Earth's Structure & Plate Tectonics

• Geography is the study of the Earth's surface, encompassing its physical features, human populations, and the interactions between them
• Physical geography focuses on the natural processes and features of the Earth

Earth's Structure and Composition

• The Earth consists of several layers consisting of the crust, mantle, outer core, and inner core
• The crust, the outermost solid layer, is divided into continental and oceanic crust
• The mantle is a semi-solid layer beneath the crust, making up most of the Earth's volume
• The outer core is a liquid layer composed mainly of iron and nickel
• The inner core is a solid sphere also composed mainly of iron and nickel, under immense pressure

Plate Tectonics

• The Earth's lithosphere is divided into tectonic plates that float on the asthenosphere
• Plate boundaries are where most geological activity, such as earthquakes and volcanoes, occur
• Divergent boundaries occur where plates move apart, creating new crust
• Convergent boundaries occur where plates collide, resulting in subduction or mountain building
• Transform boundaries occur where plates slide past each other horizontally, causing earthquakes

Landforms and Topography

• Landforms are natural features of the Earth's surface, shaped by various processes
• Mountains are elevated landforms formed by tectonic activity, volcanic activity, or erosion
• Plains are flat or gently rolling areas of low elevation
• Plateaus are elevated flatlands with steep sides
• Valleys are depressions in the landscape, often formed by rivers or glaciers
• Deserts are arid regions with sparse vegetation due to low precipitation

Weathering and Erosion

• Weathering is the breakdown of rocks and minerals at the Earth's surface through physical or chemical processes
• Physical weathering involves the disintegration of rocks without changing their chemical composition e.g. freeze-thaw
• Chemical weathering involves the decomposition of rocks through chemical reactions e.g. acid rain
• Erosion is the removal and transportation of weathered material by agents such as water, wind, and ice
• Water erosion includes processes like rainfall impact, runoff, and stream flow
• Wind erosion is significant in arid and semi-arid regions, transporting fine particles over long distances
• Glacial erosion occurs through the movement of ice, carving out valleys and transporting large amounts of sediment

Water Cycle

• The water cycle, also known as the hydrologic cycle, is the continuous movement of water on, above, and below the surface of the Earth
• Evaporation is the process by which water changes from a liquid to a gas
• Transpiration is the release of water vapor from plants into the atmosphere
• Condensation is the process by which water vapor changes into liquid or ice, forming clouds
• Precipitation is any form of water falling from the atmosphere to the Earth's surface, such as rain, snow, sleet, or hail
• Infiltration is the process by which water seeps into the ground

Climate and Weather

• Climate is the long-term average of weather conditions in a region
• Weather is the short-term state of the atmosphere at a particular time and place
• Temperature is a measure of the warmth or coldness of an object or substance
• Precipitation includes rain, snow, sleet, and hail
• Wind is the movement of air caused by differences in air pressure
• Humidity is the amount of water vapor in the air
• Factors influencing climate include latitude, altitude, proximity to bodies of water, and ocean currents

Biomes

• A biome is a large geographic area characterized by specific climate conditions, animal populations, and plant species
• Forests are dominated by trees
• Grasslands are dominated by grasses and herbaceous plants
• Deserts are arid regions with sparse vegetation
• Tundra is a treeless region with permafrost, located in cold climates
• Aquatic biomes include freshwater and marine environments

Soils

• Soil is a mixture of mineral particles, organic matter, water, and air that forms on the Earth's surface
• Soil formation is influenced by factors such as climate, parent material, topography, organisms, and time
• Soil texture refers to the proportion of sand, silt, and clay particles in the soil
• Soil structure refers to the arrangement of soil particles into aggregates or peds
• Soil horizons are distinct layers in the soil profile, each with unique characteristics
• Soil is important for plant growth, water storage, and nutrient cycling

Coastal Processes

• Coastal processes shape the land along coastlines through erosion, deposition, and tectonic activity
• Waves are generated by wind and transfer energy to the shore
• Tides are the periodic rise and fall of sea level caused by the gravitational forces of the Moon and Sun
• Currents are the continuous movement of seawater in a specific direction
• Beach erosion is the removal of sand and sediment from beaches, often caused by storms and rising sea levels
• Coastal deposition is the accumulation of sediment along coastlines, forming beaches, sandbars, and spits

Glaciers and Ice Sheets

• Glaciers are large masses of ice that move slowly over land
• Ice sheets are continental-sized glaciers that cover vast areas
• Glacial erosion carves out valleys and creates distinctive landforms
• Glacial deposition occurs when glaciers melt, depositing sediment and debris
• Glaciers store large amounts of freshwater, and their melting contributes to sea level rise
• Glacial landforms include U-shaped valleys, cirques, aretes, and moraines

Atmosphere

• The atmosphere is the layer of gases surrounding the Earth
• The atmosphere consists of several layers: the troposphere, stratosphere, mesosphere, thermosphere, and exosphere
• The troposphere is the lowest layer, where weather occurs
• The stratosphere contains the ozone layer, which absorbs harmful UV radiation
• The atmosphere regulates temperature, protects against radiation, and facilitates the water cycle
• Atmospheric composition includes nitrogen, oxygen, argon, and trace gases like carbon dioxide

Ecosystems

• An ecosystem is a community of living organisms interacting with each other and their physical environment
• Biotic factors are the living components of an ecosystem, such as plants, animals, and microorganisms
• Abiotic factors are the non-living components of an ecosystem, such as temperature, precipitation, and sunlight
• Food chains and food webs illustrate the flow of energy and nutrients through an ecosystem
• Biodiversity refers to the variety of life in an ecosystem or on Earth
• Ecosystem services are the benefits that humans derive from ecosystems, such as clean water, pollination, and climate regulation

Natural Hazards

• Natural hazards are natural events that can cause damage, injury, or loss of life
• Earthquakes are caused by the sudden release of energy in the Earth's crust
• Volcanoes are openings in the Earth's surface where magma, ash, and gases erupt
• Hurricanes are tropical cyclones with sustained winds of at least 74 miles per hour
• Floods occur when water overflows onto normally dry land
• Droughts are prolonged periods of abnormally low precipitation
• Landslides are the movement of rock, soil, or debris down a slope