Geology and Hydrology Vocabulary Review

A collection of vocabulary flashcards to help study key terms and concepts related to hydrology, mass wasting, volcanoes, and earthquakes.

Hydrologic Cycle

Continuous movement of water through evaporation, condensation, precipitation, and runoff.

Channel

Main path where river water flows.

Floodplain

Flat land next to a river that floods.

Watershed

Area draining into a single river system.

Divide

Boundary separating drainage basins.

Discharge (Q = W×D×V)

Stream flow rate calculated by width, depth, and velocity.

Base Level

Lowest level a river can erode to.

Base Flow

Normal groundwater-fed river flow.

Flood Flow

Sudden discharge increase after rainfall.

Hydrograph

Graph showing stream discharge over time.

Alluvium

Sediment deposited by running water.

Meander

Curving bend in a river channel.

Delta

Landform at a river mouth formed by deposition.

Natural Levee

Raised banks built by repeated floods.

Recurrence Interval

Average time between floods of similar size.

Mass Wasting

Downslope movement of material by gravity.

Erosion

Removal and transport of surface material.

Slope Stability

Balance between driving and resisting forces.

Shear Resistance

Friction that prevents downslope movement.

Water Saturation

Adds weight, reduces friction, promotes failure.

Oversteepening

Slope angle exceeds stability limit.

Earthquake Trigger

Shaking that causes slope failure.

Vegetation Removal

Reduces root stability on slopes.

Creep

Very slow, gradual downslope movement.

Slump

Curved, rotational movement of soil/rock.

Rockfall

Rapid fall of rock from steep slopes.

Debris Flow

Flow of mud and debris mixed with water.

Avalanche

Fast snow or ice flow down a slope.

Rock Structure

Bedding/joints affect likelihood of failure.

Mitigation

Slope stabilization via drainage, walls, vegetation.

Magma

Molten rock beneath Earth’s surface.

Lava

Magma that erupts onto the surface.

Viscosity

Resistance to flow; controls eruption style.

Gas Content

Dissolved gases controlling explosivity.

Shield Volcano

Broad, gentle, basaltic volcano.

Stratovolcano

Steep, explosive volcano with alternating lava and ash.

Cinder Cone

Small, steep cone made of ash and rock fragments.

Caldera

Large collapse depression after eruption.

Pyroclastic Flow

Fast, hot avalanche of gas and ash.

Lahar

Mudflow made of volcanic debris and water.

Ash Fall

Widespread fine volcanic material from eruption.

VEI

Scale that measures eruption size and explosivity.

Hot Spot

Volcano formed over a stationary mantle plume.

Gas Monitoring

Measuring SO₂/CO₂ to predict eruptions.

Volcanic Hazards

Lava, ash, gases, climate or health effects.

Elastic Rebound Theory

Rocks deform then snap, releasing energy.

Stress

Force applied to rock.

Strain

Rock deformation caused by stress.

P-Wave

Fast, compressional seismic wave.

S-Wave

Slower, shear wave that doesn’t travel through liquid.

Surface Wave

Slowest seismic wave that causes the most damage.

Seismograph

Instrument recording seismic waves.

Richter Scale

Measures earthquake magnitude (energy released).

Mercalli Scale

Measures earthquake intensity (damage observed).

Epicenter

Point on surface above earthquake focus.

Aftershock

Smaller quake following main event.

Normal Fault

Hanging wall moves down due to tension.

Reverse Fault

Hanging wall moves up due to compression.

Strike-Slip Fault

Horizontal side-to-side motion.

Liquefaction

Wet ground loses strength, behaving like liquid.