Earth's Tectonic Plates and Volcanic Activity

Flashcards covering key vocabulary terms related to tectonic plates and volcanic activity.

Plate Boundary

The area where the edges of two tectonic plates meet.

The main plates

There are seven primary crustal plates and several smaller ones. The are

North American, South American, African, Antarctic, Indo-Australian, Eurasian, and Pacific plates.

Plates tectonics

The Earth’s surface is not a continuous layer. The lithosphere is broken up into several large pieces called crustal plates or tectonic plates. These large segments of the crust and upper mantle float on the denser semi-molten rock beneath them and move very slowly across the surface of the planet. Plate tectonics can be described as the study of crustal plates and how their movement affects the Earth’s

surface.

Convergent Boundary

A boundary where two plates move toward each other, causing collisions, earthquakes, and volcanic activity.

Subduction

The process where one plate is pushed under another at a convergent boundary.

Ocean Trench

A V-shaped depression formed at convergent boundaries where an oceanic plate is subducted.

Island Arc

A chain of islands formed by volcanic activity due to the subduction of one oceanic plate beneath another.

Divergent Boundary

A boundary where two tectonic plates move away from each other, allowing magma to rise and create new crust.

Mid-Atlantic Ridge

A divergent plate boundary in the Atlantic Ocean where new oceanic crust is formed.

Transcurrent Boundary

Also known as transform boundary, where two plates slide past each other, often causing earthquakes.

Extrusive Volcanic Features

Volcanic features formed on the Earth's surface from eruptions.

Composite Cone

A type of volcano formed from layers of ash and lava, typically found at convergent boundaries.

Basalt Plateau

A wide flat plateau formed by large amounts of basalt lava that cover extensive areas.

Caldera

A large volcanic depression formed when a volcano's magma chamber empties after a massive eruption.

Volcanic Plug

A mass of hardened magma that forms inside a volcano's vent.

Sill

A horizontal sheet of solid rock formed when magma flows between rock layers.

Dyke

A vertical sheet of rock formed when magma cools and hardens while moving towards the surface.

Viscous Lava

Thick lava that flows slowly and can erupt explosively, leading to steep-sided volcanoes.

Basic Lava

Fluid lava that flows easily, producing broad, gently sloped shield volcanoes.