Overview of Terrestrial and Jovian Planets and Earth Systems

Meteorites

Fragments of meteoroids that survive through Earth's atmosphere and reach the surface.

Hydrosphere

All of Earth's water, including oceans, rivers, and lakes.

Geosphere

The solid part of Earth, consisting of rocks and minerals.

Lithosphere

The rigid outer layer of Earth, including the crust and upper mantle.

Cryosphere

The frozen water portion of Earth, including glaciers and ice caps.

Uniformitarianism

The principle that the same geological processes occurring today have always occurred in the past.

Catastrophism

The idea that Earth's features formed quickly due to catastrophic events.

Scientific Method

A systematic process of observation, hypothesis formation, experimentation, and conclusion in science.

Mineral

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

Atomic Structure

The arrangement of protons, neutrons, and electrons in an atom.

Valence Electrons

Electrons in the outer shell of an atom, involved in chemical bonding.

Terrestrial Planets

Small, rocky planets (Mercury, Venus, Earth, Mars) located closer to the Sun.

Jovian Planets

Large, gas giants (Jupiter, Saturn, Uranus, Neptune) located farther from the Sun.

Oort Cloud

A distant region surrounding the solar system, filled with icy bodies and the source of long-period comets.

Kuiper Belt

A region beyond Neptune that contains small icy objects, including dwarf planets like Pluto.

Asteroids

Rocky bodies primarily found in the asteroid belt between Mars and Jupiter.

Comets

Icy bodies that release gas and dust, forming a glowing tail as they approach the Sun.

Atmosphere

The layer of gases surrounding Earth.

Biosphere

The zone of life on Earth, containing all living organisms.

Atomic Number

The number of protons in the nucleus of an atom.

Atomic Mass

The total number of protons and neutrons in an atom's nucleus.

Ions

Atoms that have gained or lost electrons, giving them a positive or negative charge.

Isotopes

Atoms of the same element with different numbers of neutrons.

Bonding

The joining of atoms to form molecules, including ionic, covalent, and metallic bonds.

Ionic Bonding

A type of bonding where electrons are transferred between atoms.

Covalent Bonding

A bond where electrons are shared between atoms.

Metallic Bonding

A bond where electrons are free to move among metal atoms.

Moh's Scale of Hardness

A scale ranking minerals from softest (1, talc) to hardest (10, diamond).

Bowen's Reaction Series

A model describing the order in which minerals crystallize from cooling magma.

Mafic Minerals

Dark-colored, magnesium- and iron-rich minerals (e.g., olivine).

Felsic Minerals

Light-colored, silica-rich minerals (e.g., quartz, feldspar).

Silicates

Minerals that contain silicon and oxygen, forming the largest mineral group.

Tetrahedron Structures

The building block of silicate minerals, made of one silicon atom and four oxygen atoms.

Evaporites

Minerals formed from the evaporation of water, such as halite and gypsum.

Magma

Molten rock beneath Earth's surface.

Extrusive Rocks

Igneous rocks that cool and solidify on Earth's surface.

Intrusive Rocks

Igneous rocks that cool and solidify beneath Earth's surface.

Basaltic Magma

Low-silica magma that is fluid and forms basalt when cooled.

Silicic Magma

High-silica magma that is viscous and forms granite when cooled.

Cooling Rate

Determines crystal size in igneous rocks; slow cooling leads to large crystals, and fast cooling leads to small or no crystals.

Aphanitic Texture

Fine-grained texture formed by rapid cooling of lava.

Phaneritic Texture

Coarse-grained texture formed by slow cooling of magma.

Glassy Texture

A texture with no crystals, formed by very rapid cooling of lava (e.g., obsidian).

Felsic vs. Mafic Rocks

Felsic rocks are rich in silica and light-colored (e.g., granite), while mafic rocks are rich in magnesium and iron and darker (e.g., basalt).

Diagenesis

The process that converts loose sediments into solid rock through compaction and cementation.

Lithification

The process of turning loose sediment into solid rock through compaction and cementation.

Clastic Sedimentary Rocks

Rocks made from fragments of other rocks, classified by grain size (e.g., sandstone, shale).

Non-Clastic Sedimentary Rocks

Rocks formed by chemical precipitation (e.g., limestone, evaporites).

Sorting

The distribution of grain sizes in a sedimentary rock.

Roundness

The degree to which sediment grains have been rounded by transport.

Compaction

The process by which sediment grains are squeezed together by the weight of overlying layers.

Cementation

The process in which dissolved minerals precipitate out of water and fill the spaces between sediment grains, binding them together.

Grain Size

The size of sediment particles, which helps classify clastic sedimentary rocks.

Sandstone

A clastic sedimentary rock composed of sand-sized particles.

Shale

A fine-grained clastic sedimentary rock composed of clay-sized particles.

Conglomerate

A coarse-grained clastic sedimentary rock with rounded gravel-sized clasts.

Breccia

Similar to conglomerate, but with angular clasts.

Limestone

A chemical sedimentary rock composed mainly of calcium carbonate, often formed from marine organisms.

Coal

A biochemical sedimentary rock formed from compressed plant material.

Sedimentary Structures

Features such as cross-bedding, ripple marks, and graded bedding that provide clues to the depositional environment.

Facies

A body of sediment with distinctive characteristics that reflect the conditions of its deposition.

Sedimentary Environments

Settings where sediment is deposited (e.g., rivers, lakes, deserts, oceans).

Mechanical Weathering

The physical breakdown of rocks without chemical change (e.g., frost wedging, exfoliation).

Chemical Weathering

The breakdown of rocks through chemical reactions (e.g., oxidation, hydrolysis, dissolution).

Frost Wedging

The process by which water freezes in cracks of rocks, expanding and breaking the rock apart.

Exfoliation

The process where rock layers peel away due to pressure release.

Oxidation

A type of chemical weathering where oxygen reacts with minerals, causing rusting (common in iron-rich rocks).

Dissolution

The process by which minerals dissolve in water (e.g., limestone dissolving in acidic rain).

Hydrolysis

The chemical breakdown of minerals by water, often forming clay minerals.

Spheroidal Weathering

A type of chemical weathering that rounds the corners of rocks.

Soil

A mixture of weathered rock, organic material, air, and water that supports plant life.

Soil Horizons

Layers of soil, including topsoil (O horizon) and subsoil (B horizon).

Regolith

The layer of loose, weathered material covering solid rock.

Humus

Organic material in soil, formed from decayed plant and animal matter.

Soil Profile

A vertical section of soil showing its different layers or horizons.

Acid Rain

Rainwater that contains acids from air pollution, which accelerates the chemical weathering of rocks.

Rainforest Soils

Typically poor in nutrients due to heavy rainfall, which leaches minerals from the soil.

Preserving Soil

Methods to prevent soil erosion, such as planting vegetation and using cover crops.

Metamorphism

The process by which rocks are altered in structure or mineral composition by heat, pressure, and chemically active fluids without the rock melting.

Heat

One of the main agents of metamorphism, which causes minerals in a rock to recrystallize and new minerals to form without the rock melting. Heat typically comes from Earth's interior or nearby magma.

Pressure

Another agent of metamorphism. Pressure can be confining (equal pressure in all directions) or differential (unequal pressure, which can cause deformation).

Deformation (Plastic Deformation)

The process where rocks change shape under pressure without fracturing. This happens during metamorphism, particularly when differential pressure is applied.

Geothermal Gradient

The rate of temperature increase with depth in Earth's crust. Higher geothermal gradients lead to more intense metamorphism.

Confining Pressure

Pressure applied equally in all directions on a rock, which compresses it without causing deformation.

Differential Pressure

Unequal pressure in different directions, often associated with tectonic forces, which can lead to the formation of foliated textures in metamorphic rocks.

Parent Rock (Protolith)

The original rock from which a metamorphic rock forms. For example, limestone is the parent rock of marble.

Regional Metamorphism

Metamorphism affecting rocks over large areas, typically due to high pressure and temperatures from tectonic forces (e.g., mountain building).

Contact Metamorphism

Occurs when rocks are heated by nearby magma or lava, typically resulting in non-foliated rocks.

Hydrothermal Metamorphism

Occurs when hot, chemically active fluids interact with a rock, often altering its mineral composition.

Dynamic Metamorphism

Associated with fault zones, where rocks are subjected to high pressure and shear but low temperatures.

Foliated Texture

A texture in metamorphic rocks where minerals are aligned due to differential pressure, forming layers or bands. Examples:

Slatey Cleavage

Fine-grained foliation seen in slate, allowing the rock to split into thin layers.

Schistosity

A type of foliation where larger, visible platy minerals (such as mica) are aligned in the rock (e.g., schist).

Gneissic Banding

Alternating light and dark mineral bands in a high-grade metamorphic rock (e.g., gneiss).

Non-Foliated Texture

A texture in metamorphic rocks where mineral grains are not aligned in layers. Examples:

Marble

Formed from the metamorphism of limestone, it has an interlocking texture of calcite crystals and is non-foliated.

Quartzite

Formed from the metamorphism of quartz sandstone, it is very hard and also non-foliated.

Slate

A fine-grained, foliated metamorphic rock formed from shale. It has slatey cleavage and splits easily into thin sheets.

Schist

A medium- to coarse-grained metamorphic rock with schistosity, characterized by the presence of platy minerals like mica, which give the rock a shiny appearance.

Gneiss

A high-grade foliated metamorphic rock characterized by alternating light and dark mineral bands (gneissic banding). Gneiss forms under intense heat and pressure.