Topic 1, 2, 5 & 6 Glossary: Tectonics, Coasts, Water, and Carbon Cycles

Internal Structure & Plate Tectonics

• Lithosphere: Comprises the crust and the uppermost portion of the mantle. It is characterized as a solid layer that is fragmented into distinct tectonic plates.
• Asthenosphere: The semi-molten (plastic) layer of the mantle situated directly beneath the lithosphere. The tectonic plates essentially "float" and move upon this layer.
• Convection Currents: A mechanism driven by heat rising from the Earth's core. This heat creates circular motion within the mantle, which acts to drag the overlying tectonic plates.
• Slab Pull: Recognized as the primary driving force behind plate motion. In this process, cold and dense oceanic plates sink into the mantle at subduction zones, dragging the remainder of the plate behind them.
• Sea-floor Spreading: A phenomenon occurring at mid-ocean ridges where plates diverge, allowing magma to rise to the surface and cool, thereby creating new oceanic crust.

Plate Boundaries and Tectonic Zones

• Constructive (Divergent) Boundaries: Occur when plates move away from each other. An example is the Mid-Atlantic Ridge. These zones typically produce shield volcanoes and relatively minor earthquakes.
• Destructive (Convergent) Boundaries: Occur when plates move toward one another. This includes two main sub-types:     * Subduction: An oceanic plate (denser) sinks beneath a continental plate (less dense). This results in deep ocean trenches and highly explosive volcanoes, such as those found in The Andes.     * Collision: Two continental plates of similar density smash together. Neither subducts, resulting in the upward thrusting of land to create Fold Mountains, such as The Himalayas.
• Conservative (Transform) Boundaries: Occur when plates slide laterally past each other. An example is the San Andreas Fault. While no volcanoes are formed at these boundaries, they are sites of high-magnitude, violent earthquakes.

Earthquake and Volcano Mechanics

• Hypocentre (Focus): The precise point located deep underground where the rock fracture initiates the earthquake.
• Epicentre: The point on the Earth's surface located vertically above the hypocentre.
• Benioff Zone: A specific area within a subducting plate where the friction and pressure between the two plates generate deep-seated, high-energy earthquakes.
• Magma Viscosity: Refers to the thickness or stickiness of the magma.     * High Viscosity (Andesitic): Leads to explosive eruptions as gas cannot easily escape.     * Low Viscosity (Basaltic): Leads to runny, fluid lava flows.
• Pyroclastic Flow: A lethal volcanic hazard composed of a fast-moving, super-heated cloud of ash, gas, and rock fragments.
• Lahar: A volcanic mudflow that occurs when volcanic ash mixes with water from melting ice or intense rainfall.

Measuring Tectonic Hazards

• Moment Magnitude Scale ($M_w$): A logarithmic scale used to measure the total energy released by an earthquake. It has superseded the Richter scale in modern seismology.
• Mercalli Scale: A qualitative scale that measures the intensity and observed damage of an earthquake based on human perception and physical impact on structures.
• Volcanic Explosivity Index (VEI): A scale ranging from $0$ to $8$ that measures the magnitude of a volcanic eruption based on the volume of material ejected and the height of the eruption cloud.
• Hazard Profile: A graphical tool used to compare and contrast the characteristics of different hazards, including magnitude, speed of onset, and duration.

Vulnerability, Resilience, and Risk Models

• Vulnerability: The degree to which a population is susceptible to the negative impacts of a hazard. Common factors include poverty levels, building quality, and the age of the population.
• Resilience: The capacity of a community or society to "bounce back" and recover effectively following a disaster.
• The Degg Model: A conceptual Venn diagram illustrating that a disaster occurs only at the intersection of a physical hazard and a vulnerable population.
• Governance: The efficiency and quality of a country’s administration. High-quality governance (e.g., Japan) correlates with stricter building codes and effective early warning systems.
• Pressure and Release (PAR) Model: A diagnostic tool used to trace how "root causes" (e.g., national debt) manifest as "dynamic pressures" that lead to "unsafe conditions" (e.g., poor local infrastructure), which then turn a hazard into a disaster.

Hazard Management and Strategies

• Mitigation: Actions designed to reduce the severity or impact of a hazard before it occurs, such as constructing earthquake-proof buildings.
• Adaptation: Strategies focused on changing human behaviors and lifestyles to live safely with hazards, such as conducting regular evacuation drills.
• Hazard Management Cycle: A framework consisting of four recurring stages: Mitigation $\rightarrow$ Preparation $\rightarrow$ Response $\rightarrow$ Recovery.
• Park Model (Disaster Response Curve): A graph depicting the fluctuation in the quality of life following a disaster. It tracks the time taken for a community to return to "normal" or achieve a state that is "better than before."
• Exam Strategy Insight: Examiners frequently focus on "Vulnerability." Always link physical hazards (e.g., a $7.0$ earthquake) to the human context (e.g., high-density slums). For example, Haiti's high vulnerability was caused by poor governance and unsafe conditions, transforming a $7.0$ magnitude quake into a catastrophic disaster.

Geomorphic Marine Processes

• Marine Erosion:     * Hydraulic Action: Water from waves forces air into cracks in the rock. The air is compressed and then expands as the wave retreats, causing the rock to shatter.     * Corrasion (Abrasion): The mechanical grinding of the cliff base by waves hurling pebbles and rocks against it, similar to sandpaper.     * Attrition: A process where rocks carried by the sea collide with each other, becoming progressively smaller, smoother, and rounder.     * Corrosion (Solution): The chemical dissolution of carbonate rocks (e.g., limestone) by the weak acids found in seawater.
• Weathering (Sub-aerial):     * Freeze-Thaw: Water enters rock cracks and freezes. When water freezes, it expands by $9\%$, exerting internal pressure that eventually breaks the rock apart. Most common in cold or temperate climates.     * Salt Crystallisation: Seawater evaporates within rock pores, leaving behind salt crystals that grow and exert pressure on the structure. This is most prevalent in the "splash zone."
• Mass Movement: The downslope transfer of material under the influence of gravity, such as rotational slumping on clay-rich cliffs.

Geology and Cliff Profiles

• Lithology: Refers to the physical and chemical characteristics of rock, including its mineral composition, hardness, and porosity.
• Concordant Coast: A coastline where the rock strata run parallel to the shore. These often result in landforms like Lulworth Cove.
• Discordant Coast: A coastline where rock strata run perpendicular (at right angles) to the shore. This variation in rock resistance leads to the formation of Headlands and Bays.
• Joints and Faults: Geological "weaknesses." Faults represent major fractures in the rock, while joints are smaller, more regular cracks.
• Dip: The angle at which rock layers are tilted.     * Seaward Dip: Features a high risk of landslides and slumping.     * Landward Dip: Generally more stable, contributing to the formation of steeper cliffs.

Marine Systems and Waves

• Fetch: The distance of open water across which the wind blows to generate waves. A longer fetch results in larger, more powerful waves.
• Constructive Waves: Waves with a low frequency, a strong swash, and a weak backwash. They tend to build up beaches by depositing sediment.
• Destructive Waves: Waves with a high frequency, a weak swash, and a strong backwash. They erode beaches by removing sediment.
• Longshore Drift (LSD): The lateral movement of sediment along a coast in a zigzag pattern, governed by the angle of the prevailing wind.
• Dynamic Equilibrium: Relative stability in a coastal system where the rates of erosion and deposition are balanced.

Coastal Landforms

• Spit: A narrow, elongated ridge of sand or shingle that is attached to the mainland at one end and extends into the sea (e.g., Spurn Head).
• Tombolo: A spit that has extended far enough to connect an offshore island to the mainland (e.g., Chesil Beach).
• Cuspate Foreland: A triangular accumulation of sand and sediment formed by the convergence of longshore drift from two directions (e.g., Dungeness).
• Wave-Cut Platform: A flat, rocky area found at the base of a cliff, created as the cliff retreats inland due to erosion.

Sea Level Change and Coastal Landforms

• Eustatic Change: A global change in sea level, often caused by the melting of ice caps or thermal expansion of the oceans.
• Isostatic Change: A local change in land level. This involves "isostatic rebound," where land rises after the weight of ice age glaciers is removed, causing a relative fall in sea level.
• Emergent Landforms: Created when sea levels fall relative to the land, such as Raised Beaches.
• Submergent Landforms: Created when sea levels rise relative to the land. Examples include:     * Rias: Drowned river valleys.     * Fjords: Drowned glacial valleys.

Coastal Management Strategies

• Hard Engineering: High-cost, man-made structures designed to provide a physical barrier against the sea (e.g., Groynes, Sea Walls, Rip Rap).
• Soft Engineering: Low-cost, naturalistic approaches that work with coastal processes (e.g., Beach Nourishment, Dune Stabilisation).
• Managed Realignment: The deliberate policy of allowing the sea to flood low-value land, thereby creating a natural buffer to protect high-value areas.
• ICZM (Integrated Coastal Zone Management): A holistic approach to coastal management that considers the entire coastline rather than isolated sections.
• SMP (Shoreline Management Plan): A strategic document that defines the management policy for a stretch of coast: "Hold the Line," "Advance the Line," "Managed Realignment," or "Do Nothing."

Comprehensive List of Sub-aerial Processes

• Chemical Weathering:     * Carbonation: Rainwater reacts with atmospheric $CO_2$ to form weak carbonic acid. This acid dissolves calcium carbonate in rocks like Limestone and Chalk.     * Oxidation: Oxygen reacts with iron minerals in rocks to form iron oxide (rust), causing the rock to disintegrate. This often leaves red or orange stains.     * Hydrolysis: Chemical reaction between water and minerals such as feldspar (found in granite), which converts them into clay and weakens the rock.
• Biological Weathering:     * Root Wedging: Plant roots penetrate joints and cracks, expanding as they grow and prying the rock apart.     * Boring: Marine organisms like Piddocks (molluscs) or sea urchins drill into rocks to create habitats, structurally weakening the cliff.
• Specific Mass Movement Types:     * Rockfall: Rapid vertical movement where rock fragments (often loosened by freeze-thaw) fall to the base of the cliff, forming a Talus Slope (scree).     * Rotational Slumping: Movement of saturated soil or weak rock (like clay) down a curved slip plane. This results in a "stepped" profile on the cliff face.     * Landslide: Rapid movement of earth or rock down a linear/flat slip plane, often facilitated by bedding planes dipping toward the sea.     * Mudflow: Occurs when fine-grained sediment becomes saturated and flows downslope as a liquid.

High-Level Technical Coastal Terms

• Littoral Zone: The wider coastal area consisting of the land near the shore and shallow offshore waters. It is divided into: Backshore, Foreshore, Nearshore, and Offshore.
• Morphology: The specific shape and form of the coastal landscape (e.g., "steep cliff morphology").
• Pore Water Pressure: The pressure exerted by water within the gaps of soil or rock. High pore water pressure is a frequent trigger for slumping.
• Unconsolidated Sediment: Loose material (e.g., sand or Boulder Clay) that has not been lithified. It erodes extremely quickly (e.g., Holderness Coast).
• Sediment Cell: A self-contained section of the coast where sediment movement is largely internal. England and Wales have $11$ major cells.
• Coastal Squeeze: The disappearance of coastal ecosystems (like salt marshes) when they are trapped between rising sea levels and immovable man-made sea walls.

The Global Hydrological Cycle

• Closed System: The Earth's global water cycle is a closed system because it has a fixed amount of water; no water enters or leaves the planet.
• Open System: A drainage basin is considered an open system because water enters (precipitation) and leaves (evapotranspiration/runoff) the cycle.
• Fluxes: The transfer mechanisms/movement of water between stores (e.g., precipitation, evaporation).
• Residence Time: The average duration water remains in a specific store (e.g., thousands of years in ice caps vs. approximately $9$ days in the atmosphere).
• Cryosphere: The collective term for the frozen water on Earth, including glaciers, ice caps, and permafrost.

Drainage Basin Dynamics

• Watershed: The elevated ridge or boundary that divides one drainage basin from another.
• Precipitation: Water in any form (rain, snow, sleet) falling from the atmosphere to the Earth's surface.
• Interception: The process where vegetation or trees catch precipitation before it reaches the soil.
• Infiltration: The vertical movement of water into the soil surface.
• Percolation: The deeper vertical movement of water from the soil into underground rock layers (aquifers).
• Throughflow: The lateral (sideways) movement of water through the soil layer.
• Groundwater Flow: The very slow movement of water through rock towards a river or ocean.
• Evapotranspiration: The total amount of water transferred to the atmosphere from surfaces (evaporation) and through plant leaves (transpiration).

Climate Extremes: Drought and Floods

• Anticyclone: A high-pressure system that brings stable, dry weather; it is a primary cause of Meteorological Drought.
• ITCZ (Inter-Tropical Convergence Zone): A low-pressure belt near the equator that produces heavy rainfall. Failure of the ITCZ to move can cause severe droughts in regions like the Sahel.
• El Nio: A climate event where Pacific trade winds weaken or reverse, causing drought in Australia and heavy rain in South America.
• La Nia: The intensification of normal conditions, leading to extreme dryness in South America and extreme wetness in Australia.
• Ecosystem Resilience: The capacity of a biological environment (like a wetland) to recover from extreme events like droughts or floods.

Water Insecurity and Scarcity

• Water Stress: Defined as having less than $1,700\,m^3$ of water available per person per year.
• Water Scarcity: Defined as having less than $1,000\,m^3$ of water available per person per year.
• Physical Scarcity: A situation where there is a literal lack of water resources (e.g., arid deserts).
• Economic Scarcity: A situation where water exists, but a lack of financial resources prevents the development of infrastructure to access it (common in Sub-Saharan Africa).
• The Water Gap: The growing disparity between the increasing global demand for water and the diminishing supply.

Water Management and Geopolitics

• Trans-boundary Water: Water sources (rivers or aquifers) that cross one or more national borders (e.g., the River Nile).
• Asymmetric Power: A geopolitical situation where one country (often upstream) exerts dominant control over a water source relative to its neighbors (e.g., China's control of the Mekong).
• Water Privatisation: The ownership and management of water supplies by private corporations rather than government entities.
• Smart Irrigation: The use of technology, such as drip pipes, to maximize water efficiency in agriculture.
• Integrated Drainage Basin Management (IDBM): A cooperative management strategy involving all stakeholders and countries along a river to ensure sustainable use and prevent conflict.

The Carbon Cycle

• Carbon Store / Sink: A reservoir where carbon is accumulated and held. The Lithosphere is the largest global carbon store.
• Carbon Flux: The transfer of carbon between different stores. An example is Photosynthesis, which moves carbon from the atmosphere to the biosphere.
• Outgassing: The release of $CO_2$ into the atmosphere, occurring through volcanic activity or as oceans warm.
• Sequestration: The long-term capture and storage of carbon in terrestrial plants, soils, or geological formations.
• Carbon Neutral: Achieving a state where the amount of $CO_2$ released is exactly balanced by the amount sequestered.
• Biological Pump: A marine process where phytoplankton consume $CO_2$. When they die, they sink to the ocean floor, effectively "pumping" carbon into the deep ocean.

Terrestrial and Marine Carbon Systems

• Photosynthesis: The process by which plants absorb $CO_2$ to produce glucose, also known as Primary Productivity.
• Respiration: The process by which living organisms release $CO_2$ back into the atmosphere.
• Decomposition: The organic breakdown of matter that releases carbon into the soil.
• Humus: The carbon-rich, dark organic component of soil formed by the decomposition of plant and animal matter.
• Phytoplankton: Microscopic marine plants that form the base of the ocean's food web and carbon cycle.
• Carbonate Rocks: Sedimentary rocks like Limestone formed from the calcified remains of marine organisms; these serve as massive long-term carbon stores.

Climate Feedback Loops

• The Greenhouse Effect: The natural process by which specific atmospheric gases trap heat, maintaining Earth's temperature.
• Anthropogenic: Refers to processes or materials derived from human activities (e.g., anthropogenic emissions).
• Positive Feedback: A self-reinforcing cycle that amplifies change. (Example: Permafrost melts $\rightarrow$ Methane is released $\rightarrow$ Warming increases $\rightarrow$ More permafrost melts).
• Negative Feedback: A self-regulating cycle that stabilizes a system. (Example: Higher $CO_2$ $\rightarrow$ Increased plant growth $\rightarrow$ More $CO_2$ absorbed $\rightarrow$ Global warming slows down).
• Ocean Acidification: Occurs when the ocean absorbs excess $CO_2$, causing the $pH$ to drop. This dissolves the calcium carbonate shells of marine life and disrupts the biological pump.

Energy Security and Global Consumption

• Energy Security: The availability of a continuous, reliable supply of energy at an affordable price.
• Energy Mix: The specific combination of different energy sources used by a nation (e.g., fossil fuels, renewables, nuclear).
• Primary Energy: Natural resources that have not been converted into another form of energy (e.g., crude oil, coal, wind).
• Secondary Energy: Energy that has been processed into a more convenient form, such as Electricity.
• Energy Pathway: The physical route energy takes from the producer to the consumer, such as pipelines, shipping lanes, or transmission lines.
• Energy Poverty: A condition where a household lacks the financial means to access essential energy services like heating or power.

Energy Sources and Key Players

• Fossil Fuels: Non-renewable carbon-based resources such as coal, oil, and natural gas.
• TNCs (Transnational Corporations): Major global companies (e.g., Shell, BP) involved in the exploration, extraction, and trade of energy resources.
• OPEC (Organization of the Petroleum Exporting Countries): An intergovernmental organization of $13$ oil-exporting nations that coordinates petroleum policies and prices.
• Renewables: Energy sources that are naturally replenished (Solar, Wind, Hydro-Electric Power).
• Recyclable Energy: Refers to nuclear power, as the uranium fuel can be reprocessed for further use.
• Biofuels: Fuels derived from organic matter (e.g., ethanol produced from corn).
• Fracking (Hydraulic Fracturing): A technique for extracting shale gas by injecting water and chemicals into rock at high pressure to fracture the stone.

Geopolitics of Energy

• Transit State: A country through which energy (typically gas or oil) must pass via pipeline to reach its final destination (e.g., Ukraine as a transit state for Russian gas).
• Chokepoint: A narrow, strategic geographic passage (e.g., the Strait of Hormuz) where energy supplies are highly susceptible to blockage or military conflict.
• Carbon Capture and Storage (CCS): A technology designed to capture $CO_2$ emissions from industrial sources and pump them deep underground for permanent storage.
• Strategic Reserve: Emergency stockpiles of fuel maintained by a country to ensure stability during supply disruptions (e.g., the US Strategic Petroleum Reserve).