Chapter One: Planet Earth PDF

Chapter 1 Planet Earth Session 1 Planet Earth  What is Geology? ▪ Geology is the study of solid Earth, terrestrial planets and moons. It also includes the study of earth’s materials, structures features, resources and history. ▪ The outputs of these studies are applied in eng...

Chapter 1 Planet Earth Session 1 Planet Earth  What is Geology? ▪ Geology is the study of solid Earth, terrestrial planets and moons. It also includes the study of earth’s materials, structures features, resources and history. ▪ The outputs of these studies are applied in engineering, economy, health and risk managements. Planet Earth Geology is the study of the Earth’s materials, ancient organisms, structures and processes affected them. Geologists work to understand the history of our planet. Why?? To foresee (predict) how events and processes of the past might influence the future. Geologists work to understand the earth processes such as (landslides, earthquakes, floods, volcanic eruptions, soil erosion, …) why?? to avoid building important structures where they might be damaged. Geologists work to study the earth’s materials: oil, natural gas, metals, minerals, ores, rocks and groundwater. Also, many geologists are working to learn more about the past climates of the earth and how they have changed across time. Planet Earth  GEOLOGY IN EVERYDAY LIFE Minerals can be found in mobile phones, personal computers, cables, wind turbines, cars, make up, cosmetics, painting, paper and batteries. Groundwater deposits hidden, in the ground, often underneath our feet. Sands, gravels and crushed stone are mostly used to make concrete to build, for example, houses and road. Mineral products surround us in our ordinary daily life and during festive times. Planet Earth  https://youtu.be/QmklVl4IZNQ= 5:33 min. https://youtu.be/zm3YMVWht4c=1:33 min. https://youtu.be/fJUXQvEgfVQ= minute What on Earth does a Geologist Do? https://youtu.be/QSIfIgdWcUs= Planet Earth  History of Earth Science (Geology) There were two main schools of geology: ❖ Catastrophism: (mid 1600s) ▪ Uniformitarianism: (late 1700s) It was based on religious thoughts It states:” The present is the key of as Nuh Flood event. the past”. It is believed that earth landforms James Hutton (1785) supposed that and terrains were formed in short the same processes that are at time due to sudden events. work today were at work in the The catastrophism theory is not past. Therefore, the time is believed anymore nowadays. significant element in earth’s terrains forming processes. Uniformitarianism is a basic foundation of modern geology. Planet Earth  The origin of Earth ❖ Nebular Hypothesis explained how the earth and solar system formed. Nebular Hypothesis supposed that: 1. A large rotating nebula composed of gases and dust existed. This nebula (cloud) shrank according to gravitational force and so started to rotate in faster speed. 2. Most of the mass including heavy parts of this cloud were concentrated in the center and then formed the sun and nucleus of planets. 3. These nucleus grew and formed the planets, meteorites and moons. http://tutribels.blogspot.com/2018/06/origin-of-solar-system.html Planet Earth How old is the Earth? ❖ Although the early geologists recognized that geologic time on Earth is very long, they had no methods to determine the age of the Earth. ❖ The discovery of radioactivity at the beginning of the 20th century allowed geologists to date the rocks accurately and the age of the Earth is estimated to be about 4.6 billion years. Milky Way Galaxy spiral structure Part of the universe and many galaxies. The age of the Our solar system universe is estimated at 14 billion years. Planet Earth How the Earth was formed? ❖ Earth is one of nine (or eight) planets, moons and other smaller bodies orbiting the Sun. ❖ It is believed that most parts of our solar system formed at the same time as the Sun and from the same material. This material formed a vast cloud of dust, ice and gases called the Solar Nebula. ❖ Nebular Hypothesis explains the origin of Sun and planets. ❖ This hypothesis begins with a very large rotating nebula composed mainly of gases hydrogen and helium and with small percentages of heavier elements. Planet Earth How the Earth was formed? ❖ About 5 billion years ago, this huge dusty gas cloud began to contract gravitationally, and the cloud of particles and gas began to rotate faster and faster. This rotation caused the cloud to flatten into a disk. ❖ Most of the nebular material was pulled toward the Centre of this rotating mass to produce the proto-Sun. ❖ By the time of formation of the proto-Sun, the temperature of matter in the nebular disc had dropped to the point where substances with high melting points could condense into small particles, probably the size of the sand grain. ❖ These particles clumped together, producing nuclei that grew by accretion of particles into meteorites, asteroids and comets and finally moons and planets. Planet Earth The Moon and Inner Planets ❖ The Moon and the inner planets (Mercury, Venus and Mars) are similar to the Earth in composition and structure. solid rocky mantle metallic and crust core The Moon Planet Earth The Giant Outer Planets ❖ The giant outer planets (Jupiter, gaseous hydrogen liquid and Saturn, Uranus and Neptune) are metallic hydrogen mainly composed of ice and gas because they formed in the cooler outer parts of the Solar Nebula. outer icy and inner rocky core Jupiter Planet Earth Earth relation to universe https://youtu.be/ x1QTc5YeO6w Planet Earth Identify the inner and outer planets in solar system? Planet Earth Meteorites ❖ Meteorites are “left-over” from the process of accretion. ❖ Their age is the same as the Earth’s age (4.6 billion years). ❖ Meteorites mainly consist of metal (like the Earth’s core) and Mg Fe silicate minerals (like the Earth’s mantle). ❖ Chemical composition is believed to be similar to that of the whole Earth. Planet Earth Session 2 Planet Earth  Let’s focus on Earth! The Earth is composed of several integrated parts (spheres) that interact with one another: Atmosphere Hydrosphere Biosphere (Ecosystem) Solid earth (Lithosphere = Geosphere) Planet Earth  Atmosphere Atmosphere consists of 5 layers, which are from bottom to top: 1. Troposphere: The lowest part of atmosphere and the part we live in. It holds most of our weather. The temperature in the troposphere gets colder as the distance above the earth increases, by about 1°C per 150 meters. 2. Stratosphere: It contains much of the ozone in the atmosphere. The temperature increases upwards, because of absorption of ultraviolet (UV) radiation from the sun by this ozone. 3. Mesosphere: The middle layer of atmosphere. Most meteors burn up in the mesosphere. In the mesosphere the temperatures get colder upward. The CO2 in the mesosphere absorb heat and emit it as photons (Radiative emission). 4. Thermosphere: similar to the stratosphere, the temperature in the thermosphere increases upward. The maximum temperature could reach 2000 °C. The temperature here is affected by solar activity. 5. Exosphere: is the first line of defense against the sun's rays. In the exosphere, the molecules do not collide. Some of the molecules instead are pulled by gravity into lower layers of the atmosphere and some escape into space. Planet Earth  Atmosphere Planet Earth  Atmosphere ❖ The atmosphere consists mainly of Nitrogen gas (75%) and Oxygen gas (25%). ❖ Why is Nitrogen gas important in the atmosphere? If nitrogen disappeared from the atmosphere then humans and animals will be poisoned and will burn to death very soon. Nitrogen is almost unreactive in the atmosphere but it prevents the majority of reactive oxygen from supporting high rates of combustion. Planet Earth  Hydrosphere ❖ Hydrosphere includes all the waters in earth in all their physical states (solid, liquid, gas). ❖ Water distribution on Earth: − Salty water (oceans) is much more than fresh water. − Most of fresh water is frozen (as glacial). Less part is unfrozen. − The unfrozen water includes surface water (rivers, lakes, water vapor in atmosphere, moisture in soil) and Groundwater. Groundwater is more than surface water. Planet Earth Where the Water is? Planet Earth  Biosphere The biosphere is the global sum of all ecosystems. It can also be called the zone of life on Earth, The integration of all living organisms and their relationships, including their interaction with the elements of the lithosphere, geosphere, hydrosphere and atmosphere. Planet Earth  Geosphere (Lithosphere) The lithosphere (geosphere) includes the crust and the uppermost mantle, which constitute the hard and rigid outer layer of the Earth. The lithosphere is underlain by the asthenosphere, the weaker, hotter, and deeper part of the upper mantle. Planet Earth  Solid earth (Lithosphere = Geosphere) ❖ Lithosphere = Crust + Upper mantle. ▪ Crust is the skin of the earth and it is divided into continental crust ❖ Lithosphere is solid (rigid), and it is and oceanic crust. mainly made up of two elements: silicone and oxygen which react ▪ Mantle is beneath the crust and is together and make up silicates. mainly solid, however, it behaves Silicates are the building blocks of like a viscous fluid because quartz mineral (SiO2). temperatures are close to the ❖ Lithosphere is underlined by melting point. asthenosphere. ❖ Asthenosphere is weak and hot. Planet Earth Session 3 Planet Earth  Lithosphere This zone including the mountains, the volcanoes, the deserts, the plateaus and all the geological features on the surface of the earth. Planet Earth  Earth concentric shells Earth consists of: 1- Crust 2- Mantle 3- Core (outer and inner core) https://www.universetoday.com Planet Earth  Earth concentric shells The Earth consists of three concentric shells of rock and metallic materials: ❖ Core: iron, nickel, one third of Earth’ mass − Inner (solid) − Outer (liquid) ❖ Mantle: Over 82% of the Earth's volume is contained in the rocky shell. The mantle is composed of Mg Fe silicate minerals. ❖ Crust: The thin solid outer layer of the Earth and it can be divided into oceanic (3-15 km thick) and continental (10-70 km) thick crust. Rocks of different composition make up the crust Planet Earth  Earth concentric shells: 1- Crust Continental crust Oceanic crust Rock type Granite Basalt Thickness Thicker Thinner (10-70) km (3-15) km Density Less density value More density value Planet Earth  Earth concentric shells: 2- Mantle ❖ Mantle occupies the biggest volume in Earth’s layers. ❖ This layer is responsible of volcanic activities, seismic activities (earthquakes) and tectonics. Earth concentric shells: 3- Core ❖ The Earth’s core is divided into outer and inner core. ❖ The outer core is liquid and the inner core is solid. ❖ The heaviest mineral in earth occurs in the core. ❖ The core is made up mainly of iron and nickel. Planet Earth Session 4 Planet Earth  How do geologists determine the age of an object or event? ❖ Geologic age is divided into two types: 1. Absolute age: expressed in numbers. 2. Relative age: expressed as comparison between more than one object or event, and stated as “older, younger, similar age”. Planet Earth  Absolute age ❖ Method of determining absolute age: unstable (radioactive) isotopes. ❖ This method depends on how much the radioactive isotope decay. ❖ The decay amount determines the age of an object or event numerically. Planet Earth  Absolute age ❖ Isotopes: Elements with the same number of protons and electrons but with different numbers of neutrons in their nucleus. ❖ Half-life: time it takes a radioactive isotope to decay into the daughter isotope by half. ❖ Parent: original unstable isotope. ❖ Daughter: result of decay process. Planet Earth  Relative age ❖ Methods of determining relative age: ❖ Fossils are the main evidence used to determine relative age. 1. Superposition principle: the layers are getting younger upward. This principle could be applied only in undisturbed layers. clarkscience8.weebly.com Planet Earth https://clarkscience8.weebly.com/earths- history-and-diversity-of-life.html  Relative age 2. Faunal succession (Fossils): this method is useful also to correlate widely separated geographically areas (exp. USA & Morocco; UAE, Oman and Egypt). Devonian Trilobites Jurassic Ammonites https://www.uvm.edu Planet Earth  Relative age 3. Secondary structures: a) Cross-cutting: The Principle of Cross-Cutting Relationships states that rock formations that cut across other rocks must be younger than the rocks that they cut across. a) Fold b) Fault Planet Earth https://www.uvm.edu How do geologist express layers of rocks? ▪ Formation: a body of rock with ▪ Contact: surface separating distinguished characteristics two formations. and considerable thickness. ▪ One formation contains rocks with similar rock type and age. http://Wikipedia.org https://blogs.agu.org/mountainbeltway Planet Earth  Simsima Formation Qahlah Formation Qahlah and Simsima formations contact at Jabal Auha, Oman SE NW Rus Formation Dammam Formation Dammam Formation (Lower Eocene) (Middle Eocene) (Middle Eocene) Planet Earth What to choose in determining age (dating)? ▪A typical geological ▪How old is the Earth? study shall include both: absolute age 4.6 billion years old and relative age. Planet Earth  Session 5 Planet Earth  Geologic Timescale The geologic timescale is divided from longest to shortest to: Eon, then Era then Period then Epoch then Age. Parts of Geologic time scale were divided into smaller pieces according to relative and absolute age studies. Tectonics, extinction and appearance of some life forms mark the start and end points of geologic timescale division. https://clarkscience8.weebly.com  Geologic Timescale There are 2 major Eons: 1- Pre-Cambrian Eon: 2- Phanerozoic Eon: It represents more than 80% of It represents less than 20% of Earth’s history which is almost Earth’s history which is almost the first 4 billion years of Earth’ the last 0.6 billion years of age. Earth’ age. It has very few fossils which It marks the start of visible and made the knowledge of the diverse life forms. details of this eon very limited. The first green plant appeared 500 million (0.5 billion) years ago (in the Cambrian Period).  Geologic Time Scale ❖ Precambrian: Vast amount of time, it represents more than 80% of Earth’s history which is almost the first 4 billion years of Earth’ age. It has very few fossils preserved. which made the knowledge of the details of this eon very limited. ❖ Paleozoic Era: “Old Life” – Appearance of complex life; many fossils. ❖ Mesozoic Era “Middle Life" – Dinosaurs were abundant on land. – It ended by mass extinction. ❖ Cenozoic Era: “New Life" – Mammals and birds abundant. – We are currently in the Recent (Holocene) Epoch of Quaternary Period of Cenozoic Era. Most recent ice ages occurred during Pleistocene Epoch of Quaternary Period. Planet Earth Paleozoic Era The Phanerozoic Eon is divided into three Eras called Paleozoic, Mesozoic and Cenozoic. Each Era is further subdivided into Periods, Epochs and Age. Appearance of complex life Existence of multicellular organisms, green plants, invertebrates fishes It ended with rise of Planet Earth amphibians. Mesozoic Era Age of the Middle Dinosaurs were abundant on land This era ended by mass extinction Dinosaurs Age Dominated by large reptiles Planet Earth Cenozoic Era Age of recent life Mammals and birds have been abundant.ammals replaced reptiles We are currently in the Recent (Holocene) Epoch of Quaternary Period of Cenozoic Era. Most recent ice ages occurred during Pleistocene Epoch of Quaternary Period. Planet Earth  ❖ Human first appeared in the Phanerozoic Eon, Cenozoic Era, Quaternary Period, Holocene (Recent) Epoch. ❖Eon- Era- Period- Epoch- Age Planet Earth  Home Work: Write the geological history of the study area ………………………………………………………………………… ………………………………….. ………………………………………………………………………… ………………………………….. the geologic feature which cuts another is the younger Planet Earth The full sequence of events is as follows: Layer C formed, Layer B formed, Layer A formed. When layers A-B-C were presented, intrusion D formed. Intrusion D cut through layers A-C. Fault E formed, shifting rocks A through C and intrusion D. Weathering and erosion occurred, forming a layer of soil on top of layer A. Faulting Erosion of highlands Original rock layers in situ Intrusion Soil development Planet Earth By combining relative dating with absolute dating a history can be made: By combining relative dating with absolute dating a history can be made. Planet Earth  Session 6 Planet Earth Geoscience application in the modern life ❖There are various applications of geology that are linked to human life like: 1. Environmental Geology: It contributes and gives solutions to environmental issues such as pollutions, Johannesburg Mine Water Pollution climatic changes and sea http://www.watersafe.co.za level fluctuations. Planet Earth Geosciences applications in the modern life 2. Engineering Geology: It is an essential part in all the construction projects and natural hazards risk managements. It is significant tool in evaluating material properties and solving A rock sample before and after uniaxial compressive test. problems using geotechnical methods. https://civilblog.org https://www.juniorminingnetwork.com Planet Earth  Engineering Geology: Planet Earth  Geosciences applications in the modern life 3. Geo-archeology: It is the use of geology in finding the historical remaining of human civilization. The geo-archeologists used mainly geophysical tools to look for the ancient ruins. Geophysics give clear results of the location of ruins without distracting the earth’s surface. Example of using geophysical Useful geophysical methods magnetic survey in geo- here might be magnetic archeology in Roskilde city in geophysical method. Also Denmark. radiometric tools could be used in determining the age (date) of http://www.gemsys.ca/wp- content/uploads/2013/04/10_Years_ certain things. of_Overhauser_for_Archaeology.pdf Usually geo-archeologists work within the Holocene beds, where the human have lived. Holocene beds are relatively shallow.  Geosciences applications in the modern life 4. Medical Geology: It finds out the relation of geology (rocks, minerals, groundwater, etc.) to human health.  Geosciences applications in the modern life 5. Forensic Geology: It contributes to the police work and legal issues to find out the correct sequence of certain crime. It uses geophysical tools and the rocks and soil remaining in the criminal. “Dirt on shoes can often tell us more about the Rubber-soled shoes or boots with deep treads are likely activities of the wearer from the first to the last sources for soil specimens. https://makezine.com/ moment.  Collecting soil from the sole of a boot Forensic Geology Lab  Geosciences applications in the modern life 6. Exploration methods: There are two types of explorations: a) Surface exploration: the methods will be mentioned in Chapter 4 and includes in general: field studies, remote sensing and areal photography. b) Subsurface methods: includes direct and indirect methods. The direct methods include direct touch to rock beds by drilling, while the indirect methods give clear image about the resources under the surface without touching them. Indirect methods are mainly geophysical methods, such as seismic (for oil and gas) exploration and electrical (for water exploration). c) Maps: there are three main types of maps. I. First: the topographic maps (give the elevation and height of different locations on the Earth). II. Second: the geochemical maps (shows chemical composition variations in rocks and soil). III. Third: the metallogenic maps (shows the mineral distribution on the earth). Surface exploration (Field studies)  Subsurface indirect Exploration (geophysical methods) Subsurface direct Exploration (drilling) https://www.studentenergy.org/topics/drilling http://www.westgeo.dayborogeo.com/  Geosciences applications in the modern life 7. Earth imaging, Geomatics and geo-informatics: It provides digital colored images of the earth, and links geology to geography. When using this tool, location is needed. Geoinformatics use two types of models: I. Vector model (points, line and area (polygon). II. Raster model (Regular grid of cells, each cell represents an area on the ground). http://www.geo.umass.edu/  End of Chapter 1 Chapter 2: Earth’s Materials Planet Earth