Earth Sci Reviewer PDF

# EARTH SCI REVIEWER ## Exogenic Processes ### Sedimentation Sedimentation is the process by which particles like sand or silt settle from a fluid, such as water, to form layers. It occurs naturally and is used in water treatment to separate solids. ### Factors Causing Sedimentation - GRAVITY -...

# EARTH SCI REVIEWER ## Exogenic Processes ### Sedimentation Sedimentation is the process by which particles like sand or silt settle from a fluid, such as water, to form layers. It occurs naturally and is used in water treatment to separate solids. ### Factors Causing Sedimentation - GRAVITY - TEMPERATURE - PARTICLE SIZE & DENSITY - CHEMICAL REACTIONS ### Factors transporting sediments - **Waterflow:** Fast water keeps particles suspended; slow water enables settling. - **Wind:** Carries lighter particles like sand over land, seen in deserts and coastal areas. - **Ice (glaciers):** Transports sediment frozen inside, released upon melting - **Human activity:** Deforestation, construction, and agriculture accelerate sediment movement ## MASS WASTING Mass wasting (also called mass movement) is the gravity driven processes where soil, rock, and debris move downhill, shaping landforms over time. This movement can be shallow or rapid, influenced by factors like material type, water content, and slope steepness. ### Classification - **Landslide:** Landslides are one type of mass wasting. This happens when a large amount of rock and soil suddenly separates and slides quickly down a slope. This can often be brought on by events like intense rain, earthquakes, or human activity that weakens the land. - **Rock Falls:** The sudden falling movement of rock or debris down a steep slope. Rockfalls are usually the result of the breaking or loosening of rocks through weathering or seismic activity. Such events typically involve free falling rock fragments from cliffs or on steep mountain slopes. - **Soil Creeps:** Creeps are very slow, gradual downhill movement of soil and loose rock. Factors such as freeze-thaw cycles, moisture changes, and soil expansion from temperature shifts gradually push soil particles downslope, causing objects like trees and buildings to tilt over time. ### Factors causing mass wasting 1. **Composition:** One of the main factors that causes mass wasting is the composition of the slope material. If the slope is made up of clay, mass wasting would likely happen, as they are shaped in a way that they can absorb water, causing it to prevent the water from filtering the ground. 2. **Weathering:** Weathering also is one of the factors that causes Mass Wasting. Physical and chemical weathering weakens rocks and soils, making them more prone to Mass Wasting. 3. **Earthquake shocks:** Earthquake shocks result in portions of mountains and hills to break loose and slide downwards. The vigorous shaking of an already-unstable slope by seismic waves may cause it to fail. Typically, the higher the magnitude of an earthquake, the more mass wasting will occur. ## ENDOGENIC PROCESS Endogenic Processes are geological processes that occur beneath the surface of the earth. ### FOLDING Folding is an endogenic process that indicates the bending and alteration of the Earth's crust as a result of internal forces, usually induced by tectonic plate movements (COMPRESSIONAL FORCE). Folding is an important geological process that influences landscapes and alters Earth's topography throughout time. #### Different types of folding - **Monocline:** A simple "one step" bend in the rock layers. Mono- refers to its layers that are only folded in one direction. - **Anticline:** A fold that arches upward. Rocks dip away from the center of the fold. - **Syncline:** A syncline is a fold that bends downward. Formed by compressive stress in the Earth's crust. - **Recumbent folds:** Nearly horizontal folds formed by extreme compression. - **Ptygmatic folds:** Small, tightly folded layers of rock that look like "kinks" or "zig-zags". - **Parasitic folds:** Small folds that form on top of larger folds. They're like smaller "baby" folds that follow the pattern of the bigger fold. - **Plunging folds:** A fold where the central axis (the highest or lowest point) of the fold is tilted. - **Overturned folds:** The axial plane is inclined and both limbs dip in the same direction but at different angles. - **DOMES:** A structure formed when upward-folded rocks make a circular or dome shape. - **Basins:** The opposite of a dome, rocks bend downwards in a circular shape creating a bowl-like depression. ### Factors Affecting Folding - **Temperature:** Higher temperatures increase rock ductility, making them more prone to folding. - **Pressure:** Increased pressure at greater depths enhance the potential for folding as rocks become more pliable. - **Rock type:** Rocks' composition, structure, and hardness influence their ability to fold. Soft, ductile rocks fold more easily than hard, brittle rocks. - **Rate of Deformation:** Slow, prolonged compression tends to result in more pronounced folding compared to rapid, short-lived stress. - **Time:** Longer durations of compressive stress allow more time for rocks to fold and deform. - **Depth:** Deeper rocks, subjected to greater pressure and temperature, are more likely to undergo folding. ## FAULTS Faulting is a process characterized by break and slip of rocks in the earth's crust along a fault plane. Faults arise because of tectonic forces responsible for stress in the earth's crust, which eventually cause deformation (Tensional forces). ### Types of Faults - **Normal fault:** In a normal fault, the hanging wall moves downward relative to the footwall. In simple terms, one side of the fault moves downward with respect to the other side. Normal faults are common at divergent plate boundaries where the Earth's crust is stretching. - **Reverse fault:** This is the opposite of a normal fault. In a reverse fault, the hanging wall moves upward relative to the footwall. In simple terms, one side moves up. Reverse faults typically occur at convergent plate boundaries where tectonic plates are colliding and undergoing compression. - **Strike slip-fault:** In a strike-slip fault, the movement is primarily horizontal, with minimal vertical displacement. The rocks on either side of the fault slide past each other horizontally. The San Andreas Fault in California is a famous example of a strike-slip fault. - **Transform fault:** Transform faults are a type of strike-slip fault that forms the boundary between two tectonic plates. They accommodate horizontal motion between the plates. The motion is typically parallel to the fault's strike. ### Causes of Faults - **TENSION:** Pulls rocks apart, leading to normal faults. - **COMPRESSION:** Pushes rocks together, resulting in reverse faults. - **SHEARING:** Causes horizontal movement, creating strike-slip faults. ### 3 Types of Plate Boundaries - **CONVERGENT BOUNDARIES:** Reverse faults due to compression. - **DIVERGENT BOUNDARIES:** Normal faults due to tension. - **TRANSFORM-FAULT BOUNDARIES:** Strike-slip faults due to lateral movement. - **STRESS ACCUMULATION:** Over time, stress builds up in the crust until it exceeds the strength of rocks, causing them to fracture and slip along faults. ## What is Volcanism? - A geological process involving the eruption of molten rock (magma) from the Earth's interior to its surface. - This molten rock, once it reaches the surface, is called lava. - Volcanic eruptions can range from gentle, effusive flows of lava to explosive events that eject ash, gas, and pyroclastic material high into the atmosphere. ### Types/Classifications of Volcanism #### Based on Tectonic Setting - **Divergent Boundary Volcanism:** - happens where tectonic plates are moving apart. - as the plates diverge, magma from the mantle rises to fill the gap, leading to the creation of a new crust. - the magma is typically basaltic, which has low viscosity and forms gentle lava flows. - **Convergent Boundary Volcanism:** - occurs at subduction zones where an oceanic plate sinks beneath another plate (either oceanic or continental). - the subducting plate melts as it descends into the mantle, generating magma that rises to the surface. - The magma is often andesitic or rhyolitic, leading to explosive eruptions. - **Hotspot Volcanism:** - caused by mantle plumes, which are upwellings of hot mantle material that melt the crust above them. - hotspots are independent of tectonic plate boundaries and can occur in the middle of tectonic plates. - **Intraplate Volcanism:** - occurs within a tectonic plate rather than at plate boundaries. - this type is often related to mantle plumes or rift zones forming within continental plates. #### Based on Composition of Erupted Material - **Silicate Volcanism:** - the most common type of volcanism on Earth, involving magma rich in silicate minerals depending on the silica content, eruptions can range from gentle lava flows (low-silica basalt) to highly explosive eruptions (high-silica rhyolite). - **Mud Volcanism:** - unlike typical silicate volcanism, mud volcanism involves the eruption of mud, water, and gasses, often in sedimentary basins. - this type of volcanism is driven by the release of pressurized gasses, particularly methane. - **Cryovolcanism:** - also known as ice volcanism, this type occurs on icy bodies in the outer Solar System instead of molten rock, cryovolcanoes erupt volatile substances like water, methane, or ammonia in a liquid or gas state. - the extremely low temperatures allow these substances to act like magma. - **Sulfur Volcanism:** - this type of volcanism involves eruptions dominated by sulfur and sulfur compounds instead of silicate materials. - It is more common on some extraterrestrial bodies than on Earth. ### What are the Causes of Volcanism? - **Increase in Pressure within Magma Chambers:** As magma accumulates in the chamber, pressure builds up over time. This increase in pressure can eventually force magma upward, leading to volcanic eruptions. #### Tectonic Plate Boundaries - **Divergent Boundaries (Plates Moving Apart):** The separation of two tectonic plates creates gaps, allowing magma from the mantle to rise and fill these spaces. - **Convergent Boundaries (Subduction Zones):** One tectonic plate subducts (moves beneath) another. This movement introduces seawater and sediments into the mantle, melting rock and forming new magma. #### Non-Tectonic Factors - **Crystallization of Magma:** As the temperature decreases, older magma begins to crystallize and sink. This displacement pushes fresh magma upward, potentially triggering an eruption. - **Decrease in External Pressure:** Factors such as typhoons, glacial melting, and erosion can reduce the pressure acting on the surface above the magma chamber. Lower external pressure can decrease the chamber's ability to contain magma, increasing the likelihood of an eruption. ## EFFECTS OF VOLCANISM - **Environmental Effects:** Ash fall can cover houses, buildings, roads, and fields, potentially causing damage and disrupting daily life. Lava flows can destroy structures and landscapes. Pyroclastic flows are deadly hot gas and ash mixtures that travel very quickly down volcano slopes, killing everything in their path. Gases released during eruptions can be hazardous to human health, especially for those with respiratory problems. - **Climate Change:** Sulfur dioxide emissions can combine with water vapor in the stratosphere to form sulfate aerosols that reflect sunlight back into space, cooling the Earth's surface. - **Geological effects:** Eruptions create new landforms like lava domes and cinder cones. Volcanic ash and debris can accumulate over time to form thick deposits. Lahars (volcanic mudflows) can occur when volcanic debris mixes with water. - **Human impact:** Some eruptions can be catastrophic for nearby towns and cities, depending on eruption style and location. Evacuations may be necessary, posing challenges for large populations. On the positive side, some volcanoes produce rich soils suitable for farming. ## EARTHQUAKE - Is when the Earth's surface shakes because of a sudden release of energy in the crust, creating seismic waves. - It can be mild and barely felt or strong enough to cause major damage. - Most earthquakes happen due to faults in the Earth but can also be triggered by volcanic eruptions, landslides, or human activities like mining. ### Types/Classification of Earthquake - **Tectonic Earthquakes:** Result from shifts in the Earth's plates, releasing vast amounts of energy that can lead to severe destruction. - **Volcanic Earthquakes:** Happens when magma moves beneath the Earth's surface. Though generally smaller than tectonic earthquakes, they can still cause considerable damage. - **Collapse Earthquakes:** Occur when structures such as buildings fall. These are usually minor in magnitude, yet they can be fatal in densely populated areas. - **Explosion Earthquakes:** Are triggered by explosive detonations. Typically small in scale, they can be destructive if they happen close to populated locations. ## Earthquakes create seismic waves, which are vibrations that travel through the Earth's interior or along its surface. - **P-waves (Primary or Compressional Waves):** These are the fastest seismic waves and can travel through solids, liquids, and gasses. - **S-waves (Secondary or Shear Waves):** S-waves are slower than P-waves and can only travel through solids. - **Surface Waves:** These waves travel along the Earth's surface and are typically more destructive during earthquakes. Love waves and Rayleigh waves are the two main types of surface waves, causing horizontal and elliptical particle motion, respectively. ### What are the causes of an earthquake? - **Tectonic Movements:** Tectonic Plates: The Earth's crust is divided into large plates that float on the semi-fluid asthenosphere. #### Types of Plate Boundaries: 1. **Convergent Boundaries:** Plates collide, often causing strong earthquakes due to subduction (one plate forced under another). 2. **Divergent Boundaries:** Plates move apart, creating tension and fractures that lead to earthquakes. 3. **Transform Boundaries:** Plates slide past each other, building friction until it releases as an earthquake. #### Volcanic Activity: Rising magma exerts pressure on the surrounding rocks, leading to fracturing and seismic activity. > **Human-Induced Causes:** 1. Mining 2. Reservoir-Induced Seismicity 3. Fracking #### Primary Effects 1. Ground Shaking 2. Ground Rupture #### Secondary Effects 1. Tsunamis 2. Landslides 3. Liquefaction 4. Fires #### Tertiary Effects 1. Economic Loss 2. Social Disruption 3. Environmental Impact