EarthSci Quarter 2 PDF

**EXOGENIC PROCESS** **Weathering** is the process of breakdown of rocks at the Earth's surface, by the action of water, ice, acids, salts, plants, animals, gravity and changing temperatures. **Agents Of Weathering** 1. 2. 3. 4. 5. **TYPES OF WEATHERING** **Physical Weathering** -is cau...

**EXOGENIC PROCESS** **Weathering** is the process of breakdown of rocks at the Earth's surface, by the action of water, ice, acids, salts, plants, animals, gravity and changing temperatures. **Agents Of Weathering** 1. 2. 3. 4. 5. **TYPES OF WEATHERING** **Physical Weathering** -is caused by the effects of changing temperatures on rocks, causing the rock to break apart. - - - **Chemical Weathering** -is caused by rainwater reacting with the mineral grains in rocks to form new minerals (clays) and soluble salts. - - - - - **Biological Weathering** -occurs when rocks are weakened by different biological agents like plants and animals. - - **ENDOGENIC PROCESSES** **PLUTONISM AND VOLCANISM** **TWO SOURCES OF HEAT** **Residual Heat** - thermal energy left over from the formation of Earth via bombardment and accretion **Radioactive Decay** - the release of energy and energetic particles from radioactive materials heat up surrounding **Magma** -forms from partial melting of mantle rocks. **Partial melting** -The minerals that compose them melt at different temperatures. -Takes place because rocks are not pure materials. The two main mechanisms through which rocks melt are **decompression** **melting** and **flux melting**. **Decompression melting** -takes place within Earth when a body of rock is held at approximately the same temperature but the pressure is reduced. **Flux melting** -Happens if a rock is close to its melting point and some water or carbon dioxide is added to the rock. Magma escaped in two forms: intrusion and extrusion. **Intrusion** -Is magma that moves up into a volcano without erupting. -cause the volcano grows on the inside. **Plutonism** \- refers to all sorts of igneous geological activities taking place below the Earth\'s surface. **Plutonite** -When the process of crystallization takes place inside the crust. **Extrusion** -an eruption of magmatic materials that causes land formation on the surface of the Earth. **Volcanism** -Is used to describe all geological phenomena that occur on the natural terrestrial surface. **Volcanite** -Molten material in the form of lava that undergoes the process of crystallization on the natural terrestrial surface gives birth to rock formations. **Plutonite** - crystalized inside the earth **Volcanite** - crystalized outside or on the surface **ENDOGENIC PROCESSES** **METHAMORPHISM OF ROCKS** **METAMORPHISM** \- is the process of change in the form and structure of rocks due to intense heat and pressure. It comes from the Greek word \- "meta" means change \- "morphe" means form. **METAMORPHIC AGENTS** - \- the most important factor because it provides the energy to drive the chemical changes which result in the recrystallization of minerals. The heat increases as the depth increases. - \- The pressure just like heat also increases with depth, and the buried rocks are subjected to the force or stress. Heat and pressure cause physical changes to buried rocks. - \- Chemically active fluids enhance the metamorphic process. **TYPES OF METAMORPHISM** - \- Most common form of metamorphism that occurs in broad areas. - \- Takes place when the very hot magma moves up through the crystal rocks and brings with it high levels of heat. - \- Is the process where rocks along the subduction zone are altered due to high pressure. \- Occurs at the subduction area - \- occurs at lower temperature and pressure which transform sedimentary rocks that had undergone diagenesis into low grade metamorphic rocks through relatively low temperature and pressure. \- Occurs below sedimentary rock layer - \- Alteration by hot, chemically aggressive water. \- Dominant process near mid ocean ridge magma. \- Occurs in mid ocean ridges. - \- It occurs when high-speed projectiles called meteorites (fragments of asteroids) strike the surface of the earth. **TYPES OF METAMORPHIC ROCK** - \- These have a planar foliation caused by the preferred orientation (alignment) of minerals and are formed under differential stress. \- They have a significant amount of sheet silicate (platy minerals) and are classified by composition, grain size, and foliation type. - \- These have no evident planar fabric or foliation, crystallized under conditions where there was no differential stress, and are composed of equant minerals only. \- These are classified mainly by the minerals present or the chemical composition of the protolith. **TYPES OF STRESSES IN THE EARTH CRUST** - **→←** - **←→** - **↑↓** **THE FORMATION OF FAULTS AND FOLDS** **Tectonic Plates** \- The Earth's crust is divided into plates, known as tectonic plates, and these plates move due to the convection currents in the Earth's interior. **Plate Movements** \- The movement of the plates depends on the boundaries between them. These boundaries can be convergent, divergent, or transform. **ROCK DEFORMATION** **Compressional Stress** \- causes rocks to be squeezed into each other. **Tensional Stress** \- pulls rocks apart and SHEAR STRESS causes rocks to slide opposite each other. **Fracture** \- When subjected to stress, rocks can deform by either breaking (fracture) or bending (fold). **TWO TYPES OF FAULT** - -involve the vertical movement of the blocks of rock. - \- involves a horizontal movement of blocks of rock and is caused by shear stress. **FOLDS** -Deep within the crust, where pressure and temperature are high, rocks are plastic-like; thus, they do not break but they tend to bend or fold. When rocks become thinner, they are pulled apart. **TYPES OF FOLD** **ANTICLINE** -when blocks of rock are bent upwards, they form anticline structures. **SYNCLINES** -are formed when blocks of rock bend downwards. **MONOCLINES** -a slightly bent rock from the parallel undeformed layers forms monoclines **LAYERS OF EARTH** **Temperature and composition** -Temperatures deep inside the earth can range from 4,000-6,000°C. -The temperatures increase as you go deeper into the earth. - - - - - **Composition** -Each layer has a distinct set of rocks and minerals that make it unique, however they all contain some of the same things, such as iron. Earth's crust is much like a "skin" consisting of two types, **oceanic** and **continental**. **THE LAYERS** **Lithosphere** -The lithosphere consists of the crust and the upper mantle... -Continental crust is about 25-90 km (15-55mi) thick and divided into tectonic plates. -Oceanic crust, which is much thinner than continental crust at only 6-11km (3-6 mi) thick, is where new crust is formed. -Both types "float" on the denser mantle **Asthenosphere** \- is more fluid than the rigid Lithosphere above it, with a plastic-like texture. **Mantle** -the Mohorovicic discontinuity, or Moho. The Moho is characterized by a drastic increase in seismic rate, discovered by **Andrija Mohorovicic** in 1909. The Upper Mantle is fairly plastic. **Core** \- there are two parts, an Outer Core and an Inner Core. \- The Outer Core is liquid iron alloy, at extremely high temperatures flowing molten. \- The Inner Core is thought to be solid iron. **CONTINENTAL DRIFT** **CONTINENTAL DRIFTING IDEA** -**Abraham Ortelius**, a Brabantian cartographer and geographer and known as the creator of the first modern atlas (Theatrum Orbis Terrarum or Theatre of the World) **CONTINENTAL DRIFT THEORY** -It refers to the movement of the Earth's continents relative to each other, appearing to "drift" across the ocean bed. \- This theory is publish in the book, "**Origin of Continents and Oceans**" by **Alfred Wegener** **Alfred Wegener (1880-1830)** -a [German meteorologist.] -According to Wegener, the continents were once joined together in a one large landmass called "supercontinent" or "**Pangaea"** **WEGENER\'S EVIDENCE** A. **Topographic Evidence** - B. **Fossil Correlation** - C. **Rock Formation** - D. **Paleoclimatic Evidence** - **SEA-FLOOR SPREADING** - - - - - - **SEA-FLOOR SPREADING EVIDENCE (1960s)** 1. 2. 3. **STRUCTURE AND EVOLUTION OF OCEAN BASINS** **SONAR** AND **BATHYMETRY** These features on the ocean basin are obtained by using different technologies, such as echosounder,side-scan sonar, and satellites. Usually, **sonar** is used to determine accurately the time between the emission of a strong acoustic pulse, and the detection of its echo. The measurement of ocean depths and the charting of the shape or topography of the ocean floor can be measured which is called a **bathymetry** **STRUCTURE OF OCEAN BASIN** **MID-OCEANIC RIDGE** \- This feature constitutes 23 % of the Earth' surface. \- It is normally found rising above the ocean floor at the center of the ocean basins. **OCEANTRENCHES** \- They are long narrow, steep-sided depressions that contain the greatest depths in the ocean. **ABYSSAL HILL/PLAIN** \- found on the deep ocean floor, meanwhile, abyssal plains are so flat because they are covered with sediments that have been washed off the surface of thecontinents for thousands of years. **SEAMOUNTS** \- These feature can be very large submerged volcanic mountain reaching heights up to 10,000 feet. \- However, they remain submerged under the surface of the water. **GUYOT** \- It is similar to a seamount, but it is submerged volcanic mountain with a flat top. \- Guyot's structure is due to erosive processes caused by waves after years. **CONTINENTAL RISE** \- This feature found gently sloping area before the ocean floor and at the base of the continental slope and formed by emerging accumulate deposits at the mounts of many submarine canyons. **CONTINENTAL SHELF** \- a continental shelf is a shallow, gently sloping part of the continent crust. **CONTINENTAL SLOPE** \- This part of the ocean basin extends and slopes after the continental shelf. \- The boundary between the continental slope and shelf is called continental shelf break.  **OCEAN BASINS ARE DIVIDED INTO** **THREE MAJOR PROVINCES** **1. CONTINENTAL MARGINS** \- the submarine edge of the continental crust distinguished by relatively light and isostatically high-floating material in comparison with the adjacent oceanic crust. \- It is the name for the collective area that encompasses the continental shelf, continental slope, and continental rise. 2\. **DEEP-OCEAN BASINS** \- parts of the oceans where deep water prevails \- cover the greatest portion of the Earth\'s surface 3\. **MID-OCEAN RIDGES** \- occur along divergent plate boundaries, where new ocean floor is created as the Earth\'s tectonic plates spread apart. **THE EVOLUTION OF OCEAN BASINS** The oldest rocks found in the ocean basin are approximately 200 million years ago. The **oceanic crust** is much [younger] than most **continental crust.** The reason for this difference is that tectonic processes destroy old oceanic rocks. When oceanic crust is subducted, the oceanic rock is returned to the Earth's mantle. Many of these subduction zones occur at the continental margins where the oceanic crust meets continental crust. Subduction also creates the oceans' deep trenches. **THE WILSON CYCLE** -It is a model that describes the opening and closing of ocean basins and the subduction and divergence of tectonic plates during the assembly and disassembly of supercontinents.  FIVE OCEAN BASINS FROM LARGEST TO THE SMALLEST Pacific-the largest and deepest ocean on earth. It covers 65,200,000 sqkm a third of the Earth\'s surface Atlantic-has the simplest pattern of ocean-floor ages. Indian Southern Arctic **OCEAN BASIN AND CONTINENT BOUNDARIES** \- Both the continental and oceanic crusts lie over a more uniform layer called mantle. \- However, in terms of location and thickness, ocean basins lie much lower than sea level, more dense, and thin. **Petrology** \- is a branch of geology that deals with the origin, composition, structure, and classification of rocks. **Stratigraphy** \- is the study of rock layers (strata) and layering (stratifications). **Paleontology** \- studies the life that existed to, or sometimes at the start of, the Holocene epoch (the current geologic epoch) **Stratification** \- the layering that occurs in most sedimentary rocks and in those igneous rocks formed at the Earth's surface as from lava flows and volcanic fragmental deposits. **COMMON STRUCTURE AND TEXTURE OF SEDIMENTARY ROCKS** Sedimentary rocks have the general characters of occurring in the form of a [series of beds]. This phenomenon is known as "**Stratification**" or "**Bedding**" When the thickness of individual beds is very small it is called "**lamination**". This is an inherent, primary character of sedimentary rocks is not a continuous process. The short break in sedimentation is represented by the bedding plane. Bedding plane is the plane of contract between any two adjacent beds of strata **METHODS OF DETERMINING THE AGE OF STRATIFIED ROCKS** **RELATIVE DATING** Arrange the layers of stratified rocks in proper order. - - - **ABSOLUTE DATING** Determines the exact numerical age of a historical remainder. - - - - **THE HISTORY OF EARTH THROUGH GEOLOGIC TIME** **GEOLOGIC TIME SCALE** - - - - - - - -