Pointers for review- 1o.docx

**First Quarter Periodical Test** **Pointers to Review** **Distribution of Active Volcanoes** 1. **Locations**: - Most active volcanoes are found along tectonic plate boundaries, especially in the **Ring of Fire** around the Pacific Ocean. - **Mid-ocean ridges** (divergent...

**First Quarter Periodical Test** **Pointers to Review** **Distribution of Active Volcanoes** 1. **Locations**: - Most active volcanoes are found along tectonic plate boundaries, especially in the **Ring of Fire** around the Pacific Ocean. - **Mid-ocean ridges** (divergent boundaries) also have volcanic activity, such as the Mid-Atlantic Ridge. - **Hot spots**, like the Hawaiian Islands, can create volcanoes away from plate boundaries. 2. **Features**: - **Volcanic Arcs**: Chains of volcanoes parallel to plate boundaries, such as the Andes in South America. - **Shield Volcanoes**: Broad, gently sloping volcanoes formed by fluid lava, found at hot spots like Hawaii. - **Strato volcanoes**: Steeper, more explosive volcanoes found at convergent boundaries, such as Mount St. Helens. **Distribution of Earthquake Epicenters** 1. **Locations**: - Earthquake epicenters are commonly found along **tectonic plate boundaries** where plates interact. - **Transform Boundaries**: Earthquakes occur along faults where plates slide past each other, like the San Andreas Fault. - **Convergent Boundaries**: Earthquakes are frequent where plates collide and subduct, such as along the Himalayas and the Pacific Ring of Fire. - **Divergent Boundaries**: Earthquakes occur as plates move apart, creating rift valleys or mid-ocean ridges. 2. **Types**: - **Shallow Earthquakes**: Typically occur at divergent and transform boundaries. - **Intermediate and Deep Earthquakes**: Common at convergent boundaries, especially in subduction zone. **Distribution of Major Mountain Belts** 1. **Locations**: - **Convergent Boundaries**: Major mountain belts form where tectonic plates collide, such as the Himalayas (India-Eurasia collision) and the Rockies (North America-Pacific collision). - **Orogeny**: The process of mountain building, typically occurring at convergent boundaries. 2. **Features**: - **Fold Mountains**: Formed by the folding of the Earth\'s crust, such as the Alps and the Himalayas. - **Fault-Block Mountains**: Created by faulting, like the Sierra Nevada. **Relationships between Volcanoes, Earthquakes, and Mountain Belts** 1. **Tectonic Plate Boundaries**: - **Divergent Boundaries**: Create mid-ocean ridges and rift valleys, associated with volcanic activity and earthquakes. - **Convergent Boundaries**: Lead to mountain building, volcanic arcs, and deep earthquakes due to subduction. - **Transform Boundaries**: Cause earthquakes and faulting but not significant volcanic activity. 2. **Geological Activity**: - **Volcanoes and Earthquakes**: Often found together at plate boundaries due to the movement of magma and tectonic forces. - **Mountain Belts**: Frequently associated with convergent boundaries and can include volcanic activity, especially in subduction zones. ### **Divergent Plate Boundaries** 1. **Definition**: Divergent boundaries occur where two tectonic plates move away from each other. 2. **Characteristics**: - **Mid-Ocean Ridges**: Example includes the Mid-Atlantic Ridge. - **Rift Valleys**: Example includes the East African Rift Valley. - **New Crust Formation**: Magma rises to create new oceanic crust. 3. **Geological Features**: Volcanic activity, shallow earthquakes. ### **Convergent Plate Boundaries** 1. **Definition**: Convergent boundaries occur where two tectonic plates collide or move towards each other. 2. **Types**: - **Ocean-Continent Convergence**: Oceanic plate subducts beneath a continental plate, forming trenches and volcanic mountain ranges. Example: The Andes Mountains. - **Ocean-Ocean Convergence**: One oceanic plate subducts beneath another, forming deep ocean trenches and volcanic island arcs. Example: The Mariana Trench. - **Continent-Continent Convergence**: Two continental plates collide, forming mountain ranges. Example: The Himalayas. 3. **Geological Features**: Mountain ranges, deep ocean trenches, volcanic activity, strong earthquakes. ### **Transform Plate Boundaries** 1. **Definition**: Transform boundaries occur where two tectonic plates slide past each other horizontally. 2. **Characteristics**: - **Fault Lines**: Example includes the San Andreas Fault. - **No Crust Creation or Destruction**: Plates slide past each other without creating or destroying crust. 3. **Geological Features**: Earthquakes, fault lines, no significant volcanic activity. ### **General Review Points** 1. **Plate Movements**: - Divergent: Plates move apart, creating new crust. - Convergent: Plates move towards each other, leading to subduction or mountain building. - Transform: Plates slide past each other, causing earthquakes. 2. **Landform Formation**: - Divergent: Mid-ocean ridges, rift valleys. - Convergent: Mountain ranges, ocean trenches, volcanic arcs. - Transform: Fault lines, earthquake zones. 3. **Impact on Earth's Surface**: - Divergent: Creates new geological features like mid-ocean ridges. - Convergent: Forms significant features such as mountain ranges and deep trenches. - Transform: Causes seismic activity along fault lines. ### Divergent Plate Boundaries 1. **Process**: - Plates move away from each other. - As they separate, magma rises from the mantle to create new crust. 2. **Geological Features**: - **Mid-Ocean Ridges**: Underwater mountain ranges formed by volcanic activity, such as the Mid-Atlantic Ridge. - **Rift Valleys**: Depressions formed on land where continental plates pull apart, such as the East African Rift. - **New Oceanic Crust**: Created at mid-ocean ridges as magma solidifies. 3. **Earthquakes**: - Generally shallow and occur due to the stretching and breaking of the crust. **Convergent Plate Boundaries** 1. **Process**: - Plates move towards each other. - One plate is often forced below the other (subduction), or they collide and push upwards. 2. **Types**: - **Oceanic-Continental Convergence**: - Oceanic plate subducts beneath the continental plate. - Forms **deep ocean trenches** (e.g., Mariana Trench) and **volcanic arcs** (e.g., Andes Mountains). - **Oceanic-Oceanic Convergence**: - One oceanic plate subducts beneath another. - Creates **volcanic island arcs** (e.g., the Aleutian Islands) and **deep ocean trenches**. - **Continental-Continental Convergence**: - Plates collide and crumple, forming **mountain ranges** (e.g., Himalayas). 3. **Earthquakes**: - Can be shallow to deep, depending on the type of convergence and the depth of the subduction zone. **Transform Plate Boundaries** 1. **Process**: - Plates slide past each other horizontally. - No new crust is created or destroyed; instead, stress builds up until it\'s released as an earthquake. 2. **Geological Features**: - **Fault Lines**: Fractures in the Earth\'s crust where movement has occurred, such as the San Andreas Fault. - **Earthquakes**: Typically shallow and occur along the fault lines due to the sliding of plates. 3. **No Significant Volcanic Activity**: - Unlike divergent and convergent boundaries, transform boundaries do not generally produce volcanic activity. **General Review Points** 1. **Interactions Between Plates**: - **Divergent Boundaries**: New crust formation and mid-ocean ridges. - **Convergent Boundaries**: Crust destruction and major geological features like trenches, volcanic arcs, and mountain ranges. - **Transform Boundaries**: Horizontal sliding of plates and faulting. 2. **Seismic Activity**: - Earthquakes occur at all boundary types, but their characteristics (depth and intensity) vary based on the boundary type and interaction. 3. **Volcanic Activity**: - Prominent at divergent (mid-ocean ridges) and convergent (subduction zones) boundaries but not typically at transform boundaries. **Earth\'s Layers** 1. **Crust**: - **Location**: Outermost layer of the Earth. - **Composition**: Mainly silicon, oxygen, aluminum, and other elements. - **Types**: - **Continental Crust**: Thicker, less dense, composed mainly of granite. - **Oceanic Crust**: Thinner, denser, composed mainly of basalt. 2. **Mantle**: - **Location**: Beneath the crust and extends to about 2,900 km deep. - **Composition**: Primarily silicon, oxygen, magnesium, and iron. - **Structure**: - **Upper Mantle**: Includes the lithosphere (rigid) and asthenosphere (more ductile). - **Lower Mantle**: More rigid than the upper mantle due to increased pressure. 3. **Outer Core**: - **Location**: Beneath the mantle, extending from about 2,900 km to 5,150 km deep. - **Composition**: Mainly iron and nickel, in a liquid state. - **Role**: Responsible for generating Earth\'s magnetic field through its movement and convection currents. 4. **Inner Core**: - **Location**: Center of the Earth, from about 5,150 km to 6,371 km deep. - **Composition**: Primarily iron and nickel. - **State**: Solid due to extremely high pressure despite very high temperatures. **Earth Internal Structures** 1. **Temperature and Pressure**: - **Increase with Depth**: Both temperature and pressure increase as you move from the crust to the core. - **Pressure Effect**: High pressure in the inner core keeps it solid even at high temperatures. 2. **Earth\'s Magnetic Field**: - **Generated**: By the movement of the liquid iron and nickel in the outer core. - **Importance**: Protects Earth from harmful solar radiation and helps with navigation. 3. **Seismic Waves**: - **P-Waves** (Primary Waves): Travel through both solid and liquid; provide evidence of the outer core\'s liquid state. - **S-Waves** (Secondary Waves): Only travel through solids; their absence in the outer core supports its liquid state. 4. **Rock Types**: - **Crust**: Contains igneous, sedimentary, and metamorphic rocks. - **Mantle**: Mostly made of peridotite, an ultramafic rock. 5. **Layer Thickness**: - **Crust**: Thinnest layer. - **Mantle**: Thickest layer. - **Core**: Divided into outer (liquid) and inner (solid) core **Mantle Convection** 1. **Process**: - Mantle convection involves the movement of hot, molten rock in the Earth\'s mantle. - Hot material rises towards the Earth\'s surface, cools, and then sinks back down, creating convection currents. 2. **Impact on Plate Movement**: - These convection currents drive the movement of tectonic plates on the Earth\'s surface. - Rising hot material can cause plates to move apart (divergent boundaries). - Sinking cooler material can pull plates down into the mantle (subduction). **Ridge Push** 1. **Mechanism**: - Ridge push occurs at mid-ocean ridges, where new oceanic crust is formed. - The rising magma creates a high, elevated ridge. - The force of gravity pushes the new, elevated crust away from the ridge, causing tectonic plates to move apart. 2. **Features**: - Mid-ocean ridges, such as the Mid-Atlantic Ridge. - Results in the creation of new oceanic crust and the expansion of ocean basins. **Slab Pull** 1. **Mechanism**: - Slab pull is the force exerted by a subducting tectonic plate as it sinks into the mantle. - The weight of the subducting slab pulls the rest of the plate along with it. 2. **Features**: - Subduction zones, where one plate is forced beneath another. - Deep ocean trenches and volcanic arcs are often associated with slab pull forces. **Plate Boundaries and Interactions** 1. **Divergent Boundaries**: - Plates move away from each other. - Features include mid-ocean ridges and rift valleys. - Associated with mantle convection and ridge push. 2. **Convergent Boundaries**: - Plates move towards each other. - Features include subduction zones, mountain ranges, and volcanic arcs. - Associated with slab pull and mantle convection. 3. **Transform Boundaries**: - Plates slide past each other horizontally. - Features include fault lines and earthquake activity. - Not directly associated with ridge push or slab pull. **General Concepts** 1. **Interaction of Forces**: - **Ridge Push**: Pushes plates away from mid-ocean ridges. - **Slab Pull**: Pulls plates down into subduction zones. - **Mantle Convection**: Drives the overall movement of tectonic plates. 2. **Geological Consequences**: - **Earthquakes**: Occur at all types of plate boundaries but are most common at transform boundaries. - **Volcanic Activity**: Common at divergent and convergent boundaries. - **Mountain Building**: Occurs at convergent boundaries where plates collide. **Continental Drift Evidence** 1. **Matching Geological Formations**: - **Rock Types**: Similar rock formations are found on continents that are now separated by oceans. - **Mountain Ranges**: Mountain ranges such as the Appalachian Mountains in North America and the Caledonian Mountains in Europe and Scandinavia align when continents are reconstructed. 2. **Fossil Evidence**: - **Similar Fossils**: Identical or similar fossils (e.g., Mesosaurus, Glossopteris) are found on continents that are now separated by oceans, suggesting they were once connected. 3. **Paleoclimatic Evidence**: - **Glacial Deposits**: Evidence of ancient glacial deposits in regions that are now tropical indicates that these regions were once situated closer to the poles. **2. Mid-Ocean Ridges** 1. **New Oceanic Crust Formation**: - **Ridge Push**: At mid-ocean ridges, magma rises to create new oceanic crust, pushing plates apart. - **Symmetrical Magnetic Stripes**: Magnetic anomalies on either side of mid-ocean ridges show symmetrical patterns, supporting the idea of sea-floor spreading. **3. Earthquake Patterns** 1. **Distribution of Epicenters**: - **Plate Boundaries**: Earthquakes frequently occur along plate boundaries, providing evidence of plate movement and interaction. **4. Ancient Glacial Deposits** 1. **Distribution of Deposits**: - **Past Ice Sheets**: Evidence of ancient glacial deposits and striations found on now-tropical continents suggests they were once closer to the poles. **5. Rock Formations Across Continents** 1. **Matching Rock Layers**: - **Rock Types and Ages**: Similar rock types and ages found on different continents suggest they were once connected. **6. Paleomagnetic Evidence** 1. **Magnetic Stripes on Ocean Floor**: - **Magnetic Reversals**: Symmetrical patterns of magnetic stripes on the ocean floor, matching the Earth\'s magnetic reversals, support the theory of sea-floor spreading. **7. Sedimentary Evidence** 1. **Sediment Layers**: - **Consistency Across Continents**: Similar sedimentary layers and rock formations across different continents indicate that they were once joined. **8. Satellite Technology** 1. **Real-Time Plate Movement**: - **Plate Tracking**: Modern satellite technology provides real-time measurements of plate movement, helping to validate the theory of plate tectonics.