FTCE Earth/Space Science 008 cheat sheet

Scientific method sequence: observation, hypothesis, controlled experiment or further observation, analysis, and revision; a hypothesis must be testable and falsifiable, and a theory is a well-tested explanatory framework supported by multiple independent lines of evidence.

Density = mass / volume; Earth's mean density is about 5.5 g/cm3 while surface rock averages about 2.7 g/cm3, which is direct evidence that density increases with depth toward a metallic core.

Isostasy: buoyant lithosphere floats on the asthenosphere; thicker or less dense crust rides higher, so continental crust (about 2.7 g/cm3) stands above oceanic crust (about 3.0 g/cm3).

Rock cycle decision rule: igneous forms from cooling melt, sedimentary from compaction and cementation of weathered debris or precipitates, metamorphic from heat and pressure without melting; any rock type can transform into any other.

Bowen's reaction series predicts mineral crystallization order from mafic magma: olivine and Ca-plagioclase first, then pyroxene and amphibole, then biotite, then K-feldspar, muscovite, and quartz last at lowest temperature.

Silicate tetrahedron (SiO4)4- is the building block of most crustal minerals; isolated tetrahedra give olivine, single chains give pyroxene, double chains amphibole, sheets micas and clays, frameworks quartz and feldspar.

Relative dating principles: superposition (oldest at bottom in undisturbed layers), original horizontality, lateral continuity, cross-cutting relationships (a feature cutting another is younger), and inclusions (a fragment inside a rock is older than the rock).

Unconformity types: angular (tilted layers eroded then buried), disconformity (erosion surface between parallel layers), and nonconformity (sedimentary rock over igneous or metamorphic basement).

Map and graph skills: contour lines close uphill indicate a hill, hachured contours mark depressions, contour spacing indicates slope steepness, and a topographic profile is built by plotting elevation along a transect.

Earth's interior layers by composition: crust (5-70 km), mantle (to about 2900 km), outer core (liquid iron-nickel), inner core (solid iron-nickel); by physical properties: lithosphere, asthenosphere, mesosphere, outer core, inner core.

Seismic evidence: P waves (compressional, fastest, travel through solids and liquids) refract away from the outer core, while S waves (shear, slower) cannot pass through liquid, proving the outer core is liquid; the Moho marks the crust-mantle boundary.

Plate boundary rules: divergent boundaries produce ridges, rift valleys, and shallow quakes; convergent boundaries give subduction, trenches, volcanic arcs, and deep quakes; transform boundaries give strike-slip faults and shallow quakes with no volcanism.

Seafloor spreading evidence: symmetric magnetic striping about ridges, youngest seafloor at ridge crests, age increasing outward, and matching continental margins and fossil belts across ocean basins.

Earthquake magnitude versus intensity: magnitude is a single instrumental measure of energy released (moment magnitude scale), while intensity (Mercalli) describes observed shaking and damage and decreases with distance from the epicenter.

Volcano types linked to magma: shield volcanoes from low-viscosity mafic lava (gentle slopes, Hawaii), stratovolcanoes from viscous andesitic or felsic magma (steep, explosive, Ring of Fire), and cinder cones from short-lived gas-rich eruptions.

Weathering versus erosion: weathering is in-place breakdown (mechanical such as frost wedging, chemical such as hydrolysis of feldspar to clay), erosion is transport by water, wind, ice, or gravity, and deposition follows when transport energy drops.

Stream and groundwater processes: discharge = cross-sectional area x velocity; gradient = elevation change / horizontal distance; a stream erodes fastest where velocity is highest, and groundwater flows from high hydraulic head to low, recharging where the water table intersects the surface.

Atmospheric structure and circulation: troposphere (weather, temperature decreasing with altitude), stratosphere (ozone, temperature increasing), mesosphere, thermosphere; Coriolis effect deflects winds right in the Northern Hemisphere and left in the Southern, driving global wind belts and gyres.

Relative order of geologic time: Precambrian (Hadean, Archean, Proterozoic) covers about 88% of Earth history, then Paleozoic, Mesozoic, and Cenozoic eras; periods within the Paleozoic are Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian.

Absolute dating: radiometric decay follows N = N0 e^(-lambda t) with half-life t1/2 = ln2 / lambda; after one half-life 50% of parent remains, after two 25%, after three 12.5%.

Datable materials and methods: carbon-14 (half-life about 5730 years) for organic material younger than roughly 50,000 years; potassium-argon, uranium-lead, and rubidium-strontium for older igneous and metamorphic rocks; index fossils must be widespread, abundant, and short-lived.

Fossilization requires rapid burial and hard parts; preservation types include permineralization, molds and casts, carbon films, amber and ice entrapment, and trace fossils such as footprints and burrows.

Major extinction events: end-Ordovician (glaciation), end-Devonian, end-Permian (largest, about 90% of marine species, linked to Siberian Traps volcanism), end-Triassic, and end-Cretaceous (impact at Chicxulub plus Deccan volcanism, ending non-avian dinosaurs).

Key evolutionary milestones: first life about 3.5 billion years ago (prokaryotes), oxygen-producing photosynthesis and banded iron formations, eukaryotes about 1.8 billion years ago, Cambrian explosion about 541 million years ago, land plants and vertebrates, then mammals radiating after the end-Cretaceous extinction.

Uniformitarianism: present-day processes operating over long time spans explain the rock record; catastrophism is reserved for rapid events such as impacts, floods, and eruptions that leave distinctive deposits.

Fossil succession and correlation: distinctive fossil assemblages define biostratigraphic zones, allowing correlation of separated rock layers; the principle of faunal succession states fossil content changes in a consistent order through time.

Kepler's laws: orbits are ellipses with the Sun at one focus; a planet sweeps equal areas in equal times (faster near perihelion); P^2 = a^3 when period is in years and semi-major axis in astronomical units.

Newton's law of gravitation F = G m1 m2 / r^2 explains orbital motion; escape velocity depends on mass and radius, and tidal forces arise because gravitational pull varies with distance across a body.

Earth's seasons result from axial tilt of about 23.5 degrees, not distance from the Sun; solstices mark maximum tilt toward or away from the Sun, equinoxes mark equal day and night, and perihelion occurs in early January.

Moon phases and eclipses: phases follow the Sun-Earth-Moon angle over a 29.5-day synodic month; solar eclipses occur at new moon, lunar eclipses at full moon, and eclipses are rare because the Moon's orbit is inclined about 5 degrees.

Solar system structure: terrestrial planets (Mercury, Venus, Earth, Mars) are small, dense, rocky, and close to the Sun; Jovian planets (Jupiter, Saturn, Uranus, Neptune) are large, low-density, and ringed, with icy moons and dwarf planets beyond Neptune.

Stellar classification and life cycle: spectral sequence OBAFGKM from hottest to coolest; main-sequence stars fuse hydrogen to helium, then become red giants, shed planetary nebulae, and end as white dwarfs if low mass, or supernova and leave neutron stars or black holes if high mass.

Hertzsprung-Russell diagram plots luminosity against temperature; main sequence runs diagonally, giants and supergiants sit upper right, white dwarfs lower left, and mass determines a star's position and lifetime.

Cosmology evidence: Hubble's law v = H0 d shows galaxies receding with distance, cosmic microwave background radiation is the remnant heat of the early universe, and observed light-element abundances support Big Bang nucleosynthesis; the universe is about 13.8 billion years old.

Solar system small bodies and observation: asteroids concentrate in the belt between Mars and Jupiter, comets have ion and dust tails that point away from the Sun, meteor showers come from Earth crossing comet debris trails, and telescopes are classified by aperture and by refracting or reflecting design.

Scientific method sequence: observation, hypothesis, controlled experiment or further observation, analysis, and revision; a hypothesis must be testable and falsifiable, and a theory is a well-tested explanatory framework supported by multiple independent lines of evidence.

Density = mass / volume; Earth's mean density is about 5.5 g/cm3 while surface rock averages about 2.7 g/cm3, which is direct evidence that density increases with depth toward a metallic core.

Isostasy: buoyant lithosphere floats on the asthenosphere; thicker or less dense crust rides higher, so continental crust (about 2.7 g/cm3) stands above oceanic crust (about 3.0 g/cm3).

Rock cycle decision rule: igneous forms from cooling melt, sedimentary from compaction and cementation of weathered debris or precipitates, metamorphic from heat and pressure without melting; any rock type can transform into any other.

Bowen's reaction series predicts mineral crystallization order from mafic magma: olivine and Ca-plagioclase first, then pyroxene and amphibole, then biotite, then K-feldspar, muscovite, and quartz last at lowest temperature.

Silicate tetrahedron (SiO4)4- is the building block of most crustal minerals; isolated tetrahedra give olivine, single chains give pyroxene, double chains amphibole, sheets micas and clays, frameworks quartz and feldspar.

Relative dating principles: superposition (oldest at bottom in undisturbed layers), original horizontality, lateral continuity, cross-cutting relationships (a feature cutting another is younger), and inclusions (a fragment inside a rock is older than the rock).

Unconformity types: angular (tilted layers eroded then buried), disconformity (erosion surface between parallel layers), and nonconformity (sedimentary rock over igneous or metamorphic basement).

Map and graph skills: contour lines close uphill indicate a hill, hachured contours mark depressions, contour spacing indicates slope steepness, and a topographic profile is built by plotting elevation along a transect.

Earth's interior layers by composition: crust (5-70 km), mantle (to about 2900 km), outer core (liquid iron-nickel), inner core (solid iron-nickel); by physical properties: lithosphere, asthenosphere, mesosphere, outer core, inner core.

Seismic evidence: P waves (compressional, fastest, travel through solids and liquids) refract away from the outer core, while S waves (shear, slower) cannot pass through liquid, proving the outer core is liquid; the Moho marks the crust-mantle boundary.

Plate boundary rules: divergent boundaries produce ridges, rift valleys, and shallow quakes; convergent boundaries give subduction, trenches, volcanic arcs, and deep quakes; transform boundaries give strike-slip faults and shallow quakes with no volcanism.

Seafloor spreading evidence: symmetric magnetic striping about ridges, youngest seafloor at ridge crests, age increasing outward, and matching continental margins and fossil belts across ocean basins.

Earthquake magnitude versus intensity: magnitude is a single instrumental measure of energy released (moment magnitude scale), while intensity (Mercalli) describes observed shaking and damage and decreases with distance from the epicenter.

Volcano types linked to magma: shield volcanoes from low-viscosity mafic lava (gentle slopes, Hawaii), stratovolcanoes from viscous andesitic or felsic magma (steep, explosive, Ring of Fire), and cinder cones from short-lived gas-rich eruptions.

Weathering versus erosion: weathering is in-place breakdown (mechanical such as frost wedging, chemical such as hydrolysis of feldspar to clay), erosion is transport by water, wind, ice, or gravity, and deposition follows when transport energy drops.

Stream and groundwater processes: discharge = cross-sectional area x velocity; gradient = elevation change / horizontal distance; a stream erodes fastest where velocity is highest, and groundwater flows from high hydraulic head to low, recharging where the water table intersects the surface.

Atmospheric structure and circulation: troposphere (weather, temperature decreasing with altitude), stratosphere (ozone, temperature increasing), mesosphere, thermosphere; Coriolis effect deflects winds right in the Northern Hemisphere and left in the Southern, driving global wind belts and gyres.

Relative order of geologic time: Precambrian (Hadean, Archean, Proterozoic) covers about 88% of Earth history, then Paleozoic, Mesozoic, and Cenozoic eras; periods within the Paleozoic are Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian.

Absolute dating: radiometric decay follows N = N0 e^(-lambda t) with half-life t1/2 = ln2 / lambda; after one half-life 50% of parent remains, after two 25%, after three 12.5%.

Datable materials and methods: carbon-14 (half-life about 5730 years) for organic material younger than roughly 50,000 years; potassium-argon, uranium-lead, and rubidium-strontium for older igneous and metamorphic rocks; index fossils must be widespread, abundant, and short-lived.

Fossilization requires rapid burial and hard parts; preservation types include permineralization, molds and casts, carbon films, amber and ice entrapment, and trace fossils such as footprints and burrows.

Major extinction events: end-Ordovician (glaciation), end-Devonian, end-Permian (largest, about 90% of marine species, linked to Siberian Traps volcanism), end-Triassic, and end-Cretaceous (impact at Chicxulub plus Deccan volcanism, ending non-avian dinosaurs).

Key evolutionary milestones: first life about 3.5 billion years ago (prokaryotes), oxygen-producing photosynthesis and banded iron formations, eukaryotes about 1.8 billion years ago, Cambrian explosion about 541 million years ago, land plants and vertebrates, then mammals radiating after the end-Cretaceous extinction.

Uniformitarianism: present-day processes operating over long time spans explain the rock record; catastrophism is reserved for rapid events such as impacts, floods, and eruptions that leave distinctive deposits.

Fossil succession and correlation: distinctive fossil assemblages define biostratigraphic zones, allowing correlation of separated rock layers; the principle of faunal succession states fossil content changes in a consistent order through time.

Kepler's laws: orbits are ellipses with the Sun at one focus; a planet sweeps equal areas in equal times (faster near perihelion); P^2 = a^3 when period is in years and semi-major axis in astronomical units.

Newton's law of gravitation F = G m1 m2 / r^2 explains orbital motion; escape velocity depends on mass and radius, and tidal forces arise because gravitational pull varies with distance across a body.

Earth's seasons result from axial tilt of about 23.5 degrees, not distance from the Sun; solstices mark maximum tilt toward or away from the Sun, equinoxes mark equal day and night, and perihelion occurs in early January.

Moon phases and eclipses: phases follow the Sun-Earth-Moon angle over a 29.5-day synodic month; solar eclipses occur at new moon, lunar eclipses at full moon, and eclipses are rare because the Moon's orbit is inclined about 5 degrees.

Solar system structure: terrestrial planets (Mercury, Venus, Earth, Mars) are small, dense, rocky, and close to the Sun; Jovian planets (Jupiter, Saturn, Uranus, Neptune) are large, low-density, and ringed, with icy moons and dwarf planets beyond Neptune.

Stellar classification and life cycle: spectral sequence OBAFGKM from hottest to coolest; main-sequence stars fuse hydrogen to helium, then become red giants, shed planetary nebulae, and end as white dwarfs if low mass, or supernova and leave neutron stars or black holes if high mass.

Hertzsprung-Russell diagram plots luminosity against temperature; main sequence runs diagonally, giants and supergiants sit upper right, white dwarfs lower left, and mass determines a star's position and lifetime.

Cosmology evidence: Hubble's law v = H0 d shows galaxies receding with distance, cosmic microwave background radiation is the remnant heat of the early universe, and observed light-element abundances support Big Bang nucleosynthesis; the universe is about 13.8 billion years old.

Solar system small bodies and observation: asteroids concentrate in the belt between Mars and Jupiter, comets have ion and dust tails that point away from the Sun, meteor showers come from Earth crossing comet debris trails, and telescopes are classified by aperture and by refracting or reflecting design.

Scientific method sequence: observation, hypothesis, controlled experiment or further observation, analysis, and revision; a hypothesis must be testable and falsifiable, and a theory is a well-tested explanatory framework supported by multiple independent lines of evidence.

Density = mass / volume; Earth's mean density is about 5.5 g/cm3 while surface rock averages about 2.7 g/cm3, which is direct evidence that density increases with depth toward a metallic core.

Isostasy: buoyant lithosphere floats on the asthenosphere; thicker or less dense crust rides higher, so continental crust (about 2.7 g/cm3) stands above oceanic crust (about 3.0 g/cm3).

Rock cycle decision rule: igneous forms from cooling melt, sedimentary from compaction and cementation of weathered debris or precipitates, metamorphic from heat and pressure without melting; any rock type can transform into any other.

Bowen's reaction series predicts mineral crystallization order from mafic magma: olivine and Ca-plagioclase first, then pyroxene and amphibole, then biotite, then K-feldspar, muscovite, and quartz last at lowest temperature.

Silicate tetrahedron (SiO4)4- is the building block of most crustal minerals; isolated tetrahedra give olivine, single chains give pyroxene, double chains amphibole, sheets micas and clays, frameworks quartz and feldspar.

Relative dating principles: superposition (oldest at bottom in undisturbed layers), original horizontality, lateral continuity, cross-cutting relationships (a feature cutting another is younger), and inclusions (a fragment inside a rock is older than the rock).

Unconformity types: angular (tilted layers eroded then buried), disconformity (erosion surface between parallel layers), and nonconformity (sedimentary rock over igneous or metamorphic basement).

Map and graph skills: contour lines close uphill indicate a hill, hachured contours mark depressions, contour spacing indicates slope steepness, and a topographic profile is built by plotting elevation along a transect.

Earth's interior layers by composition: crust (5-70 km), mantle (to about 2900 km), outer core (liquid iron-nickel), inner core (solid iron-nickel); by physical properties: lithosphere, asthenosphere, mesosphere, outer core, inner core.

Seismic evidence: P waves (compressional, fastest, travel through solids and liquids) refract away from the outer core, while S waves (shear, slower) cannot pass through liquid, proving the outer core is liquid; the Moho marks the crust-mantle boundary.

Plate boundary rules: divergent boundaries produce ridges, rift valleys, and shallow quakes; convergent boundaries give subduction, trenches, volcanic arcs, and deep quakes; transform boundaries give strike-slip faults and shallow quakes with no volcanism.

Seafloor spreading evidence: symmetric magnetic striping about ridges, youngest seafloor at ridge crests, age increasing outward, and matching continental margins and fossil belts across ocean basins.

Earthquake magnitude versus intensity: magnitude is a single instrumental measure of energy released (moment magnitude scale), while intensity (Mercalli) describes observed shaking and damage and decreases with distance from the epicenter.

Volcano types linked to magma: shield volcanoes from low-viscosity mafic lava (gentle slopes, Hawaii), stratovolcanoes from viscous andesitic or felsic magma (steep, explosive, Ring of Fire), and cinder cones from short-lived gas-rich eruptions.

Weathering versus erosion: weathering is in-place breakdown (mechanical such as frost wedging, chemical such as hydrolysis of feldspar to clay), erosion is transport by water, wind, ice, or gravity, and deposition follows when transport energy drops.

Stream and groundwater processes: discharge = cross-sectional area x velocity; gradient = elevation change / horizontal distance; a stream erodes fastest where velocity is highest, and groundwater flows from high hydraulic head to low, recharging where the water table intersects the surface.

Atmospheric structure and circulation: troposphere (weather, temperature decreasing with altitude), stratosphere (ozone, temperature increasing), mesosphere, thermosphere; Coriolis effect deflects winds right in the Northern Hemisphere and left in the Southern, driving global wind belts and gyres.

Relative order of geologic time: Precambrian (Hadean, Archean, Proterozoic) covers about 88% of Earth history, then Paleozoic, Mesozoic, and Cenozoic eras; periods within the Paleozoic are Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian.

Absolute dating: radiometric decay follows N = N0 e^(-lambda t) with half-life t1/2 = ln2 / lambda; after one half-life 50% of parent remains, after two 25%, after three 12.5%.

Datable materials and methods: carbon-14 (half-life about 5730 years) for organic material younger than roughly 50,000 years; potassium-argon, uranium-lead, and rubidium-strontium for older igneous and metamorphic rocks; index fossils must be widespread, abundant, and short-lived.

Fossilization requires rapid burial and hard parts; preservation types include permineralization, molds and casts, carbon films, amber and ice entrapment, and trace fossils such as footprints and burrows.

Major extinction events: end-Ordovician (glaciation), end-Devonian, end-Permian (largest, about 90% of marine species, linked to Siberian Traps volcanism), end-Triassic, and end-Cretaceous (impact at Chicxulub plus Deccan volcanism, ending non-avian dinosaurs).

Key evolutionary milestones: first life about 3.5 billion years ago (prokaryotes), oxygen-producing photosynthesis and banded iron formations, eukaryotes about 1.8 billion years ago, Cambrian explosion about 541 million years ago, land plants and vertebrates, then mammals radiating after the end-Cretaceous extinction.

Uniformitarianism: present-day processes operating over long time spans explain the rock record; catastrophism is reserved for rapid events such as impacts, floods, and eruptions that leave distinctive deposits.

Fossil succession and correlation: distinctive fossil assemblages define biostratigraphic zones, allowing correlation of separated rock layers; the principle of faunal succession states fossil content changes in a consistent order through time.

Kepler's laws: orbits are ellipses with the Sun at one focus; a planet sweeps equal areas in equal times (faster near perihelion); P^2 = a^3 when period is in years and semi-major axis in astronomical units.

Newton's law of gravitation F = G m1 m2 / r^2 explains orbital motion; escape velocity depends on mass and radius, and tidal forces arise because gravitational pull varies with distance across a body.

Earth's seasons result from axial tilt of about 23.5 degrees, not distance from the Sun; solstices mark maximum tilt toward or away from the Sun, equinoxes mark equal day and night, and perihelion occurs in early January.

Moon phases and eclipses: phases follow the Sun-Earth-Moon angle over a 29.5-day synodic month; solar eclipses occur at new moon, lunar eclipses at full moon, and eclipses are rare because the Moon's orbit is inclined about 5 degrees.

Solar system structure: terrestrial planets (Mercury, Venus, Earth, Mars) are small, dense, rocky, and close to the Sun; Jovian planets (Jupiter, Saturn, Uranus, Neptune) are large, low-density, and ringed, with icy moons and dwarf planets beyond Neptune.

Stellar classification and life cycle: spectral sequence OBAFGKM from hottest to coolest; main-sequence stars fuse hydrogen to helium, then become red giants, shed planetary nebulae, and end as white dwarfs if low mass, or supernova and leave neutron stars or black holes if high mass.

Hertzsprung-Russell diagram plots luminosity against temperature; main sequence runs diagonally, giants and supergiants sit upper right, white dwarfs lower left, and mass determines a star's position and lifetime.

Cosmology evidence: Hubble's law v = H0 d shows galaxies receding with distance, cosmic microwave background radiation is the remnant heat of the early universe, and observed light-element abundances support Big Bang nucleosynthesis; the universe is about 13.8 billion years old.

Solar system small bodies and observation: asteroids concentrate in the belt between Mars and Jupiter, comets have ion and dust tails that point away from the Sun, meteor showers come from Earth crossing comet debris trails, and telescopes are classified by aperture and by refracting or reflecting design.

Scientific method sequence: observation, hypothesis, controlled experiment or further observation, analysis, and revision; a hypothesis must be testable and falsifiable, and a theory is a well-tested explanatory framework supported by multiple independent lines of evidence.

Density = mass / volume; Earth's mean density is about 5.5 g/cm3 while surface rock averages about 2.7 g/cm3, which is direct evidence that density increases with depth toward a metallic core.

Isostasy: buoyant lithosphere floats on the asthenosphere; thicker or less dense crust rides higher, so continental crust (about 2.7 g/cm3) stands above oceanic crust (about 3.0 g/cm3).

Rock cycle decision rule: igneous forms from cooling melt, sedimentary from compaction and cementation of weathered debris or precipitates, metamorphic from heat and pressure without melting; any rock type can transform into any other.

Bowen's reaction series predicts mineral crystallization order from mafic magma: olivine and Ca-plagioclase first, then pyroxene and amphibole, then biotite, then K-feldspar, muscovite, and quartz last at lowest temperature.

Silicate tetrahedron (SiO4)4- is the building block of most crustal minerals; isolated tetrahedra give olivine, single chains give pyroxene, double chains amphibole, sheets micas and clays, frameworks quartz and feldspar.

Relative dating principles: superposition (oldest at bottom in undisturbed layers), original horizontality, lateral continuity, cross-cutting relationships (a feature cutting another is younger), and inclusions (a fragment inside a rock is older than the rock).

Unconformity types: angular (tilted layers eroded then buried), disconformity (erosion surface between parallel layers), and nonconformity (sedimentary rock over igneous or metamorphic basement).

Map and graph skills: contour lines close uphill indicate a hill, hachured contours mark depressions, contour spacing indicates slope steepness, and a topographic profile is built by plotting elevation along a transect.

Earth's interior layers by composition: crust (5-70 km), mantle (to about 2900 km), outer core (liquid iron-nickel), inner core (solid iron-nickel); by physical properties: lithosphere, asthenosphere, mesosphere, outer core, inner core.

Seismic evidence: P waves (compressional, fastest, travel through solids and liquids) refract away from the outer core, while S waves (shear, slower) cannot pass through liquid, proving the outer core is liquid; the Moho marks the crust-mantle boundary.

Plate boundary rules: divergent boundaries produce ridges, rift valleys, and shallow quakes; convergent boundaries give subduction, trenches, volcanic arcs, and deep quakes; transform boundaries give strike-slip faults and shallow quakes with no volcanism.

Seafloor spreading evidence: symmetric magnetic striping about ridges, youngest seafloor at ridge crests, age increasing outward, and matching continental margins and fossil belts across ocean basins.

Earthquake magnitude versus intensity: magnitude is a single instrumental measure of energy released (moment magnitude scale), while intensity (Mercalli) describes observed shaking and damage and decreases with distance from the epicenter.

Volcano types linked to magma: shield volcanoes from low-viscosity mafic lava (gentle slopes, Hawaii), stratovolcanoes from viscous andesitic or felsic magma (steep, explosive, Ring of Fire), and cinder cones from short-lived gas-rich eruptions.

Weathering versus erosion: weathering is in-place breakdown (mechanical such as frost wedging, chemical such as hydrolysis of feldspar to clay), erosion is transport by water, wind, ice, or gravity, and deposition follows when transport energy drops.

Stream and groundwater processes: discharge = cross-sectional area x velocity; gradient = elevation change / horizontal distance; a stream erodes fastest where velocity is highest, and groundwater flows from high hydraulic head to low, recharging where the water table intersects the surface.

Atmospheric structure and circulation: troposphere (weather, temperature decreasing with altitude), stratosphere (ozone, temperature increasing), mesosphere, thermosphere; Coriolis effect deflects winds right in the Northern Hemisphere and left in the Southern, driving global wind belts and gyres.

Relative order of geologic time: Precambrian (Hadean, Archean, Proterozoic) covers about 88% of Earth history, then Paleozoic, Mesozoic, and Cenozoic eras; periods within the Paleozoic are Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian.

Absolute dating: radiometric decay follows N = N0 e^(-lambda t) with half-life t1/2 = ln2 / lambda; after one half-life 50% of parent remains, after two 25%, after three 12.5%.

Datable materials and methods: carbon-14 (half-life about 5730 years) for organic material younger than roughly 50,000 years; potassium-argon, uranium-lead, and rubidium-strontium for older igneous and metamorphic rocks; index fossils must be widespread, abundant, and short-lived.

Fossilization requires rapid burial and hard parts; preservation types include permineralization, molds and casts, carbon films, amber and ice entrapment, and trace fossils such as footprints and burrows.

Major extinction events: end-Ordovician (glaciation), end-Devonian, end-Permian (largest, about 90% of marine species, linked to Siberian Traps volcanism), end-Triassic, and end-Cretaceous (impact at Chicxulub plus Deccan volcanism, ending non-avian dinosaurs).

Key evolutionary milestones: first life about 3.5 billion years ago (prokaryotes), oxygen-producing photosynthesis and banded iron formations, eukaryotes about 1.8 billion years ago, Cambrian explosion about 541 million years ago, land plants and vertebrates, then mammals radiating after the end-Cretaceous extinction.

Uniformitarianism: present-day processes operating over long time spans explain the rock record; catastrophism is reserved for rapid events such as impacts, floods, and eruptions that leave distinctive deposits.

Fossil succession and correlation: distinctive fossil assemblages define biostratigraphic zones, allowing correlation of separated rock layers; the principle of faunal succession states fossil content changes in a consistent order through time.

Kepler's laws: orbits are ellipses with the Sun at one focus; a planet sweeps equal areas in equal times (faster near perihelion); P^2 = a^3 when period is in years and semi-major axis in astronomical units.

Newton's law of gravitation F = G m1 m2 / r^2 explains orbital motion; escape velocity depends on mass and radius, and tidal forces arise because gravitational pull varies with distance across a body.

Earth's seasons result from axial tilt of about 23.5 degrees, not distance from the Sun; solstices mark maximum tilt toward or away from the Sun, equinoxes mark equal day and night, and perihelion occurs in early January.

Moon phases and eclipses: phases follow the Sun-Earth-Moon angle over a 29.5-day synodic month; solar eclipses occur at new moon, lunar eclipses at full moon, and eclipses are rare because the Moon's orbit is inclined about 5 degrees.

Solar system structure: terrestrial planets (Mercury, Venus, Earth, Mars) are small, dense, rocky, and close to the Sun; Jovian planets (Jupiter, Saturn, Uranus, Neptune) are large, low-density, and ringed, with icy moons and dwarf planets beyond Neptune.

Stellar classification and life cycle: spectral sequence OBAFGKM from hottest to coolest; main-sequence stars fuse hydrogen to helium, then become red giants, shed planetary nebulae, and end as white dwarfs if low mass, or supernova and leave neutron stars or black holes if high mass.

Hertzsprung-Russell diagram plots luminosity against temperature; main sequence runs diagonally, giants and supergiants sit upper right, white dwarfs lower left, and mass determines a star's position and lifetime.

Cosmology evidence: Hubble's law v = H0 d shows galaxies receding with distance, cosmic microwave background radiation is the remnant heat of the early universe, and observed light-element abundances support Big Bang nucleosynthesis; the universe is about 13.8 billion years old.

Solar system small bodies and observation: asteroids concentrate in the belt between Mars and Jupiter, comets have ion and dust tails that point away from the Sun, meteor showers come from Earth crossing comet debris trails, and telescopes are classified by aperture and by refracting or reflecting design.