Earth Science Endogenic Processes PDF

Earth Science Endogenic Processes Lesson Objectives: 1. identify the sources of the internal heat of the Earth 2. explain the behavior of the rocks under the different types of stress 3. discuss the process of seafloor spreading Earth’s Internal Heat Source  1. Primordial heat of the p...

Earth Science Endogenic Processes Lesson Objectives: 1. identify the sources of the internal heat of the Earth 2. explain the behavior of the rocks under the different types of stress 3. discuss the process of seafloor spreading Earth’s Internal Heat Source  1. Primordial heat of the planet remains from its early stage. the internal heat energy accumulated by dissipation in a planet during its first few million years of evolution  2. Heat from the decay of radioactive elements. radioactive decay by which the spontaneous breakdown of an atomic nucleus causes the release of energy and matter from the nucleus  3. Gravitational pressure a phenomenon in which gravity, acting on the mass of an object, compresses it, reducing its size and increasing the object's density.  4. Dense core material in the center of the planet. The inner core’s intense pressure prevents the iron and other minimal amount of some elements from melting. The pressure and density are simply too great for the iron atoms to move into a liquid state. Rock Behaviors Under Stress  STRESS the force per unit area that is placed on a rock Three Types of Stress 1. Tensional Stress causes rocks to be pulled apart that result to lengthening and break apart. This type of stress can be found at divergent plate boundaries 2. Compressional Stress Causes rocks to fold or fracture. It squeezes rocks together. Compression are the most common type of stress in convergent plate boundaries. 3. Shear Stress happens when forces slide pass each other in opposite direction which results to slippage and translation. This is the most common stress found in transform plate boundaries. Geologic Structures 1. Folds are formed when rocks experienced compressive stress and deformed plastically. It causes bending of rocks. Three Types of Folds A. monocline- is a simple bend in the rock layers where the oldest rocks are at the bottom and the youngest are at the top. B. anticline is a fold that arches upward where the oldest rocks are found at the center of an anticline. C. syncline is a fold that bends downward which rocks are curved down to a center. 2. Faults A rock under ample stress can crack, or fracture. fracture is called a joint because there is a block of rock left standing on either side of a fracture line. The footwall is the rock that place on top the fault, while the hanging wall is below the fault Classification of Faults Normal faults are the most common faults at divergent boundaries In relation to the footwall, it develops as the hanging wall drops down. East African Rift is one of the examples of this type of fault. Reverse faults This type of faults is most common at the convergent boundaries. It forms when the hanging wall moves up. It creates the world’s highest mountain ranges such as Himalayas Mountains and Rocky Mountains Strike slip faults This type of faults formed when the walls move sideways. It is mostly common on transform plate boundaries. The most popular example of this type is San Andreas Fault. Structure and Evolution of Ocean Basins  Seafloor Spreading occurs at mid- ocean ridges, leading to the creation of new ocean floor through volcanic activity  Harry Hess published ‘The History of Ocean Basins' in 1962 Suggesting that the convection of the Earth's mantle was the driving force behind this process.  Sonar a device that bounces sound waves off underwater objects and then record the echoes of these sound waves Evidences that support the idea of seafloor spreading: 1. Evidence from molten materials rocks shaped like pillows (rock pillows) show that molten materials have erupted again and again from cracks along the mid- ocean ridge and cooled quickly. 2. Evidence from magnetic strip rocks that make up the ocean floor lie in a pattern of magnetized stripes which hold a record of the reversals in magnetic field; 3. Evidence from drilling sample core samples from the ocean floor show that older rocks are found farther from the ridge; youngest rocks are in the mid-ocean ridge Structure and Evolution of Ocean Basin 1. Continental shelf Partly shallow extension of the continent underwater 2. Continental slope Transition zone of continental shelf and deep ocean floor. It starts from oceanic crust to continental crust 3. Continental rise It where the ocean actually begins. It is the place where the sediments from land are washed. 4. Abyssal plain The flattest part of the ocean. 50 % of the earth’s surface is being covered by this plain.  5. Island It’s not just a piece of land floating up in the middle of the sea, it is part of the ocean basin that extends up from the ocean floor. 6. Seamount It is an undersea mountain. The erosion caused by waves destroyed the top of a seamount which caused it to be flattened. 7. Trench It is the deepest part of the ocean 8. Mid-oceanic ridge It is where upwelling of magma happens which causes the sea floor to spread Evolution of the Ocean Basin  Wilson Cycle explains the process of the opening (beginning) and the closing (end) of an ocean which is driven by Plate Tectonics Named after the Canadian geophysicist J. Tuzo Wilson  1. Embryonic Ocean Basin 6. Suturing 2. Juvenile Ocean Basin 5. Terminal Ocean Basin 3. Mature Ocean Basin 4. Declining Ocean Basin Details of Wilson Cycle stages Stage Motion Sample Embryonic Uplift East African Rift Valleys Juvenile Divergence Red Sea Mature Divergence Atlantic and Arctic Oceans Declining Convergent Pacific Ocean Terminal Convergent Mediterranean Seas Suturing Convergence Himalayas Mountains