earth science final

Catastrophism

Idea that Earth's features formed mainly from sudden, short, violent events (e.g., floods, earthquakes).

Uniformitarianism

Principle that Earth's processes operating today also operated in the past ("the present is the key to the past").

The Birth of Modern Geology

Shift in the 1700s-1800s toward uniformitarianism and scientific study of Earth's processes (e.g., Hutton, Lyell).

Geology Today

Integrates uniformitarianism, catastrophism, and modern tools (radiometric dating, satellites, plate tectonics).

Numerical dating

Assigning an actual age in years to rocks/events.

Relative dating

Determining the order of events without exact ages.

Principle of Superposition

In undisturbed layers, oldest rocks are at the bottom, youngest at the top.

Original Horizontality

Sedimentary layers are originally deposited flat.

Lateral Continuity

Layers extend outward until they thin or encounter a barrier.

Cross-Cutting Relationships

A geologic feature that cuts another is younger than what it cuts.

Principle of Inclusions

Rock fragments inside another rock are older than the host rock.

Unconformity

A gap in the geologic record caused by erosion or non-deposition.

Angular unconformity

Tilted older layers overlain by flat younger layers

Disconformity

Gap between parallel sedimentary layers

Nonconformity

Sedimentary rock over igneous/metamorphic rock

Grand Canyon unconformities

Multiple visible rock record gaps in canyon walls

Fossil

Preserved remains or traces of past life.

Permineralization

Minerals fill pores of organic material.

Molds and casts

Mold = hollow impression; cast = filled mold.

Carbonization/Impressions

Thin carbon film or imprint left in rock.

Amber fossils

Organisms trapped and preserved in tree resin.

Trace fossils

Evidence of activity (footprints, burrows).

Conditions favoring fossilization

Rapid burial, low oxygen, hard parts, little disturbance.

Correlation

Matching rock layers of similar age in different locations.

Principle of fossil succession

Fossil species appear and disappear in a predictable order.

Index fossils

Widespread, short-lived fossils used to date rock layers.

Fossil assemblages

Groups of fossils that identify a specific time period.

Environmental indicators

Fossils that reveal past environments (marine, desert, etc.).

8.5 Radiometric Dating

Radiometric dating

Dating rocks using radioactive decay rates.

Atomic structure

Protons and neutrons in nucleus; electrons outside.

Radioactive decay

Unstable isotopes break down into stable ones.

Half-life

Time required for half of radioactive atoms to decay.

Unstable isotopes

Radioactive elements used for dating Earth materials.

Earth's oldest rocks

Dated using long half-life isotopes (e.g., uranium).

Carbon-14 dating

Used for recent organic remains (up to ~50,000 years).

Numerical dating of sedimentary rocks

Done indirectly by dating igneous layers above/below or using index fossils.

Geologic time scale

System organizing Earth's history into eons, eras, periods, epochs.

Precambrian time

Earliest and longest span of Earth history before complex life.

Dynamic tool

Updated as new data and dating methods improve interpretations.

Weather

Short-term atmospheric conditions.

Climate

Long-term average weather patterns.

Nonvariable gases

Constant gases (nitrogen, oxygen).

Variable gases

Change in amount (water vapor, CO₂, ozone).

Troposphere

Lowest layer; weather occurs here.

Stratosphere

Contains ozone layer; temperature increases with height.

Mesosphere

Cold middle layer; meteors burn here.

Thermosphere

Upper layer; very high temperatures, auroras.

Air pressure

Decreases with altitude.

Temperature structure

Changes define atmospheric layers.

Earth's rotation

Causes day and night.

Earth's orbit

Causes seasonal changes.

Sun angle

Controls heating intensity.

Solstices

Longest and shortest days of year.

Equinoxes

Day and night are equal in length.

11.5 Energy, Heat, Temperature

Kinetic energy

Energy of motion.

Potential energy

Stored energy.

Heat

Energy transfer due to temperature difference.

Temperature

Measure of average kinetic energy of particles.

Conduction

Direct transfer through contact.

Convection

Heat transfer by fluid movement.

Radiation

Energy transfer through electromagnetic waves.

Solar radiation

Energy from the Sun.

Laws of radiation

Govern emission, absorption, and wavelength behavior.

Albedo

Reflectivity of Earth's surface.

Reflection

Bouncing of solar energy.

Scattering

Diffusion of light in many directions.

Absorption

Energy taken in by surface or atmosphere.

Greenhouse effect

Atmosphere traps heat and warms Earth.

Rising CO₂

Increase due to human activity.

Atmospheric response

Warming and climate shifts.

Consequences

Sea level rise, weather extremes, ecosystem changes.

Isotherms

Lines of equal temperature on maps.

Temperature data

Numerical measurements used to analyze climate patterns.

Land vs water heating

Land heats/cools faster than water.

Altitude

Temperature decreases with height.

Geographic position

Latitude and winds affect temperature.

Albedo variations

Lighter surfaces reflect more heat.

World temperature distribution

Patterns driven by latitude, seasons, land/ocean distribution, and winds.