Earth System Basics, Rocks, and Geologic Time

Flashcards covering the fundamentals of minerals, the rock cycle, geologic time scales, Earth's spheres, and internal structure.

Mineral

A substance that has a specific composition and structure.

Rock

A substance that can be a mixture of minerals.

Igneous rocks

Rocks formed from the cooling and solidification of magma (molten rock), with examples including granite and basalt.

Sedimentary rocks

Rocks that accumulate in layers at Earth’s surface, derived from the weathering of preexisting rocks.

Metamorphic rocks

Rocks formed by ‘changing’ preexisting igneous, sedimentary, or other metamorphic rocks through increased heat and pressure, such as gneiss and marble.

Rock Cycle

One of Earth’s subsystems; the loop involving processes by which one rock changes to another on the surface and inside the Earth.

Lithification

The process of cementation and compaction that turns sediment into sedimentary rock.

Relative dating

The practice of placing dates in their proper sequence or order without knowing their age in years.

Precambrian

A collective term for the earliest part of the geologic time scale, comprising about $88\%$ of Earth’s history.

Earth's four spheres

The Hydrosphere, Atmosphere, Biosphere, and Solid Earth.

Earth System Science

An interdisciplinary approach to studying Earth as a system composed of numerous interacting parts or subsystems to solve global environmental problems.

Nebular hypothesis

The theory that Earth and other planets formed at the same time from a rotating cloud called the solar nebula, which began to contract about $5\text{ billion}$ years ago.

Protosun

The pre-Sun located at the center of the flat, disk-shaped solar nebula.

Lithosphere

The ‘sphere of rock’ defined by physical properties, ranging from $5\,km$ to $250\,km$ in depth, which floats on the asthenosphere.

Asthenosphere

The ‘weak sphere’ located below the lithosphere defined by its physical properties.

Mesosphere

The part of the Earth's interior also known as the lower mantle.

Outer core

The liquid layer of Earth's core located at a depth starting at $2900\,km$.

Inner core

The solid innermost part of Earth's core with a radius of $1216\,km$.

Craton

The stable interior of a continent, composed of shields and stable platforms.

Continental margins

Features of the ocean floor that include the continental shelf, continental slope, and the continental rise.

Oceanic ridge system

The most prominent topographic feature on Earth, composed of fractured and uplifted igneous rock.

Geothermal gradient

The measure of heat flow within Earth, cited as $300/km$.