Theme II: Shaping of The Earth's Surface

A set of vocabulary flashcards based on the lecture notes regarding Earth's surface processes, tectonic theories, interior structure, and natural disasters.

Plate Tectonics

A scientific theory explaining the movement of large pieces of the Earth's outer layer, known as tectonic plates, horizontally over the asthenosphere.

Lithosphere

The Earth's outer layer, divided into large and small plates that move over the semi-fluid layer beneath them.

Asthenosphere

The semi-fluid layer of the Earth located directly beneath the lithosphere.

Pangaea

A single massive landmass that Alfred Wegener suggested once contained all joined continents before they drifted apart.

Seafloor Spreading Theory

A theory proposed by Harry Hess and Robert S. Dietz stating that new oceanic crust forms at mid-ocean ridges and pushes older crust away.

Convection Currents

Circular motions in the mantle created by heat from the Earth's core that drive tectonic plate movement.

Crust

The solid outer covering of the Earth whose thickness varies from $5$ to $40$ kilometres.

Mantle

A thicker layer of rock between the crust and the core, with an average thickness of about $2,900\,km$.

Mohorovicic Discontinuity

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

Outer Core

The layer of the Earth's core that is mainly composed of iron and exists in a liquid state.

Inner Core

The innermost part of the Earth composed of nickel and iron; it behaves like a solid due to extremely high pressure.

Weathering

The process by which rocks on the Earth's surface are broken into smaller pieces in situ (in the same place).

Exfoliation

A physical weathering process common in granitic rocks where the outer layers peel away due to expansion and contraction from temperature changes.

Frost-action

A weathering process where water enters rock cracks, freezes, expands, and eventually breaks the rock apart.

Chemical Weathering

The disintegration of rocks due to chemical reactions with water or air, producing features like sinkholes and caverns.

Biological Weathering

The breaking up of rocks caused by the actions of plants, animals, and humans.

Erosion

The act of carrying away weathered particles from one place to another by agents like water, wind, or ice.

Mass Movements

Downward movements of soil, rocks, or debris caused by gravity, common in mountainous regions.

Denudation

A term that literally means making nude or bare, referring to the combined processes that wear away the Earth's surface.

Gorge

A narrow valley with steep walls formed when a river flows through an area of hard rocks.

Meanders

Big loops formed by a river as it swings from side to side across a flat plain.

Delta

A fan-shaped landform made of alluvial deposits found at the mouth of a river before it enters the sea.

Continental Glaciers

Thick ice sheets covering large areas, exceeding thousands of square kilometres, generally found in Polar Regions.

Fold Mountains

Mountains created by internal Earth movements that cause the crust to fold, such as the Himalayas or the Alps.

Block Mountains

Mountains formed when large masses of land are broken and displaced vertically, such as the Vosges mountains.

Plateau

A broad, level stretch of upland that rises sharply above the neighbouring lowland, also known as a tableland.

Seismograph

The scientific instrument used to measure the intensity of earthquakes.

Richter Scale

The scale used to measure the magnitude of earthquakes.

Glacial Lake Outburst Flood (GLOF)

A sudden and massive release of water from a glacial lake caused by the failure of a natural dam made of ice or moraines.

Duststorms

Environmental disasters where strong winds lift large amounts of dust and sand from dry, bare soil into the atmosphere.