SOE Exam 1 Questions and Answers Latest Update 2025/2026
Ga (giga-annum) - Answers billion years ago; standard geology time unit (1 Ga = 1,000 Ma =
1,000,000 Ka = 1,000,000,000 years).
Ma (mega-annum) - Answers million years ago; standard geology time unit.
Ka (kilo-annum) - Answers thousand years ago; standard geology time unit.
Lithosphere - Answers rigid outer shell of Earth made of crust plus uppermost mantle; moves as
tectonic plates.
Asthenosphere - Answers weak, hot, slowly flowing mantle layer beneath the lithosphere that
allows plate motion.
Subduction - Answers when one tectonic plate dives beneath another into the mantle at a trench.
Trench - Answers long, narrow, very deep seafloor depression formed at a subduction zone.
Volcanic arc - Answers chain of volcanoes above a subducting slab (oceanic or continental arc).
Benioff zone - Answers inclined plane of earthquakes that traces a subducting slab into the
mantle.
Stress - Answers force per area acting on rock (compression, tension, shear).
Strain - Answers the deformation that results from stress (change in shape or volume).
Compression - Answers stress that squeezes rock together.
Tension - Answers stress that pulls rock apart.
Shear - Answers stress that slides rock blocks past each other.
Ductile deformation - Answers bending or flowing of rock without breaking, usually at depth and
high temperature.
Brittle deformation - Answers breaking or faulting of rock, usually at shallow, cooler conditions.
cm/yr - Answers centimeters per year; common unit for plate speed measured by GPS.
Geology - Answers scientific study of Earth (materials, processes, history).
Historical geology - Answers reconstructs Earth's past events and processes, asking how and
why they occurred.
Deep time - Answers concept that Earth's history spans billions of years, far beyond human
timescales.
, Scientific method - Answers in geology: observe, hypothesize, predict, test repeatedly, build a
theory.
Hypothesis - Answers tentative explanation that can be tested.
Theory - Answers robust, well-supported explanation built from many tests and lines of evidence.
Big Bang Theory - Answers universe began hot and dense and has been expanding; evidence
includes cosmic microwave background and galactic redshift.
Solar Nebula Theory - Answers solar system formed from a rotating cloud of gas and dust;
explains planet orbits and composition gradients.
Plate Tectonics - Answers lithospheric plates move on the asthenosphere, explaining
earthquakes, volcanoes, mountains, ocean basins.
Evolution (biological) - Answers life changes over time via natural selection acting on variation;
supported by fossils and genetics.
Earth's subsystems - Answers Atmosphere, Hydrosphere, Biosphere, Lithosphere; they interact
and exchange energy and matter.
External energy source - Answers the Sun; drives climate, weather, and the hydrologic cycle.
Internal energy sources - Answers radioactive decay and core heat; drive mantle convection,
volcanism, and plate tectonics.
Mineral - Answers naturally occurring, inorganic, crystalline solid with a specific chemical
composition (example: quartz, SiO₂).
Rock - Answers aggregate of minerals and other materials (example: granite = quartz + feldspar
+ mica).
Fossil - Answers preserved remains or traces of past life (example: trilobite shell, dinosaur
footprint).
Atom - Answers basic unit of matter; protons, neutrons, electrons.
Isotope - Answers atoms of the same element with different numbers of neutrons; useful for
dating and tracing.
Ionic bond - Answers electron transfer between atoms (example: halite, NaCl).
Covalent bond - Answers electron sharing between atoms (example: diamond).
Metallic bond - Answers electrons shared in a "sea," allowing conductivity (example: copper).
Silicates - Answers mineral group built around SiO₄ tetrahedra; dominate Earth's crust (quartz,
Ga (giga-annum) - Answers billion years ago; standard geology time unit (1 Ga = 1,000 Ma =
1,000,000 Ka = 1,000,000,000 years).
Ma (mega-annum) - Answers million years ago; standard geology time unit.
Ka (kilo-annum) - Answers thousand years ago; standard geology time unit.
Lithosphere - Answers rigid outer shell of Earth made of crust plus uppermost mantle; moves as
tectonic plates.
Asthenosphere - Answers weak, hot, slowly flowing mantle layer beneath the lithosphere that
allows plate motion.
Subduction - Answers when one tectonic plate dives beneath another into the mantle at a trench.
Trench - Answers long, narrow, very deep seafloor depression formed at a subduction zone.
Volcanic arc - Answers chain of volcanoes above a subducting slab (oceanic or continental arc).
Benioff zone - Answers inclined plane of earthquakes that traces a subducting slab into the
mantle.
Stress - Answers force per area acting on rock (compression, tension, shear).
Strain - Answers the deformation that results from stress (change in shape or volume).
Compression - Answers stress that squeezes rock together.
Tension - Answers stress that pulls rock apart.
Shear - Answers stress that slides rock blocks past each other.
Ductile deformation - Answers bending or flowing of rock without breaking, usually at depth and
high temperature.
Brittle deformation - Answers breaking or faulting of rock, usually at shallow, cooler conditions.
cm/yr - Answers centimeters per year; common unit for plate speed measured by GPS.
Geology - Answers scientific study of Earth (materials, processes, history).
Historical geology - Answers reconstructs Earth's past events and processes, asking how and
why they occurred.
Deep time - Answers concept that Earth's history spans billions of years, far beyond human
timescales.
, Scientific method - Answers in geology: observe, hypothesize, predict, test repeatedly, build a
theory.
Hypothesis - Answers tentative explanation that can be tested.
Theory - Answers robust, well-supported explanation built from many tests and lines of evidence.
Big Bang Theory - Answers universe began hot and dense and has been expanding; evidence
includes cosmic microwave background and galactic redshift.
Solar Nebula Theory - Answers solar system formed from a rotating cloud of gas and dust;
explains planet orbits and composition gradients.
Plate Tectonics - Answers lithospheric plates move on the asthenosphere, explaining
earthquakes, volcanoes, mountains, ocean basins.
Evolution (biological) - Answers life changes over time via natural selection acting on variation;
supported by fossils and genetics.
Earth's subsystems - Answers Atmosphere, Hydrosphere, Biosphere, Lithosphere; they interact
and exchange energy and matter.
External energy source - Answers the Sun; drives climate, weather, and the hydrologic cycle.
Internal energy sources - Answers radioactive decay and core heat; drive mantle convection,
volcanism, and plate tectonics.
Mineral - Answers naturally occurring, inorganic, crystalline solid with a specific chemical
composition (example: quartz, SiO₂).
Rock - Answers aggregate of minerals and other materials (example: granite = quartz + feldspar
+ mica).
Fossil - Answers preserved remains or traces of past life (example: trilobite shell, dinosaur
footprint).
Atom - Answers basic unit of matter; protons, neutrons, electrons.
Isotope - Answers atoms of the same element with different numbers of neutrons; useful for
dating and tracing.
Ionic bond - Answers electron transfer between atoms (example: halite, NaCl).
Covalent bond - Answers electron sharing between atoms (example: diamond).
Metallic bond - Answers electrons shared in a "sea," allowing conductivity (example: copper).
Silicates - Answers mineral group built around SiO₄ tetrahedra; dominate Earth's crust (quartz,
