Shaping of the Earth's Surface Vocabulary Flashcards

A set of vocabulary flashcards covering Earth's structure, plate tectonic theories, weathering, erosion, and natural disasters as described in the Chapter 2 lecture notes.

Plate Tectonics

The movement of large pieces of the Earth's outer layer which move horizontally over the semi-fluid asthenosphere, causing phenomena like earthquakes, volcanic eruptions, and mountain formation.

Asthenosphere

The semi-fluid layer of the Earth over which tectonic plates move horizontally.

Continental Drift Theory

A theory proposed by Alfred Wegener suggesting all continents were once a single landmass called Pangaea that later drifted apart.

Pangaea

The name of the single landmass that existed before the continents drifted apart, according to the Continental Drift Theory.

Seafloor Spreading Theory

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

Convection Currents

Circular motion in the mantle created by heat from the Earth's core that acts as the driving force pushing and pulling tectonic plates.

Plate Boundaries

The interactions between tectonic plates, categorized into three types: divergent, convergent, and transform.

Earth's Crust

The solid outer covering of the Earth, varying in thickness from $5$ to $40\,km$, which is thicker under continents and thinner under oceans.

Earth's Core

The innermost and densest shell of the Earth, approximately $3,500\,km$ thick, divided into a liquid outer section and a solid inner section.

Outer Core

The liquid portion of the Earth's core, mainly composed of iron.

Inner Core

The solid portion of the Earth's core made of nickel and iron.

Weathering

The process influenced by changes in temperature and pressure, water freezing in cracks, wind abrasion, and biological actions that break down rocks.

Physical Weathering

The disintegration of rocks without chemical changes, caused by temperature shifts or frost-action.

Chemical Weathering

The dissolution of minerals through chemical reactions with water or air, creating features like cavities and sinkholes.

Biological Weathering

Breaking of rocks caused by living organisms, such as plant roots growing into cracks or burrowing animals loosening the soil.

Erosion

The act of carrying away weathered particles from one place to another by agents such as rivers, glaciers, waves, and winds.

Rivers (as agents of denudation)

Agents that transport large quantities of broken rocks and erode land into gorges and valleys.

Rainwater (as an agent of denudation)

Water that seeps underground to create caves in soluble rocks or reappears as springs.

Glaciers (as agents of denudation)

Moving masses of ice from mountains that create rivers when they melt along their edges.

Upper course of a river

The stage where a river focuses on erosion and transportation, creating landforms like gorges and waterfalls.

Middle course of a river

The stage where a river slows down, forming meanders and fertile flood plains.

Lower course of a river

The final stage where a river deposits alluvium and forms deltas before merging into the sea.

Mountains

High landmasses with sharp slopes, categorized into Fold, Block, and Volcanic types.

Plateaus

Broad, elevated tablelands often rich in mineral deposits, such as the Deccan plateau.

Plains

Relatively flat, low-lying areas formed by river deposits, such as the Great Northern Plains of India.

Natural Disaster

A powerful event caused by Earth's natural processes, such as tectonic movements or climate change, leading to widespread destruction.

Avalanches

The rapid movement of snow down mountain slopes, triggered by rainfall, earthquakes, or temperature changes.

Dust storms

Events caused by strong winds lifting large volumes of dust and sand into the atmosphere, reducing visibility and posing health risks.