Earth System & Earth Components PDF

Earth System & Earth Components 1 Geology is the study of the Earth. It is concerned with the origin of the Earth, its material and geomorphology, and its history and the internal and external processes that acted (and acts) upon it to affect its historic and present for...

Earth System & Earth Components 1 Geology is the study of the Earth. It is concerned with the origin of the Earth, its material and geomorphology, and its history and the internal and external processes that acted (and acts) upon it to affect its historic and present forms. The term Geology, from the Greek geo and logos, is defined as the study of Earth. The oceans cover more than 70% of the Earth’s Surface 2 Earth composed of: 1- Atmosphere 2- Hydrosphere 3- Lithosphere 4- Biosphere 3 The Earth and its Materials ❖The Earth’s radius is about 6370 kilometers. ❖Most of the Earth is composed of rocks. ❖Rocks are composed of minerals exist. ❖Geologists study the origins, properties, and compositions of both rocks and minerals. ❖Geologists also explore the Earth for the resources needed in our world. ❖Some search for water in reservoirs beneath Earth’s surface. 4 It is generally divided into two broad areas: Physical geology is the study of Earth materials, such as minerals and rocks, as well as the processes operating within Earth and on its surface. Historical geology examines the origin and evolution of Earth, its continents, oceans, atmosphere, and life. Geology as a discipline is very broad. It can be subdivided into numerous fields or specialties. Geology as a science is interrelated to other science e.g. Engineering, Biology, Chemistry, Physics, …etc. 5 Geology + Engineering = Engineering Geology Geology + Chemistry = Geochemistry Geology + Physics = Geophysics Geology + Biology = Paleontology 6  Origin of the Earth The Early Solar System (Nebular hypothesis) The hypothesis states that about 4.6 billion years ago the matter that became our Solar System was an immense, diffuse, frozen cloud of dust and gas rotating slowly in space (Solar Nebula). This cloud formed from matter ejected from an exploding star. More than 99% of the cloud consisted of hydrogen and helium, the most abundant elements in the Universe. 7  Origin of the Earth The Early Solar System (Nebular hypothesis) Small gravitational attractions among the dust and gas particles caused the cloud to condense into a sphere. As condensation continued, the cloud rotated more rapidly, and the sphere spread into a disk with the matter concentrated at the center that will become the protosun. 8  Over time, the aggregates stuck together. As they increased in size and developed stronger gravitational forces, they attracted more particles. This growth continued until a number of small rocky spheres, called planetesimals, formed, with diameters from a few kms to about 100 km. 9  The planetesimals merged to form a few large planets, including Earth. At the same time that planets were forming, gravitational attraction pulled the gases in the protosun inward, creating extremely high pressure and temperature. 10 Summary Nebula diffuses, roughly spherical, slowly rotating nebula begins to contract As a contraction and rotation, a flat, rapidly rotating disk forms with the matter concentrated at the center that will become the proto- sun 11 12 The Modern Solar System ❑The core became so hot that hydrogen nuclei combined to form the nucleus of the next heavier element, helium, in a process called nuclear fusion. Nuclear fusion releases large amounts of energy. ❑The beginning of nuclear fusion marked the birth of the modern Sun, which still generates its energy by hydrogen fusion. 13 The Modern Solar System ❑The four planets closest to the Sun Mercury, Venus, Earth, and Mars are now mainly rocky with metallic centers are called the terrestrial planets because they are “Earthlike.” In contrast, ❑The four outer planets Jupiter, Saturn, Uranus, and Neptune are called the Jovian planets and are composed primarily of liquids and gases with small rocky and metallic cores. 14 15 Supernova ejects matter rich in pressure waves into space Local concentrations of dust coalesce Balance between gravity and solar wind 16 The Evolution of the Modern Earth Scientists generally agree that the Earth is layered. The center is a dense, hot core composed mainly of iron and nickel. A thick mantle, composed mainly of solid rock, surrounds the core and contains 80% of the Earth’s volume. The crust is a thin surface layer, also composed of rocks. Earth temperature and pressure increase gradually with depth. The mantle rock is so hot that 1:2% of it is melted, so that the entire mantle flows very slowly. 17  This movement allows continents to move across the globe, ocean basins to open and close, mountain ranges to rise, volcanoes to erupt, and earthquakes to shake the planet. Rock is even hotter deeper in the mantle, but the intense pressure prevents it from melting. The outer core is composed of molten metal, the inner core, which is as hot as the surface of the Sun, is under such intense pressure that it is solid. 18 Earth’s Internal Structure Earth’s internal layers defined by: Chemical composition Physical properties Deduced from Seismographs of Earthquakes Meteorites lend support Layers defined by composition: Crust Mantle Iron-Nickel Meteorite Core 19 20 The Differentiated Earth The earth differentiated into layers by density: Least Dense High Si Low Fe 1) Crust 2) Mantle 3) Outer Core 4) Inner Core Most Dense Low Si High Fe Because different minerals have different composition and densities, physical partitioning of the earth led to: chemical differentiation 21  The Crust Si, Al Continental Crust 35 - 40 km Less Dense Oceanic Crust 7 - 10 km More Dense 22 23 The Mantle The asthenosphere may contain a few percent of molten rocks, but the mantle is large solid. Despite this, it will flow. 24 The mantle Si, Mg Solid rock, comprised entirely of ultramafic peridotite (82% of Earth’s volume) Density increases from ~3.5 g/cm3 at top to ~5.5 g/cm3 at base Below ~100 km depth, mantle is hot enough to flow very slowly (~15 cm/year) This is known as convection: hot material rises, cool material sinks 2885 km thick in total, but split into two separate sublayers: Upper mantle (0‒660 km depth) Lower mantle (660‒2900 km depth) Also includes the transition zone between 400‒660 km depth 25 The core A metal alloy containing mainly iron (Fe) and Nickel (Ni), also rich in heavy metals such as platinum (Pt) and gold (Au). Inner core is solid Density is 13 g/cm3 1220 km thick. Outer core is liquid Density is 10‒12 g/cm3 2255 km thick. Flow in the outer core generates the Earth’s magnetic field 26  The Core & The Earth’s Magnetic Field The core is almost completely Fe/Ni alloy. The outer core is liquid, while the inner core is solid. Convection of the outer, liquid core gives rise to the Earth’s magnetic field 27 Summary of Earth’s layers Earth has a layered interior subdivided into: Crust Continental Oceanic Mantle Upper Transitional Lower Core Outer—liquid Inner—solid 28  Why We Study Geology?  Predicting the behavior of Earth systems and the universe.  Conserving soils and maintaining agricultural productivity.  Maintaining quality of water supplies.  Reducing human suffering and property loss from natural hazards. 29 Why We Study Geology? 1. Earth Resources ▪ Energy resources: Oil, Natural Gas 30 Why We Study Geology? 1. Earth Resources ▪ Energy resources: Coal, U 31 Why We Study Geology? 1. Earth Resources ▪ Energy resources: Geothermal Energy 32 Why We Study Geology? 1. Earth Resources ▪ Metals: Fe, Cu, Al, Pd, Zn, Au, Ag,.. 33 Why We Study Geology? 1. Earth Resources ▪ Non-metallic: Sand, Gravel, Limestone, Gems, … 34 35 36 37 Why We Study Geology? 1. Earth Resources ▪ Groundwater 38 Why We Study Geology? 2. Natural Hazards Tsunami 39 Why We Study Geology? 2. Natural Hazards Volcanoes 40  Why We Study Geology? 2. Natural Hazards 2. Natural Hazards Sandstorms Hurricanes 41 Floods 42  Dryness Desertification 43 Why We Study Geology? Earthquakes 44 45 Why We Study Geology? Landslides Subsidence 46 47 48 Why We Study Geology? Military 49 50