Geology and Earth Science Test 1 Study Guide

Vocabulary study set based on Test #1 Study Guide covering scientific methodology, mineralogy, igneous/sedimentary/metamorphic petrology, structural geology, stratigraphy, geologic historical events, and energy resources.

Hypothesis

A testable prediction about a natural phenomenon.

Theory

A well-supported explanation of aspects of the natural world based on a body of evidence.

Scientific Law

A concise statement that describes a natural pattern or relationship, often expressed mathematically.

Mineral

A naturally occurring, inorganic solid with a definite chemical composition and crystalline structure.

Cation

A positively charged ion formed when an atom loses electrons.

Anion

A negatively charged ion formed when an atom gains electrons.

Silicates

The most abundant mineral class in the Earth's crust, including minerals like feldspars, quartz, pyroxenes, amphiboles, micas, and olivine.

Asbestos

A set of minerals prized for being heat resistant, strong, flexible, chemical resistant, and insulating, but known to cause asbestosis, lung cancer, and mesothelioma.

Moho

The Mohorovičić discontinuity; the boundary between the Earth's crust and mantle.

Outer Core

The liquid mechanical layer of the Earth composed primarily of iron and nickel.

Inner Core

The solid mechanical layer at the center of the Earth composed of iron and nickel.

Rock

A naturally occurring solid aggregate of one or more minerals.

Igneous Rock

Rock formed through the cooling and solidification of molten rock (magma or lava).

Magma

Molten rock located underground beneath the Earth's surface.

Lava

Molten rock that breaks through the Earth's surface.

Ore

A naturally occurring rock or mineral that contains valuable material that can be mined for a profit.

Conflict Diamond

Also known as a blood diamond; a diamond mined in a war zone and sold to finance armed conflict.

Igneous Rock Classification Chart

A diagram categorizing igneous rocks by mineral composition, color, percentage of mafic minerals, cooling temperature, and grain texture.

Clastic Sedimentary Rock

Sedimentary rock composed of weathered fragments and grains of pre-existing rocks, such as sandstone, shale, breccia, and conglomerate.

Chemical Sedimentary Rock

Sedimentary rock formed from dissolved minerals that precipitate out of solution, such as rock salt, rock gypsum, and chert.

Biochemical / Organic Sedimentary Rock

Sedimentary rock formed from organic remains of organisms, such as coal, chalk, and fossiliferous limestone.

Proximal Sediments

Sediments deposited near their source area, characterized by larger grain size and more angular shape.

Distal Sediments

Sediments transported far from their source area, characterized by smaller grain size and well-rounded shape.

Progression of Coal Formation

The sequential development stages of coal starting from Peat to Lignite, Bituminous, and Anthracite.

Foliated Metamorphic Rock

Metamorphic rock that displays planar alignment of mineral grains formed under directed pressure/compression conditions.

Slate

A low-grade foliated metamorphic rock with fine mineral grain alignment.

Phyllite

A medium-low grade foliated metamorphic rock.

Schist

A medium-high grade foliated metamorphic rock with visibly aligned platy minerals.

Gneiss

A high-grade foliated metamorphic rock with distinct compositional banding and large mineral crystals.

Non-Foliated Metamorphic Rock

Metamorphic rock formed without directed stress, resulting in non-aligned mineral textures (e.g., Marble, Quartzite, Hornfels, Blueschist).

Normal Fault

A fault where the hanging wall moves downward relative to the footwall, caused by tensional stress.

Reverse Fault

A fault where the hanging wall moves upward relative to the footwall, caused by compressional stress.

Strike-Slip Fault

A fault where rock blocks slide horizontally past one another, caused by shear stress.

Stress vs. Strain

Stress is the force applied per unit area, whereas strain is the resulting deformation or change in shape.

Footwall

The block of rock located below an inclined fault plane.

Hanging Wall

The block of rock located above an inclined fault plane.

Relative Time

Determining the chronological sequence of geological events without assigning precise numerical ages.

Absolute Time

Determining the specific numerical age of a geological event or rock unit in years.

Index Fossil

A fossil of an organism that was widespread geographically, existed for a short geological duration, and is easily recognizable.

Half-Life

The duration of time required for half of the parent radioactive isotopes in a sample to decay into daughter isotopes.

Age of the Earth

Approximately $4.54\text{ Ga}$ ($4.54\text{ billion years}$).

Habitat

The specific physical environment in which an organism lives.

Ecological Niche

The specific functional role and position an organism occupies within its ecosystem.

End-Cretaceous Extinction (K-Pg)

The mass extinction event that resulted in the demise of non-avian dinosaurs.

End-Permian Extinction

The severe extinction event known as "The Great Dying", marking Earth's most disastrous mass extinction.

Phanerozoic Eon

The current geological eon characterized by abundant, easily visible fossil life.

Cambrian Period

The geological period that marks the sudden rapid diversification and explosion of animal life.

Time Units (Ga, Ma, ka)

$Ga$ = Giga-annum (billion years ago), $Ma$ = Mega-annum (million years ago), $ka$ = Kilo-annum (thousand years ago).

Three Pillars of Sustainability

The core aspects of sustainable development: environmental, economic, and social.

Carboniferous Period

The geologic period responsible for depositing vast amounts of carbon organic material into the ground to create modern fossil fuels.

Nuclear Fission

The nuclear reaction process where a large atomic nucleus splits into smaller fragments, releasing significant energy.

Renewable Energy Source

An energy resource that naturally replenishes itself over short timescales, such as solar, wind, and hydro power.

Non-Renewable Energy Source

An energy resource present in finite supply that cannot be rapidly replenished, such as coal, oil, natural gas, and uranium.