Geology Unit 2 Vocabulary Study Guide

Flashcards for Geology Unit 2 vocabulary covering rock formation, weathering, plate tectonics, Earth's interior structure, volcanoes, and seismic concepts.

Metamorphic rocks

Rocks formed when existing rock is changed by heat and pressure without melting.

Igneous rocks

Rocks formed when magma or lava cools and hardens.

Sedimentary rocks

Rocks formed when sediment is deposited, compacted, and cemented into rock.

Foliation

The layered or banded appearance of some metamorphic rocks caused by pressure aligning minerals.

Weathering

The breakdown of rocks at Earth's surface.

Erosion

The movement/transport of weathered rock and sediment.

Deposition

The process in which transported sediment is dropped or deposited in a new location.

Lithification

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

Clastic sedimentary rocks

Sedimentary rocks made from pieces of other rocks.

Chemical sedimentary rocks

Sedimentary rocks that form when dissolved minerals precipitate from water.

Organic/biochemical sedimentary rocks

Sedimentary rocks formed from the remains or activity of organisms.

Theory of Continental Drift

Early 20th-century theory proposed by Alfred Wegener stating that continents move, supported by puzzle-like continental fit, matching fossils, and matching rock layers/mountain ranges across oceans.

Mid-ocean ridges

The longest chain of mountains on Earth, located on the seafloor, where new crust forms as seafloor spreading occurs.

Transform boundary

A plate boundary where plates slide horizontally past each other, forming faults such as the San Andreas Fault and causing earthquakes.

Divergent boundary

A plate boundary where plates move away from each other, forming mid-ocean ridges, rift valleys, and new crust, as well as causing earthquakes and volcanic activity.

Convergent boundary: Continental vs. Continental

A plate boundary where two continental plates move toward and collide with each other, forming mountain ranges and causing earthquakes.

Convergent boundary: Oceanic vs. Continental

A plate boundary where the denser oceanic plate subducts beneath the continental plate, forming deep-ocean trenches, volcanic mountain ranges, earthquakes, and volcanoes.

Convergent boundary: Oceanic vs. Oceanic

A plate boundary where one oceanic plate subducts beneath another, forming deep-ocean trenches, volcanic island arcs, earthquakes, volcanoes, and possible tsunamis.

Convection currents

Circular movement of material in the mantle driven by internal heat, where material expands and becomes less dense when heated (rising) and cools and becomes denser near the surface (sinking).

Asthenosphere

The mantle layer of Earth that contains convection currents.

Lithosphere

The layer of Earth that consists of the crust and the rigid uppermost mantle.

Hot spot

An unusually hot area of the mantle where magma rises through a tectonic plate, capable of forming volcanic island chains in the ocean as the plate moves over it.

Cinder cone volcano

A small, steep-sided volcano made mostly of volcanic fragments/cinders.

Shield volcano

A very broad volcano with gentle slopes, formed by runny lava that spreads far.

Composite volcano (Stratovolcano)

A tall and steep volcano built from alternating layers of lava, ash, and other volcanic material, capable of explosive eruptions.

Pyroclastic flow

The most dangerous part of a volcano; a very hot, fast-moving mixture of volcanic gas, ash, and rock that can rapidly move down a volcano.

Elastic Rebound Theory

Theory explaining that stress builds up in rocks along a fault, and when the rocks suddenly slip, they release stored elastic energy, producing an earthquake.

P waves

Primary seismic waves; the fastest waves that travel through solids and fluids using push-pull/compressional motion.

S waves

Secondary seismic waves; slower waves that travel through solids only using shearing/side-to-side motion.

Epicenter

The point on Earth's surface directly above the earthquake focus.

Focus

The underground point where an earthquake begins.

Depth

The distance from Earth's surface down to the earthquake focus.