Here you’ll find 75 Earth science words that start with P that begin with P, organized from “P-wave” to “Pyroxene”. They include common terms used in classes, fieldwork, climate studies, and geologic mapping.
Earth science words that start with P are a curated set of terminology covering processes, materials, measurements, and landforms. For example, the “P-wave” helped seismologists map Earth’s interior, while “pyroxene” is one of the most common rock-forming minerals.
Below you’ll find the table with Term, Definition, Category, Example, and Source.
Term: The listed word or phrase; you can scan it to find a specific concept quickly.
Definition: A concise one- or two-sentence explanation you can read to grasp each term’s basic meaning and use.
Category: The topic group such as “Process”, “Mineral”, or “Landform” to help you filter related entries.
Example: A short real-world instance or application that shows how the term appears in Earth science work.
Source: A pointer to further reading or an authoritative glossary so you can follow up for more detail.
Earth science words that start with P
| Term | Discipline | Typical units/scale | Related concepts |
|---|---|---|---|
| P-wave | Seismology | m/s, km/s, seconds | S-wave, seismic wave |
| Paleoclimate | Climatology, Paleoclimatology | years, ka, °C | Proxy, ice core |
| Paleontology | Geology | fossil ages (years), stratigraphic scale | Fossils, stratigraphy |
| Paleomagnetism | Geology | microtesla, degrees | Magnetic reversals, plate tectonics |
| Paleosol | Soil science, Geology | m, stratigraphic depth | Soil horizon, pedogenesis |
| Paleoceanography | Oceanography | years, ppm, °C | Paleoclimate, proxies |
| Paleogeography | Geology | geographic scale, Ma | Plate tectonics, paleomap |
| Permafrost | Geology, Cryosphere | °C, meters, years | Active layer, thaw |
| Periglacial | Geomorphology | meters to km, °C | Permafrost, frost heave |
| Permeability | Hydrogeology, Petrology | darcy, m², m/s | Porosity, hydraulic conductivity |
| Porosity | Hydrogeology, Petrology | %, fraction | Permeability, pore space |
| Primary porosity | Petrology, Sedimentology | % | Diagenesis, secondary porosity |
| Pedology | Soil science | horizon depth (cm), % | Pedogenesis, soil classification |
| Pedogenesis | Soil science | years, cm | Pedology, soil horizon |
| Parent material | Soil science | rock type, m | Pedogenesis, soil texture |
| Podzol (Podzolic soil) | Soil science | horizon depth (cm) | Spodosol, leaching |
| Peat | Soil science, Ecology | %, cm, carbon (t/ha) | Organic soil, bog |
| Pluton | Igneous petrology | km, Ma | Intrusion, batholith |
| Plutonic | Petrology | grain size mm | Pluton, intrusive rock |
| Plagioclase | Mineralogy, Petrology | % composition, hardness | Feldspar, mineralogy |
| Pyroxene | Mineralogy | hardness, composition | Olivine, mafic minerals |
| Pyrite | Mineralogy, Economic geology | g/cm³, %S | Sulfide, acid rock drainage |
| Pumice | Volcanology | kg/m³, porosity % | Scoria, vesicular rock |
| Pillow lava | Volcanology | m, cooling rate | Basalt, submarine eruption |
| Pahoehoe | Volcanology | m, viscosity | Aa lava, basalt |
| Pyroclast | Volcanology | mm–m | Tephra, ash |
| Pyroclastic flow | Volcanology | km/h, m | Nuée ardente, ash flow |
| Pyroclastic surge | Volcanology | m, m/s | Pyroclastic flow, density current |
| Plinian eruption | Volcanology | VEI, km height | Explosive eruption, tephra |
| Phreatic eruption | Volcanology, Hydrogeology | steam pressure, meters | Phreatomagmatic, steam explosion |
| Phreatomagmatic | Volcanology | meters, VEI | Phreatic, magma-water interaction |
| Phreatic zone | Hydrogeology | m, water table depth | Aquifer, vadose zone |
| Phreatic surface | Hydrogeology | m, water table depth | Water table, phreatic zone |
| Photic zone | Oceanography | m (0–200 m) | Euphotic zone, photosynthesis |
| Phytoplankton | Oceanography | cells/mL, biomass | Plankton, primary production |
| Plankton | Oceanography | cells/L, biomass | Phytoplankton, zooplankton |
| Pelagic | Oceanography, Sedimentology | water column depth, km² | Benthic, open ocean |
| Pelagic sediment | Oceanography | cm/ky, grain size | Biogenic ooze, abyssal clay |
| Placer | Economic geology | grams, tons | Alluvial deposit, gold |
| Plain | Geomorphology | km², m elevation | Plateau, valley |
| Plateau | Geomorphology | m elevation, km² | Plain, uplift |
| Piedmont | Geomorphology | km, slope % | Alluvial fan, foothills |
| Piedmont glacier | Glaciology | km, m/year | Valley glacier, ice sheet |
| Point bar | Fluvial geomorphology | m, m³/s | Meander, cut bank |
| Progradation | Sedimentology | m/yr, km | Delta growth, aggradation |
| Playa | Geomorphology, Arid lands | km², cm depth | Salt flat, ephemeral lake |
| Pluvial | Climatology, Geomorphology | mm/year, ka | Pluvial lake, wetter climates |
| Pan evaporation | Hydrology | mm/day, mm/year | Evaporation, evapotranspiration |
| Particulate matter | Atmospheric science | µg/m³, PM2.5 | Aerosol, air pollution |
| Pressure (atmospheric) | Meteorology | Pascals, hPa, millibars | Temperature, altitude |
| Pressure head | Hydrology | m (water column) | Hydraulic head, piezometric |
| Potential evapotranspiration | Hydrology, Meteorology | mm/day, mm/year | Evaporation, transpiration |
| Proxy (climate proxy) | Paleoclimatology | years, °C proxies | Ice core, tree ring |
| Pycnocline | Oceanography | m depth, kg/m³ | Thermocline, halocline |
| Pore pressure | Geotechnical, Hydrogeology | Pascals, kPa | Effective stress, consolidation |
| Porphyritic | Petrology | grain size mm | Phenocryst, groundmass |
| Porphyry | Economic geology, Petrology | m³, % ore | Porphyritic, hydrothermal |
| Pegmatite | Petrology, Mineralogy | cm–m crystals | Granite, mineralogy |
| Peridotite | Petrology | km, % olivine | Mantle, ultramafic |
| Placer deposit | Economic geology | grams, tons | Alluvial, heavy-mineral concentration |
| Plankton | Oceanography | cells/mL, biomass | Phytoplankton, zooplankton |
| Polar vortex | Meteorology | km, hPa | Jet stream, stratosphere |
| Polar ice cap | Glaciology | km², m thickness | Ice sheet, sea ice |
| Precipitation | Meteorology | mm, inches, mm/hr | Rain, snowfall |
| Precession | Astronomy, Paleoclimatology | arcseconds/year, kyr | Milankovitch cycles, obliquity |
| Proterozoic | Geology | Ma (2,500–541 Ma) | Precambrian, Archean |
| Plate tectonics | Geology | cm/yr (motion), Ma | Continental drift, seafloor spreading |
| Plate boundary | Geology | km, degrees, cm/yr | Transform, convergent |
| Passive margin | Geology, Oceanography | km, km shelf | Continental shelf, rifted margin |
| Petroleum | Economic geology | barrels, m³, API° | Hydrocarbon, reservoir |
| Piezometer | Hydrogeology, Geotechnical | m, kPa | Pore pressure, monitoring well |
| Pedocal | Soil science | horizon depth (cm) | Arid soils, calcic horizon |
| Phyllite | Metamorphic petrology | grain size mm | Schist, slate |
| Plunge (structural geology) | Structural geology | degrees, m | Fold axis, plunge line |
| Porosity-permeability relationship | Hydrogeology, Petrology | % and m² | Porosity, permeability |
Descriptions
P-wave
Primary (compressional) seismic wave that travels fastest through Earth; used to locate earthquakes and probe interior structure. https://www.usgs.gov/programs/earthquake-hazards/learn
Paleoclimate
Study of past climates using proxies like tree rings, sediments, and ice cores to understand Earth’s long-term climate change. https://www.ipcc.ch
Paleontology
Science of ancient life through fossils; informs evolution, past environments, and stratigraphic correlations. https://www.usgs.gov/faqs/what-paleontology
Paleomagnetism
Study of Earth’s past magnetic field recorded in rocks, used to reconstruct plate motions and magnetic reversals. https://earthobservatory.nasa.gov/features/Paleomagnetism
Paleosol
Ancient soil preserved in the rock record that records past climate and surface conditions. https://geology.com/articles/paleosols/
Paleoceanography
Study of past ocean conditions (temperature, chemistry, circulation) using sediments, isotopes, and fossils. https://www.ncdc.noaa.gov/paleo/paleoceanography
Paleogeography
Reconstruction of past continental positions and landscapes to understand Earth’s historical geography. https://www.sciencedirect.com/topics/earth-and-planetary-sciences/paleogeography
Permafrost
Ground that remains at or below 0 °C for at least two consecutive years; governs cold-region hydrology and carbon storage. https://www.usgs.gov/centers/ice-and-permafrost-research
Periglacial
Processes and landforms formed by freeze–thaw in cold, non-glacial environments (e.g., patterned ground). https://pubs.usgs.gov/of/2007/1046/
Permeability
Measure of a material’s ability to transmit fluids; controls groundwater and hydrocarbon flow. https://water.usgs.gov/ogw/permeability.html
Porosity
Fraction of rock or soil volume that is open space available for fluids; important for aquifers and reservoirs. https://pubs.usgs.gov/gip/Geology_of_the_National_Parks/porosity.html
Primary porosity
Original pore space formed during rock/sediment deposition (e.g., between grains), later altered by burial and cementation. https://geology.com/articles/porosity-permeability/
Pedology
Scientific study of soil formation, classification, and mapping. https://www.nrcs.usda.gov/wps/portal/nrcs/main/soils/
Pedogenesis
Processes that form soils from parent material via weathering, organic activity, and climate. https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/
Parent material
Original geologic material (bedrock, alluvium) from which a soil develops; influences texture and minerals. https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/
Podzol (Podzolic soil)
Acidic, leached soil with distinct organic and iron/aluminum-enriched horizons, common in cool, humid climates. https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/
Peat
Accumulation of partially decayed plant material in waterlogged conditions; important carbon store and precursor to coal. https://www.britannica.com/science/peat
Pluton
Body of intrusive igneous rock crystallized from magma below the surface; size ranges from small stocks to large batholiths. https://pubs.usgs.gov/gip/Geology_of_the_National_Parks/plutonic_rocks.html
Plutonic
Describing coarse-grained igneous rocks that crystallized slowly underground (e.g., granite). https://geology.com/rocks/
Plagioclase
Common group of feldspar minerals important in igneous and metamorphic rocks; composition ranges from albite to anorthite. https://www.mineralseducationcoalition.org/minerals-database/plagioclase/
Pyroxene
Mineral group common in mafic and ultramafic rocks; influences rock color and melting behavior. https://geology.com/minerals/pyroxene.shtml
Pyrite
Iron sulfide (FeS2) common in sedimentary and metamorphic rocks; can produce acidic drainage when exposed. https://pubs.usgs.gov/gip/Geology_of_the_National_Parks/pyrite.html
Pumice
Light, highly vesicular volcanic rock produced by explosive eruptions; can float on water when abundant. https://www.usgs.gov/observatories/california-volcano-observatory/learn-about-volcanoes
Pillow lava
Rounded, lobate basaltic lava forms when lava erupts underwater, producing pillow-shaped structures. https://volcanoes.usgs.gov/vsc/glossary/pillow_lava.html
Pahoehoe
Smooth, ropy basaltic lava flow texture formed from low-viscosity lava. https://www.usgs.gov/faqs/what-pahoehoe-and-aa
Pyroclast
Fragment of volcanic rock ejected during eruptions; size ranges from ash to large bombs. https://volcanoes.usgs.gov/vsc/glossary/pyroclastic.html
Pyroclastic flow
Fast-moving, hot mixture of gas and volcanic debris that races downslope during explosive eruptions and is highly destructive. https://volcano.si.edu/learn_galleries.cfm
Pyroclastic surge
Less-dense, turbulent component of pyroclastic density currents that can travel farther and overtop barriers. https://pubs.usgs.gov/gip/volc/pyroclastic.html
Plinian eruption
Highly explosive eruption type producing sustained gas-and-ash plumes reaching tens of kilometers into the atmosphere. https://volcanoes.usgs.gov/vsc/glossary/plinian.html
Phreatic eruption
Steam-driven explosive eruption caused by heating of groundwater by magma, producing ash but little new magma. https://www.usgs.gov/volcano-hazards
Phreatomagmatic
Eruption style where magma interacts directly with water, producing fine ash and explosive fragmentation. https://volcanoes.usgs.gov/vsc/glossary/phreatomagmatic.html
Phreatic zone
Saturated subsurface zone where all pore spaces are filled with groundwater; contrasts with the unsaturated zone. https://water.usgs.gov/edu/qa-what-is-water-table.html
Phreatic surface
Synonym for water table; the level in the ground below which soils and rocks are saturated with water. https://water.usgs.gov/edu/qa-what-is-water-table.html
Photic zone
Upper ocean layer where sunlight penetrates enough for photosynthesis; depth varies with clarity. https://oceanservice.noaa.gov/facts/light.html
Phytoplankton
Microscopic marine plants that perform photosynthesis and form the base of aquatic food webs. https://oceanservice.noaa.gov/facts/phytoplankton.html
Plankton
Organisms that drift in the water column; includes plants and animals critical to marine ecosystems. https://oceanservice.noaa.gov/facts/plankton.html
Pelagic
Related to the open water column away from the shore or seafloor; pelagic organisms live in the water column. https://oceanservice.noaa.gov/facts/pelagic.html
Pelagic sediment
Sediment deposited in the deep ocean, often from settling plankton remains or fine clays. https://oceanservice.noaa.gov/facts/sediment.html
Placer
Concentration of heavy minerals (e.g., gold, tin) in stream or beach sediments formed by gravity separation. https://www.usgs.gov/centers/earth-resources-observatory-and-analytics
Plain
Broad, relatively flat region of low relief formed by deposition or erosion. https://www.britannica.com/science/plain
Plateau
Elevated flat or gently rolling area often formed by uplift or lava flows. https://www.britannica.com/science/plateau
Piedmont
Gently sloping area at the base of mountains formed by coalescing fans or erosion. https://geomaps.wr.usgs.gov/parks/
Piedmont glacier
Glacier that spreads out as it reaches a lowland, forming a broad lobe at mountain fronts. https://www.usgs.gov/special-topics/ice-and-snow-science
Point bar
Depositional feature on the inside bend of a river meander where sediment accumulates. https://water.usgs.gov/edu/geomorph.html
Progradation
Seaward growth of a shoreline or delta due to sediment accumulation exceeding sea-level rise. https://pubs.er.usgs.gov
Playa
Seasonal or ephemeral ephemeral lake basin in arid regions that dries to leave salt or mud flats. https://www.britannica.com/science/playa
Pluvial
Term describing wetter-than-present climate intervals or lakes formed under those conditions. https://www.britannica.com/science/pluvial
Pan evaporation
Measure of water evaporation from a standardized pan used to estimate evaporative demand. https://www.usgs.gov/mission-areas/water-resources
Particulate matter
Airborne solid or liquid particles that impact air quality and human health; measured as PM10, PM2.5. https://www.epa.gov/pm-pollution
Pressure (atmospheric)
Force per unit area exerted by the atmosphere; important for weather, also varies with altitude. https://www.ncdc.noaa.gov/news/what-air-pressure
Pressure head
Component of hydraulic head representing pressure expressed as height of water column in porous media. https://water.usgs.gov/ogw/hydrogeology-hydraulics.html
Potential evapotranspiration
Amount of evaporation and transpiration that would occur if water were unlimited; used in water-balance models. https://www.fao.org/3/x0490e/x0490e07.htm
Proxy (climate proxy)
Natural recorder (e.g., tree rings, ice cores) used to infer past climate variables like temperature or precipitation. https://www.ncdc.noaa.gov/data-access/paleoclimatology-data
Pycnocline
Layer in the ocean with a rapid change in water density with depth, often controlling mixing. https://oceanservice.noaa.gov/facts/pycnocline.html
Pore pressure
Pressure of fluids within pore spaces of soils or rocks affecting stability and fluid flow. https://water.usgs.gov/ogw/porepressure/
Porphyritic
Texture of igneous rocks where large crystals (phenocrysts) are embedded in a finer-grained matrix. https://geology.com/rocks/igneous-rocks.shtml
Porphyry
Type of igneous rock and related ore deposits formed by hydrothermal processes, important for copper and gold. https://pubs.usgs.gov/of/2000/of00-013/
Pegmatite
Coarse-grained igneous rock with very large crystals formed during late-stage crystallization; source of rare minerals. https://www.mineralseducationcoalition.org/minerals-database/pegmatite/
Peridotite
Dense, coarse-grained ultramafic rock dominated by olivine; major constituent of Earth’s mantle. https://www.britannica.com/science/peridotite
Placer deposit
Accumulation of valuable minerals in stream or beach sediments by mechanical sorting. https://pubs.usgs.gov/gip/Placer/
Plankton
Collection of drifting organisms in water that form essential parts of aquatic food webs. https://oceanservice.noaa.gov/facts/plankton.html
Polar vortex
Large-scale circulating low-pressure zone near a pole that influences cold air outbreaks and winter weather. https://www.noaa.gov/education/resource-collections/weather-atmosphere/polar-vortex
Polar ice cap
High-latitude ice-covered region (Greenland, Antarctica, or seasonal caps) influencing sea level and climate. https://nsidc.org/cryosphere/seaice/
Precipitation
All forms of water falling from the atmosphere to Earth’s surface, central to the hydrologic cycle. https://www.noaa.gov/education/resource-collections/weather-atmosphere/what-is-precipitation
Precession
Slow wobble of Earth’s rotation axis (~26,000-year cycle) affecting long-term climate patterns. https://earthobservatory.nasa.gov/features/OrbitalEccentricity
Proterozoic
Geologic eon from 2.5 billion to 541 million years ago marked by atmospheric and biological changes. https://www.britannica.com/science/Proterozoic-Eon
Plate tectonics
Theory describing movement of lithospheric plates that shapes continents, earthquakes, and mountain building. https://www.usgs.gov/programs/volcano-hazards/what-plate-tectonics
Plate boundary
Zones where tectonic plates interact (convergent, divergent, transform), producing earthquakes, volcanism, and deformation. https://pubs.usgs.gov/gip/tectonics/
Passive margin
Continental edge away from active plate boundaries, characterized by wide shelves and sediment accumulation. https://geology.com/records/passive-margin.shtml
Petroleum
Naturally occurring hydrocarbons (oil and gas) formed from ancient organic matter and trapped in reservoirs. https://www.usgs.gov/energy-and-minerals/petroleum
Piezometer
Instrument or well used to measure groundwater pressure or hydraulic head in soils and rocks. https://water.usgs.gov/ogw/piezometers.html
Pedocal
Soil type found in arid regions with calcium carbonate accumulation (caliche) in lower horizons. https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/
Phyllite
Fine-grained metamorphic rock between slate and schist with a silky sheen from aligned minerals. https://geology.com/rocks/phyllite.shtml
Plunge (structural geology)
Angle a fold or lineation makes with the horizontal, measuring the tilt of structures in rocks. https://pubs.usgs.gov/pp/pp1252/
Porosity-permeability relationship
Describes how pore space and connectivity control fluid flow; high porosity doesn’t always mean high permeability. https://water.usgs.gov/ogw/permeability.html