Endogenic Processes PDF

# Endogenic Processes - Defined as a geological process that happens below the surface of the earth. - Endogenic (internal origin) processes are driven by the internal heat of the Earth, which in turn results from the radioactive decay of elements deep beneath the surface. - This heat bubbles upwa...

# Endogenic Processes - Defined as a geological process that happens below the surface of the earth. - Endogenic (internal origin) processes are driven by the internal heat of the Earth, which in turn results from the radioactive decay of elements deep beneath the surface. - This heat bubbles upwards providing a huge driving force that bends, cracks, lifts, and moves Earth's rigid outer layer. ## Types of Endogenic Processes ### Magmatism - Magma is extremely hot liquid and semi-liquid rock located under the Earth's surface. - Magmatism plays a key role in mountain formation, as new ascending magmas produce additional mass and volume to the Earth's surface and subsurface. - Magmatism happens when magma is generated and develops into igneous (magmatic rock). ### Volcanism (Plutonism) - A volcano is the vent through which magma and gases are discharged. - Magma that reaches the surface is called "lava." - Volcanoes are named for Vulcan - the Roman god of fire! - Volcanism is the eruption of molten rock (magma) onto the surface of a planet. ### Metamorphism - Metamorphism, mineralogical, and structural adjustments of solid rocks to physical and chemical conditions differing from those under which the rocks originally formed. - Changes produced by surface conditions such as compaction are usually excluded. - The most important agents of metamorphism include temperature, pressure, and fluids. ## Other Tectonic Forces and Processes ### Deformation - It refers to any change in the shape or size of a rock as a response to the stress. #### Classification of Deformation of Rocks - **Stress** - The force applied to a rock and may cause deformation. - **Faulting** - A crack in the earth's crust resulting from the displacement of one side with respect to the other. #### Types of Stress - **Compression** - A type of stress that decreases the volume of a material. - **Tension** - A type of stress that pulls a material apart. - **Shear** - A type of stress that causes a material to twist. #### Faulting - **Normal Fault** - A dip-slip fault in which the block above the fault has moved downward relative to the block below. - **Reverse Fault** - A dip-slip fault in which the upper block, above the fault plane, moves up and over the lower block. - **Strike-Slip Fault** - A fault on which the two blocks slide past one another. ### Plate Motion - Plate motions cause mountains to rise where plates push together, or converge, and continents to fracture and oceans to form where plates pull apart or diverge. - The continents are embedded in the plates and drift passively with them, which over millions of years results in significant changes in Earth's geography. #### Plate Motion: Early Theories and Hypothesis - **Continent Accretion Theory** - Which proposed that the continents have always been stationary with gradual addition of new material. - **Continent Assimilation Hypothesis** - Explained how the ocean areas accumulated the denser elements then subsided to form basins. - **Expanding Earth Hypothesis** - The present continents split apart with the expansion of Earth and that the continents combined could half of the current Earth's surface area. #### Plate Motion: Modern Theory - **Continental Drift Theory** - The gradual movement of the continents over time. The upper layer of the crust is broken down into large slabs called plates, which sit on a fluid level of molten rock. The movement if this lower molten layer, called plate tectonics, causes the plates to shift. - **Alfred Wegener (1912)** - A German geophysicist and meteorologist. Wegener theorized that the continents once existed as a single landmass, which he called Pangaea (275 to 175 million years ago). - **Pangaea** - Comes from the Greek word "Pan" meaning “all” and "Gaea" meaning "Earth" or "All of Earth" or "All lands". It is surrounded by water called "Panthalassa" which means "All water" in Greek. - **Laurasia and Gondwanaland** - Pangaea started to break up into two smaller supercontinents, called Laurasia and Gondwanaland, during the Jurassic period. By the end of the Cretaceous period, the continents were separating into land masses that look like our modern-day continents. #### 4 Evidences of Continental Drift - **Continental Jigsaw Puzzle** - Wegener suspected that the continents might have been joined when he noticed remarkable similarity between them. The fitting of both South America's and Africa's coastlines with each other, is a perfect example of the continental jigsaw puzzle. - **Fossil Correlation** - Fossil plants in India, South Africa, Australia, Antarctica and South America are similar to each other and the same goes with the fossil animals. Similar fossil animals and fossil plant existing in different continents at the same time. - **Rock and Mountain Correlation** - Since the continents fit to each other, Wegener discovered that there are continuous rock types and mountains from one continent to another. Continuous rock types and mountain belts are evident in Appalachian Mountains in north eastwards of North America and Caledonian Mountains in British Isles and Scandinavia. - **Paleoclimatic Data** - Wegener observed the paleoclimatic (ancient climate) data in supporting the continental drift. Glacial deposits indicate that near the end of Paleozoic era (between 200-300 million years ago), ice sheets covered extensive areas of Southern Hemisphere. ### Rejecting the Continental Drift - He could not explain the mechanism of continental drift. - He explained fossil similarities based on land bridges in the past, which allowed plants and animals to migrate across one continent to another. - He was a meteorologist that time (proposing the continental drift) which made the scientific community considered him as an outsider who proposes a major concept in geology. - He thought that the continents were moving at a very rapid state. - Scientists ascertained that Wegener's calculations were inaccurate. ### Plates of the World - **7 major plates in the world** - Pacific Plate, African Plate, North American Plate, Indo-Australian Plate, South American Plate, Eurasian Plate, Antarctic Plate. - **Largest minor plates in the world** - Juan de Fuca Plate, Arabian Plate, Caribbean Plate, Cocos Plate, Nazca Plate Philippine Plate, Scotia Plate. ### Plate Tectonics - Plate tectonics is a scientific theory that explains how major landforms are created as a result of Earth's subterranean movements. - The theory, which solidified in the 1960s, transformed the earth sciences by explaining many phenomena, including mountain building events, volcanoes, and earthquakes. ### Plate Boundaries - Plate boundaries are found at the edge of the lithospheric plates and are of three types, convergent, divergent and conservative. - A plate boundary is a three-dimensional surface or zone across which there is a significant change in the velocity (speed or direction) of motion of one lithospheric plate relative to the adjacent lithospheric plate. #### Types of Plate Boundaries - **Divergent Boundary** - Also called as constructive margins where two plates move apart, resulting in upwelling of material from the mantle to create new seafloor. - **Convergent Boundary** - Also called as destructive margins where two plates move together, resulting in oceanic lithosphere being thrust beneath an overriding plate eventually to be reabsorbed into mantle. Convergence can also result in the collision of two continental plates to create a mountain system. - **Subduction Zone** - A collision between two of Earth's tectonic plates, where one plate sinks into the mantle underneath the other plate. Subduction zones are locations on Earth where the oceanic material of one tectonic plate dives below the material (oceanic or continental) of another tectonic plate into the mantle. #### Types of Convergent Boundary - **Oceanic-Continental** - Whenever the leading edge of a continental plate converges with an oceanic plate, the buoyant continental plate remains floating, whereas the denser oceanic slab sinks into the asthenosphere - **Oceanic-Oceanic** - A collision between two plates composed of oceanic lithosphere. Even though this boundary involves the same type of lithosphere, one of the plates will still subduct beneath the other. This activity will create a chain of volcanic island called a volcanic island arc. - **Continental-Continental**- Occur when two continental plates move towards each other. Both plates are less dense, sO neither subducts under the other. Instead, the plates collide and push upwards forming large mountain ranges. ### Seafloor Spreading - A geologic process in which tectonic plates split apart from each other because of mantle convection--- the slow, churning motion of Earth's mantle. - It occurs at divergent plate boundaries.