Environmental Geology Final

Soil

A natural body composed of mineral particles, organic matter, water, and air that forms at Earth’s surface and supports plant life.

Soil horizon

A distinct layer within soil (e.g., O, A, E, B, C horizons) formed by processes like leaching, organic accumulation, and weathering.

Hydrolysis (chemical weathering of feldspars)

A reaction where minerals (especially feldspars) react with acidic water, breaking down into clay minerals and dissolved ions.

Carbonation (chemical weathering of carbonates)

Reaction of carbon dioxide dissolved in water (carbonic acid) with carbonate minerals (like limestone), leading to dissolution.

Erosion

The physical removal and transport of weathered material by wind, water, ice, or gravity.

Humus

Dark, organic material in soil formed from decomposed plant and animal matter; important for nutrient retention.

Kaolinite

A common clay mineral formed by the chemical weathering of feldspar, especially in warm, wet climates.

Hydrologic cycle

The continuous movement of water through evaporation, condensation, precipitation, infiltration, and runoff.

Evapotranspiration

Combined water loss from evaporation (surface) and transpiration (plants).

Runoff

Water that flows over land into streams and rivers after precipitation.

Infiltration

Water soaking into the ground from the surface.

Precipitation

Water falling from the atmosphere (rain, snow, sleet, hail).

Stream morphology terms

Physical characteristics of streams, including: Channel, Meander, Floodplain, Gradient, Discharge

Groundwater

Water stored beneath Earth’s surface in soil and rock pores.

General chemistry of groundwater

Typically contains dissolved ions (Ca²⁺, Mg²⁺, Na⁺, HCO₃⁻) from rock-water interactions

Karst topography

Landscape formed by dissolution of limestone, featuring caves, sinkholes, and underground drainage.

Sinkholes

Depressions formed when surface ground collapses or dissolves into voids in karst systems.

Water hardness

Measure of dissolved calcium and magnesium ions.

Total dissolved solids (TDS)

Total concentration of dissolved substances in water.

Unconfined aquifer

Directly recharged from surface; upper boundary is the water table.

Confined aquifer

Bounded by impermeable layers; water is under pressure.

Aquitards

Low-permeability layers that restrict groundwater flow.

Potentiometric surface

The level to which water will rise in a confined aquifer.

Water table

The upper surface of groundwater in an unconfined aquifer.

Troposphere

Lowest layer; weather occurs here; temperature decreases with height.

Stratosphere

Above troposphere; contains ozone layer; temperature increases with height.

Top three atmospheric gases

Nitrogen (~78%), Oxygen (~21%), Argon (~0.93%).

Insolation

Incoming solar radiation received by Earth.

Albedo

Reflectivity of a surface (higher = more reflection).

Infrared radiation

Heat energy emitted by Earth.

Greenhouse effect

Warming caused by gases trapping infrared radiation

Greenhouse gases

CO₂, CH₄, H₂O vapor, N₂O.

Adiabatic cooling

Cooling of rising air due to expansion without heat exchange.

Latent heat energy

Heat absorbed or released during phase changes of water.

Convection

Vertical movement of air due to temperature differences.

Ozone (O₃)

Gas that absorbs harmful UV radiation in the stratosphere.

Aerosols

Tiny particles in the atmosphere that affect climate and radiation balance.

General seawater chemistry

Dominated by Na⁺ and Cl⁻ ions; salinity ~35‰.

Continental Shelf

shallow submerged edge of continent

Continental Slope

steep drop

Continental Rise

sediment accumulation at base

ENSO (El Niño/La Niña)

Climate oscillation affecting ocean temperatures and global weather patterns.

Barrier islands

Long, narrow offshore sand deposits protecting coastlines.

Longshore current

Current moving parallel to shore.

Drift

Sediment transport along coast by waves.

Hard stabilization

structures (seawalls)

Soft stabilization

beach nourishment

Jetties

stabilize inlets

Groins

trap sand

Seawalls

protect shoreline

Methanogens

Microbes that produce methane in anaerobic environments.

Cyanobacteria

Photosynthetic bacteria that produce oxygen.

Plate tectonics & climate

Controls CO₂ levels via volcanism and weathering.

Milankovitch cycles

Variations in Earth’s orbit affecting climate (eccentricity, tilt, precession).

Biological processes & greenhouse gases

Produce: respiration, methanogenesis
Reduce: photosynthesis

Climate proxy

Indirect evidence of past climate (ice cores, tree rings).

Ruddiman hypothesis

Early agriculture prolonged the current interglacial by increasing greenhouse gases.

Earth’s average albedo

~30%

Glacial vs interglacial periods

Cold vs warm climate phases.

Stadials/interstadials

Short-term colder and warmer periods within glacial times.

Oxygen isotopes & marine isotope stages

Ratios of O¹⁶/O¹⁸ used to infer past temperatures.