floor and 20 to 90 km with an average of 35km beneath typical continents. § Asthenosphere is the layer that lies after the lithosphere (100 km to 250 km) beneath Earth’s surface. § The balance between temperature and pressure is so great that the rocks have little strength (weak) and are easily deformed. § It is believed that asthenosphere plays a critical role in the movement of plates on surface of Earth according to the plate tectonic theory. Lower and Upper Mantle Lower /Mid-Mantle Upper Mantle Asthenosphere Lithosphere Soft / magma Rigid / Solid Exhibits “plasticity” Moho boundary Convection Current 660 km 2240 km Crust: Continental and Oceanic § Two types of crust that make up the surface of the lithosphere: § Continental crust § Oceanic crust § Both lies on the top of the mantle. § Continental crust is relatively thicker than the oceanic crust because of higher elevation. Crust: Continental and Oceanic Oceanic Crust Continental Crust Dark-colored Light-colored Basaltic Granitic More dense Less dense Thin layer Thick layer 50 km 40 – 70 km km Earth’s Subsystems § Our planet is dynamic, and each part (land, water, air, and life) are interconnected and continuously interact with one another. § The interacting parts in Earth’s system are called Subsystems § Four subsystems of Earth § Lithosphere § Atmosphere § Hydrosphere § Biosphere Earth’s Subsystems § Lithosphere § the solid outer section of Earth. § it includes the entire crust and the rigid upper mantle (continental and oceanic crust) § it is not a continuous layer § it is divided into a number of huge plates that move in relation to one another. Earth’s Subsystems -Lithosphere § It is believed that at the beginning, the continents are all locked up into a huge landmass called Pangaea (Alfred Wegener) § They broke apart and gradually drifted to their present position. § Plates drift sideways at the rate of 12 cm per year Earth’s Subsystems -Lithosphere § The large scale movement of Earth’s plate is explained by the Plate Tectonic Theory. § The theory proposes that the lithosphere is divided into major plates and smaller plates resting upon the lower soft layer called Asthenosphere. § The mechanism of movement is probably related to the convection current within the mantle. § There are 15 major tectonic plates, however, experts today count more than 50 plates The 15 Major Plates The Philippine plate which the Philippines rests on has been renamed to Philippine Sea Plate Earth’s Subsystems -Lithosphere § The boundary between tectonic plates is called Boundary. § Each tectonic plate moves in a different direction. § Because of these differences, the tectonic boundaries are grouped into: § Convergent § Divergent § Transform The tectonic boundaries Divergent Boundaries The tectonic boundaries The tectonic boundaries Tectonic Boundaries Map Earth’s Subsystems § Atmosphere § The early Earth is very different from what Earth is today. § The early Earth had a atmosphere that was very inhospitable. § It is characterized be frequent asteroid and meteorite bombardment as well as frequent volcanic eruptions. § The temperature is very high, causing Hydrogen (π»$ ) and Helium (He) to escape into outer space. § The early atmosphere has lots of water vapor but no oxygen. Earth’s Subsystems § Atmosphere § Frequent volcanic eruption produced water (π»$ O) and gases, such as carbon dioxide (πΆπ$), carbon monoxide (CO), sulfur dioxide (ππ$), nitrogen (π$ ), ammonia (ππ»( ), and methane (Cπ»( ), but still no oxygen. § As Earth cooled, water (π»$ O) condensed to form ocean, carbon dioxide (πΆπ$) dissolved into oceans forming carbonates and nitrogen (π$ ), became a major components of the atmosphere. Earth’s Subsystems § Atmosphere § Two component processes changed Earth’s atmosphere: 1. The radiation from the sun o It caused water (π»$ O) to split: o Hydrogen (π»$ ) escaped into outer space and oxygen ( π$ ) accumulated in the atmosphere. Earth’s Subsystems § Atmosphere § Two component atmosphere: processes changed Earth’s 2. A type of organism called Cyanobacteria o It evolved and began carrying out photosynthesis. o Photosynthesis utilized carbon dioxide (πΆπ$ ) and energy to produce sugar and oxygen o . o The oxygen ( π$ ) released during photosynthesis became the main source of oxygen in the atmosphere Earth’s Subsystems § Atmosphere o The development, evolution and growth of life increased the quantity of oxygen in the atmosphere. o Since, there was enough oxygen in the atmosphere, ozone ( π) ) layer protected terrestrial life from ultraviolet radiation. o As a result terrestrial life developed and flourished. Earth’s Subsystems § Atmosphere § At present, the Earth’s atmosphere is mainly composed of nitrogen and oxygen with trace amounts of several gases. Earth’s Subsystems § Atmosphere § It is divided into several layers based on temperature, and separated by boundaries (“pauses’) Earth’s Subsystems § Hydrosphere § Nearly 71% of Earth’s surface is covered by ocean. § World’s ocean are divided into five main ocean basins: § Pacific Ocean § Atlantic Ocean § Indian Ocean § Arctic Ocean § Antarctic Ocean Earth’s Subsystems § Hydrosphere § Composition of the Hydrosphere § Saltwater or seawater has an average salinity of 3.5%. § Salinity refers to the proportion of dissolved salt to pure water expressed in parts per thousand (ppt). § The amount may seem small but the actual quantity is huge. § If all the water in the ocean were evaporates, a 60-m layer of salt would cover the entire ocean floor. Earth’s Subsystems § Hydrosphere § Composition Hydrosphere of the § Salt water accounts for 97.5% of water on Earth’s crust. § This comes from ocean and midland seas § Of the available fresh water: § 68.9% is locked in glaciers § 30.8 % exists as groundwater § 0.3% is easily accessible in lakes and river systems § Of the 2.5% available freshwater on Earth, only about 30% is accessible. Earth’s Subsystems § Ocean Zones § A. Horizontal Zones Coastal Zone § is the region in which the sea bottom is exposed during low tide and is covered during high tide. Pelagic Zone § is located seaward of the coastal zone’s low tide mark. Always covered with water. § Divided into: § Oceanic Zone – lies above the continental shelf. It begins from the low tide mark outward from the seashore and extends to a depth of 200 m. Sunlight penetrates the water. § Neritic Zones - Extends from the edge of the continental shelf, over the continental shelf and over the ocean floor. It is characterized by zero visibility. Earth’s Subsystems § Ocean Zones § A. Vertical Zones § Divide the ocean based on depth, beginning at sea level to the deepest point of the ocean. Earth’s Subsystems § Biosphere § § § § Contains the entirety of Earth’s living things. Also referred to as the “zone of life” It is divided into Biomes (world’s major communities) The Five Major Biomes § Aquatic § Includes freshwater and marine biomes. § Forest § Includes tropical, temperate, and boreal forest, as well as Taiga § Desert § Characterized by low rainfall (less than 50 cm/year) § Tundra § The coldest of all Biome § Grassland § areas with hot, dry atmospheres Earth’s Materials § Rocks Classification of Rocks § Igneous Rocks § Sedimentary Rocks § Metamorphic Rocks Earth’s Materials § Igneous Rocks § From the Latin word ignis, meaning “fire” § Forms when magma or lava cools and harden § Lava- outside the Earth’s crust § Magma – inside the Earth’s crust § Classified according to: § Where they are made § The texture of the rock § What they are made of Igneous Rocks: Where they are made? Outside Earth: Extrusive Igneous Rocks § What cools? Magma or Lava? Lava Inside Earth: Intrusive Igneous Rocks § What cools? Magma or Lava? Magma Earth’s Materials Igneous Rocks § Igneous rocks may be characterized by their texture and composition: § Texture – it describes the overall appearance of the igneous rocks based on the size, shape, and arrangement of their interlocking crystals. § Coarse-grained – grains of crystals can be seen with bare eyes. § Medium-grained – grains of crystals only be seen through a hand lens. § Fine-grained – grains of crystals can only be seen through the microscope. How do we get big crystals? Slow cooling inside Earth How do crystals? we get small Quick cooling outside Earth What could have caused this? These rocks experienced two cooling situations. Earth’s Materials § Sedimentary Rocks § The process by which sediments are transformed into solid sedimentary rocks is called Lithification § it has a particular importance to Earth’s history. § fossils are only found in sedimentary rocks Earth’s Materials Types of Sedimentary Rocks § Clastic Sedimentary Rocks § Rocks is made up of rocks fragments that have been moved by wind, water or ice. § Chemical Sedimentary Rocks § Forms from mineral that precipitate from water. § Organic Sedimentary Rocks § Forms from the remains of organisms. Earth’s Materials § Classification of Sedimentary Rocks Classification of Sedimentary Rocks Based on Particle Size Particle Size Sediments Coarse Gravel (rounded, angular particle) Medium Fine Very Fine Sand Mud Mud Rocks Conglomerate Breccia Sandstone Siltstone Shale Earth’s Materials § Classification of Sedimentary Based on Chemical Composition Composition Calcite (CaCO) ) Quartz (SiO$) Rock Name Limestone coquina Fossil ferrous Biochemical Limestone Limestone chalk Chert Flint Gypsum (CaSO( 2H$ O) Rock Gypsum Halite (NaCl) Rock salt Plant fragments Bituminous rock Rocks Earth’s Materials § Metamorphic Rocks § Came from preexisting rocks called parent rock § The preexisting rock undergo changes in the mineralogy, texture, and chemical composition by the action of heat, pressure (stress), and chemical agents. § The process is called Metamorphism. Earth’s Materials § Types of Metamorphism § Regional § Caused by high temperature and pressure in large regions of the Earth’s crust. § Can range from high to low grade § Changes in minerals and rock types § Folding and deforming of rock layers. Earth’s Materials § Types of Metamorphism § Contact § When molten materials comes in contact with solid rocks. § High temperature. § High to low pressure § Metamorphic effects decrease with distance. Earth’s Materials § Types of Metamorphism § Hydrothermal § When very hot water interacts with rock § Original texture and mineral composition can change § Ore of gold, copper, zinc, tungsten, and lead form in this way. Earth’s Materials Metamorphic Textures Foliation – the arrangement of minerals into planes. A. Foliated metamorphic rocks § layered or banded appearance that is produced by exposure to heat and directed pressure. B. Non-foliated metamorphic rocks § do not have a layered or banded appearance Types of Foliation Compressional Layering Preferred orientation of platy minerals in matrix without proffered orientation Preferred orientation of platy minerals Preferred orientation of lenticular minerals aggregates. Shape of deformed grain Preferred orientation of fractures Grain size variation Combination of the above Common Metamorphic Rocks Rock Name Description Parent Rock Slate Foliated, fine grained Gneiss Foliated, medium to coarse-grained Marble nonfoliated, medium to coarse-grained Shale Granite Volcanic rock Limestone Picture The Rock Cycle Earth’s Materials Minerals § Characteristics of Minerals § Naturally occurring: formed by processes on or inside Earth without input from humans. § Inorganic: not made by life processes. § Element or compound with a definite chemical composition. § Orderly arrangement of atoms; all minerals are crystalline. Earth’s Materials Minerals Mineral Crystals § Crystal: solid with atoms arranged orderly, repeating patterns. § Some crystals form from magma, hot melted rock below the Earth’s surface. § When magma cools slowly, crystals are large. § When magma cools quickly, crystals are small. § Crystals can form from solutions as water evaporates or if too much of a substance is dissolved in water. Physical Properties of Minerals 1. Crystal Structure Physical Properties of Minerals 2. Crystal Habit Acicular Needlelike Dendritic Plantlike Reniform Kidney Shape Prismatic Elongated in one direction Tabular Broad and flat Physical Properties of Minerals 3. Hardness § Mineral’s resistance to scratch. § Depends on the chemical composition and the crystalline structure of a mineral § Mohs scale of hardness – the most common scale of measurement used. Physical Properties of Minerals 4. Color and Streak Streak – refers to the color of a mineral in powdered form Physical Properties of Minerals 5. Transparency § Mineral is transparent if it allows the light to pass through and you can see objects through § Mineral is opaque if light cannot pass through and you cannot see object through it § Mineral is translucent if it allows light to pass through and objects cannot be clearly seen through it Physical Properties of Minerals 6. Cleavage § It refers to the mineral’s resistance to being broken. § It describes how a mineral breaks along weakness plain. § The quantity of cleavage can be described in how clearly or easily the minerals break, like perfect, good, distinct, poor, or indistinct. Physical Properties of Minerals 7. Luster Luster – indicates how light is reflected off a surface of a mineral Physical Properties of Minerals 8. Specific Gravity § It describes the mineral’s density in comparison to the density of a standard like water. § It can be determine using a balance Earth’s Processes Exogenic Processes § occur at or near the surface of Earth § part of the rock cycle. § responsible for transforming rock into sediments § includes degradation processes like: Weathering, Mass wasting, Erosion transportation § also includes aggradation processes like deposition Earth’s Processes Exogenic Processes 1. Weathering § Physical breakdown and / or chemical alteration of rocks at or near Earth’s surface § It is a degradation process that does not involved movement of materials § Types of Weathering: A. Mechanical Weathering B. Chemical Weathering Earth’s Processes Exogenic Processes 1. Weathering A. Mechanical Weathering or Disintegration § the breaking up of large rocks into smaller fragments without changing the rock’s mineral composition. § Physical that occur in nature that break rocks into smaller pieces a. Frost wedging b. Insolation weathering or thermal stress c. Unloading or pressure release Earth’s Processes Exogenic Processes 1. Weathering B. Chemical Weathering § § the rocks decomposes through chemical change. The process involved are: a. Oxidation – oxygen dissolved in water. - Reddish-brown rust will appear on the surface of iron- rich minerals which easily crumbles and weakens the rocks b. Hydrolysis - It affects rocks containing silicates - water dissolves silicates in the rocks c. carbonation and solution - carbon dioxide dissolved in water forming carbonic acid that will react with carbonic rocks d. Biological Action - interaction of some plants and animals Earth’s Processes Exogenic Processes 2. Mass Wasting § The mass movement of rocks, soil, and regolith § Gravity is the driving force of mass wasting. Types of Mass Wasting a. b. c. Rock and Debris Falls • Rock fall occur when pieces of rocks or mass of rocks dislodged and makes free-fall along a steep cliff. • Debris fall occurs when mixture of soil regolith, vegetation and rocks makes free-fall along a steep slope. Landslides • Translational slides involve the movement of mass of materials along a well-defined surface. • Rotational slides occurs when the descending materials move in mass along concave, upward curved surface. Flows • Slurry flows consists of mixture of rocks or regolith 20% and 40% water • Granular flows contain 0 to 20% water Earth’s Processes Exogenic Processes 3. Erosion and Transportation Process of transporting weathered sediments by agents of erosion to different places. Agents of Erosion A. Water B. Glaciers C. Wind Different Types of Water Erosion a. Splash Erosion b. Sheet Erosion c. Gully Erosion d. Valley Erosion e. Bank Erosion f. Coastline erosion g. Seaside Erosion Earth’s Processes Exogenic Processes Transportation § Materials are transported in four different ways: a. Solution – Materials dissolved in water and crried along by water. b. Suspension – the suspended particles are carried by a medium like air water, or ice. c. Traction – particles move by rolling, sliding and shuffling along eroded surface. d. Saltation – particles move from the surface to the medium in quick repeated cycles. The repeated cycle has enough force to detach new particles. Earth’s Processes Exogenic Processes 4. Deposition and Depositional Landforms It is the aggradation or accumulation of weathered sediments to create different landforms. Water and Landforms § Alluvium- materials (sand, mud, gravel, etc.) deposit of stream. § Deltas § Alluvial fans § Flood plain § Levees Earth’s Processes Exogenic Processes 4. Deposition and Depositional Landforms Glaciers and Landforms § Glacial till § Moraines § Esker § Drumlins Winding ridges of sand and gravel deposited under a glaciers by water melting from the ice. Unsorted deposits of rocks Streamlined asymmetrical hill composed of till Layers or ridges of till Earth’s Processes Exogenic Processes 4. Deposition and Depositional Landforms Wind and Landforms § Loess § Sand Dunes Deposits of coarse materials in the shape of hill or ridges. Accumulated blanket of silt carried by wind in suspension and deposited over broad areas Earth’s Processes Endogenic Processes - changes that shape the landscape of the Earth that is internal in nature. - Some important endogenic processes are a. tectonic processes - folding - faulting - shearing b. volcanism Earth’s Processes Endogenic Processes Tectonic Processes: Theories and Plate Boundaries Tectonic § the study of the processes that deform Earth’s crust. Continental Drift § Proposed by Alfred Wegener § Suggested that continents were all originally part of a huge landmass called Pangaea that was surrounded by a single ocean, Panthalassa. Earth’s Processes Endogenic Processes Continental Drift § Few hundred million years ago, Pangaea was supposed to have begun to break up and the continents slowly drifted to their present location. Earth’s Processes Endogenic Processes Evidences of Continental Drift 1. Locations of Past Glaciations. The deposits of glacial debris and fossil remains of certain plant species in Argentina, Brazil, South Africa, India, and Australia follow each other in the same succession. Earth’s Processes Endogenic Processes Evidences of Continental Drift 2. The Distribution of Climatic Belts. 3. The Distribution of Fossils Earth’s Processes Endogenic Processes Evidences of Continental Drift 4. Matching Geologic Units Earth’s Processes Endogenic Processes Evidences of Continental Drift 5. The Fit of the Continents Earth’s Processes Endogenic Processes Plate Tectonic Theory § § § § Proposed that the lithosphere consists of seven large segments and numerous smaller ones called Plates. The Plates rest upon the soft layer of Asthenosphere. The plates move relative to each other. The driving force for plate movement is the convection flow, in which warm buoyant rocks rise and cooler material sink. Earth’s Processes Endogenic Processes Evidence of Plate Tectonic Theory 1. Paleomagnetism § The study of the fossil (especially rocks) formed millions of years ago that contain records of the direction of the magnetic poles at the time of their formation. Earth’s Processes Endogenic Processes Evidence of Plate Tectonic Theory 1. Distribution of Earthquakes § Earthquake often occurs along faults. § Faults are break in a rocks mass where plate movement has occurred. § Faults are associated with plate boundaries Earth’s Processes Endogenic Processes Plate Tectonic Theory Plate Boundaries § A fracture separating one plate from another. § Three distinct types of boundaries: § Convergent boundary § Divergent boundary § Transform fault boundary. Earth’s Processes Endogenic Processes Plate Boundaries 1. Convergent Boundary § Occurs when two plates move toward each other § Crust is destroyed when two plates converge. § The heavier plates dives (subducts) beneath the more buoyant plate. Earth’s Processes Endogenic Processes Plate Boundaries 1. Convergent Boundary § Subduction zones of Convergent boundary: § Oceanic-continental convergence § Forms trenches, destructive earthquakes, and rapid uplift of mountain ranges, as well as the building of volcanic arc. § Oceanic-oceanic convergence § Also forms trenches (Marianas trench) and volcanic arc. § Continentalcontinental convergence § Forms mountain range like the Himalayan range. Earth’s Processes Endogenic Processes Plate Boundaries 2. Divergent Boundary § Occurs when two plates move away. § Most divergent boundaries occurs along the crest of oceanic ridges. § When two plates move apart, there is upwelling of magma from the hot mantle. § As the magma cools, new seafloor is created called Sea floor Spreading. § The spreading is too slow about 3 to 10 cm a year Earth’s Processes Endogenic Processes Plate Boundaries 3. Transform Boundary § Occurs when plates slide horizontally past one another. § Most transform faults occur within the ocean basin, but there are a few that can be found in continental plates.. Earth’s Processes Endogenic Processes Tectonic Forces and Processes § § When rocks are subjected to stresses (tectonic process) they begin to deform. They deform by folding and faulting Folding Ø or folds occurs when rocks are pushed towards each other from opposite sides Ø The rock layers bend into folds Ø Folds are produced by horizontal compressive stresses, such as continent-continent collisions or collisions at any convergent boundary. Earth’s Processes Endogenic Processes Tectonic Forces and Processes Faulting Ø The fracturing and displacement of brittle rock strata along a fault plane. Faults Ø Are fractures along the crust in which displacement has occurred. Types of Faults 1. 2. 3. 4. Normal Reverse Sinistral Strike-slip Dextral Strike-slip Earth’s Processes Endogenic Processes Tectonic Forces and Processes Types of Faults Earth’s Processes Endogenic Processes Volcanism § A phenomenon in which materials are erupted from Earth’s interior onto the surface through volcano. Volcano § a vent or a series of vent on the crust § the vent is like chimney, it is where magma, ash, and gases are released. § the mouth of the vent is referred to as crater. § the large almost circular depression formed either by the collapse or explosion of the volcano is caldera. § About 70% of Earth’s volcanic activity occurs along a circle of subduction zones in the Pacific Ocean, called “Ring of Fire”. Earth’s Processes Endogenic Processes Volcanism § Another belt of volcanic activity lies near the convergent margin of the African plate. Volcanic activity is also detected along the Australian plate boundary and is concentrated beneath the ocean. Earth’s Processes Endogenic Processes Magma and other Volcanic Materials § Magma forms in three particular environment: a. subduction zones b. divergent zones c. hot spots or mantle plumes. Earth’s Processes Magma Production at the Subduction Zone due to the following conditions: 1. Increased temperature due to friction. § Friction heats rocks as one plate moves downward. The addition of heat contributes to melting. 2. Addition of water to the Asthenosphere. 3. Pressure-relief melting - Melting due to pressure relief happens when rocks in the asthenosphere flow upward as a subconducting plate descends. Earth’s Processes Volcanic Activity and Prediction Classification of Volcano according to activity (PHIVOLCS) • Active Volcanoes – volcanoes that have erupted within historical time in the last 600 years or having erupted within the last 10,000 years, based on the analysis of datable materials. • Dormant Volcanoes – volcanoes which have not erupted for more than 10,000 years but have the potential to be active again. • Extinct Volcanoes – volcanoes that have not erupted for the last 10,000 years. They are unlikely to erupt again Earth’s Processes Volcanic Activity and Prediction Methods that can be used to predict volcanic activity. 1. Geophysical Methods § Change in slope § Change in elevation § Change in water level and temperature. § Seismic (earthquake activity) § Variation in magnetic field 2. Geochemical Methods § Increased in hydrogen chloride and sulfur dioxide content (hot spring and crater lakes) 3. Remote Sensing (infrared) § Infrared line scanners have been successfully used to determine the future sites of eruption. 4. Abnormal behavior of animals. Earth’s Processes - Earthquake Ø The most common cause of earthquake is Faulting. Ø During faulting, energy is released as the rocks break and move. Ø As they move, they cause nearby rocks to move also. Ø The rocks continue to move this way until the energy is used up. Earth’s Processes - Earthquake Ø Earthquake that occur on the ocean floor cause giant wave called Tsunamis. Ø A tsunami consists of multiple waves that continues for hours after the arrival of the first wave. Ø These waves can travel at speeds of 700km/h to 800km/h. Ø Tsunami is one of the worst natural disaster that can hit a country. Earth’s Processes - Earthquake Ø When earthquake occurs, only a part of a fault is involved in the rupture. Ø That area is usually outlined by the distribution of aftershocks in the sequence. Ø Some faults are deep inside the Earth. Others are close to or at surface. Ø Most faults occurs between the surface and a depth of 74 km. Earth’s Processes - Earthquake Ø Geologists have identified common features of faults and earthquake. Ø One is the focus or the hypocenter, which is the location where the movement or the source of earthquake begins. Ø Earthquake focus can occur at range of depths down to 700 km below the surface. Ø The other feature is the epicenter, which is the geographic location on Earth’s surface directly above the earthquake focus. Earth’s Processes - Earthquake Earthquake waves are known as Seismic Waves. ØSeismic waves are the waves of energy caused by the sudden breaking of rock within Earth or an explosion. Ø They are the energy that travels through Earth and is recorded on Seismographs. Earth’s Processes - Earthquake ØSeismic waves can be distinguish by a number of properties: ØSpeed of the waves travel ØDirection that the particles move as the wave pass by ØWhere they do not propagate. ØThere are three main types of seismic waves, which all move in different ways. ØPrimary waves (p waves) ØSecondary waves (s waves) ØSurface waves (l waves) Earth’s Processes - Earthquake Primary waves or P-wave Øthe fastest seismic waves ØThe first to arrive at a seismic station. ØCan move through solid rock and fluids like water or the liquid layers of earth. ØIt pushes and pulls the rocks as it move ØSometimes animals can hear the P-waves of an earthquake. ØPeople can only feel the bump and rattle of these waves. Earth’s Processes - Earthquake Secondary Wave or S-wave ØSlower than a P-wave. ØThe s-wave stop when they reach the liquid part of the Earth. ØS-wave move rock particles up and down, or side-by-side-perpendicular to the direction the wave is travelling. Earth’s Processes - Earthquake Secondary Wave or S-wave Ø Can only move through solid rock not through liquids or gases. Ø This is the property of s-wave that led seismologists to conclude that Earth’s outer core is a liquid. Ø Because s-wave do not travel through liquids, they are not always recorded at all locations during an earthquake. Earth’s Processes - Earthquake Surface waves or L-wave Ø Earthquake radiates P-and S-waves in all directions and the interaction of the P and S-waves with earth’s surface and shallow structure produces Surface waves or L-waves. Ø L-waves arrive at a certain point after primary and secondary waves. Ø These travel from the focus directly upward to the epicenter. Ø The they mover along Earth’s surface the way waves travel in the ocean. Ø Earth’s surface moves up and down with each L-waves that passes. Ø L waves cause most of the damage during an earthquake because they bend and twist Earth’s surface. Earth’s Processes - Earthquake Earthquake Magnitude and Intensity ØA strong earthquake releases more seismic waves and causes more shaking than small earthquake. ØThe shaking and energy released from different earthquake can be compared using a single standard measure known as Earthquake Magnitude. ØThe location of the earthquake can be determined by at least three seismograph in different locations. ØIts magnitude can be determined from the data on seismograph. Earth’s Processes - Earthquake Earthquake Magnitude and Intensity ØA seismograph is an instrument that detects and measures waves. ØIt consists of a weight attached to a spring or wire. Ø Because weight is not directly attached to the earth, it remains nearly still even when earth moves. Ø A pen attached to the weight records any movement on a sheet of paper wound around a constantly rotating drum. Earth’s Processes - Earthquake Earthquake Magnitude and Intensity Ø Using the seismogram from at least three different places, the epicenter can be located. Earth’s Processes - Earthquake Earthquake Magnitude Intensity and Ø The strength of magnitude of earthquake is measured according to the Richter scale. Ø Richter Scale measures how much energy an earthquake releases by assigning the earthquake a number 1 to 10. Earth’s Processes - Earthquake Earthquake Magnitude and Intensity ØThe intensity of earthquake shaking at a particular location depends on the magnitude of the earthquake, its depth, and its distance from the focus. ØLocal topography, geology, and soils also influence the amount of earthquake shaking. ØThere are variety of intensity scales, but in New Zealand, United States, and Canada, intensity is measured using the Modified Mercalli Intensity Scale. ØThis is a descriptive scale from 1 to 12 based on: a. how people feel an earthquake, b. the damage to buildings and their contents, c. and how the natural environment responds. Thank You!
