The Earth's Dynamic Processes and Landforms

Flashcards covering the internal structure of the Earth, the layers of the core, mantle, and crust, and the theories and evidence for continental drift and plate tectonics.

Barysphere

The technical term for the Earth's core, located beneath the mantle at the centre of the Earth.

Outer Core

A $2400$-kilometre-thick band around the inner core with a viscous flowing nature and a density of $10 \text{ g/cm}^3$.

Inner Core

The solid, innermost part of the Earth with a radius of about $960$ kilometres and a density of $13 \text{ g/cm}^3$.

Sial

A term for the continental crust, derived from its high percentage of the mineral silica and the metal aluminium.

Sima

A term for the oceanic crust, named for its high content of the mineral silica and the metal magnesium.

Mohorovicic discontinuity (Moho)

The layer that separates the Earth's crust from the mantle.

Asthenosphere

The upper mantle which behaves like a semi-fluid; its convection currents are the primary cause of crustal fractures and movements.

Mesosphere

The lower mantle, which is more solid and rigid than the upper mantle due to high pressures from overlying layers.

Tectonic activity

The term used to describe the fracture and movement of the Earth's crust.

Peridotite

The type of rock that composes the mantle, consisting primarily of silicate minerals like olivine and pyroxenes.

Gutenberg discontinuity

The boundary layer that separates the Earth's mantle from the core.

Continental Drift

The concept of the gradual movement of continents across the Earth's surface over geological time, moving at an average rate of about $2.5 \text{ cm}$ per year.

Plate Tectonics

The scientific theory reflecting that the Earth's crust is divided into several thin, rigid sections called 'plates' that float on the asthenosphere.

Divergent Boundaries

Locations where plates move apart due to rising currents, allowing magma to rise and create new crust, such as the Mid-Atlantic Ridge.

Convergent Boundaries

Locations where plates move toward each other due to falling currents, often resulting in subduction, mountain building, and volcanic activity.

Subduction

The process at convergent boundaries where one tectonic plate is forced beneath another.

Transform Boundaries

Locations where plates slide past each other horizontally, which can cause significant earthquakes along fault lines like the San Andreas Fault.

Alfred Wegener

The German Meteorologist and Explorer who presented the idea of continental drift in 1912.

Pangaea

A Greek word meaning 'all land,' referring to the single supercontinent that existed before the continents drifted apart.

Panthalassa

The massive ocean that covered the rest of the Earth's surface during the time of the supercontinent Pangaea.

Laurasia

The northern subcontinent formed after Pangaea split, containing present-day Asia, Europe, and North America.

Gondwanaland (Gondwana)

The southern subcontinent formed after Pangaea split, which included South America, Africa, Australia, and Antarctica.

Tethys Sea

The sea that separated the subcontinents of Laurasia and Gondwanaland.

Mesosaurus

A land-based freshwater reptile whose fossils were found in both South America and Africa, serving as evidence for continental drift.

Gondwana Sequence

Identical patterns of rocks and fossils found across continents in the southern hemisphere, indicating they were once joined.