Barron's

Plate tectonic theory

Earth's lithosphere is divided into plates that move over the mantle, causing seismic activity at their boundaries.

Continental drift theory

Proposed by Wegener, it suggests all continents originated from Pangaea and broke apart, supported by fossil and landscape evidence.

Seafloor spreading theory

Describes volcanic rift zones that indicate subduction zones.

Convergent boundaries

Areas where two tectonic plates slide toward each other, forming subduction zones, mountains, or oceanic trenches.

Divergent boundaries

Locations where two plates move apart, filled with molten magma, creating oceanic ridges or rift valleys.

Oceanic divergent boundary

Example is the Mid-Atlantic Ridge.

Continental divergent boundary

Example is the East African Great Rift Valley.

Island arc

Volcanic islands formed by converging oceanic plates through subduction.

Transform boundaries

Areas where plates slide past each other, causing friction and stress, exemplified by the San Andreas fault.

Soil

A thin layer on Earth's surface that influences water chemistry, holds nutrients, and filters water.

Soil composition

Made up of minerals, air, water, and organic materials.

Loam

Ideal soil for plants, consisting of 45% minerals, 5% organic matter, 25% air, and 25% water.

Soil profile

Layers of soil including O, A, E, B, and C horizons, each with distinct characteristics.

Soil erosion

Movement of weathered rock and soil by water, wind, or human activity, leading to reduced water-holding capacity.

Landslides

Masses of rock and debris moving down slopes, often triggered by heavy rains or earthquakes.

Mudslides

Fast-moving landslides that flow in channels, often occurring on steep slopes.

Igneous rock

Formed from cooling magma, classified as intrusive or extrusive based on where they solidify.

Metamorphic rock

Created under intense heat and pressure, examples include gneiss and marble.

Sedimentary rock

Formed from the accumulation and cementation of materials, often containing fossils.

Soil texture

The relative abundance of sand, silt, and clay in soil.

Gravel

Coarse soil particles made of rock fragments.

Sand

Coarser than silt, allows water to flow through quickly, suitable for certain crops.

Silt

Fine particles easily transported by water, between sand and clay in size.

Clay

Very fine particles that compact easily and have low permeability to water.

Humus

Dark organic material in soil formed from decayed plant and animal matter.

Soil quality

Refers to aeration, compaction, nutrient-holding capacity, permeability, and pH.

Greenhouse effect

Warming of Earth's surface due to greenhouse gases trapping heat in the atmosphere.

Trade winds

Prevailing easterly winds found in the tropics near the equator.

Coriolis effect

The deflection of winds due to Earth's rotation, affecting wind patterns.

Hadley cells

Circulation cells where warm air rises at the equator and sinks in subtropical regions.

Polar vortex

A low-pressure zone of cold air over the poles, influencing weather patterns.

Hurricanes

Severe weather systems formed over warm oceans, characterized by strong winds and heavy rainfall.

Tornadoes

Violent windstorms with rotating columns of air, formed from convective storms.

Monsoons

Seasonal winds that change direction, bringing heavy rainfall in summer and dry conditions in winter.

Watershed

An area of land that drains water into a specific body of water or underground reservoirs.

Watershed management

Practices aimed at protecting and managing land and water resources sustainably.

Solar intensity

Affected by Earth's axial tilt, atmospheric conditions, and distance from the sun.

Climate

Long-term patterns of temperature and precipitation in a specific region.

Weather

Short-term atmospheric conditions in a specific area.

El Niño

A warm phase characterized by reversed air pressure patterns and decreased upwelling in the Pacific.

La Niña

A cool phase with strong westerlies, increased upwelling, and cooler sea surface temperatures.