Shaping of the Earth’s Surface Flashcards

Practice flashcards covering the key terms, Earth layers, tectonic theories, landform types, and natural disasters described in Chapter 2 of Plate Tectonics and Shaping of the Earth’s Surface.

Plate Tectonics

An important theory, given by W.J. Morgan, that explains the outermost layer of the Earth as broken into several large and small pieces called tectonic plates that move slowly over the molten mantle.

Lithosphere

The rigid outer layer of the Earth that includes the crust and the upper mantle, approximately $100\,km$ thick.

Asthenosphere

A hot, mobile, semi-molten layer of partially molten rock beneath the lithosphere, approximately $200\,km$ thick, which allows tectonic plates to move.

Crust

The outermost layer of the Earth, varying in thickness from $30\text{--}40\,km$ under continents to $5\text{--}7\,km$ under the ocean.

Mantle

The mostly solid layer between the crust and the Earth’s outer core, approximately $2900\,km$ thick.

Outer Core

A fluid layer mainly consisting of iron and nickel, approximately $2200\,km$ thick.

Inner Core

A solid, hot spinning metal ball that is the densest part of the Earth, located at a depth of approximately $6375\,km$ with a thickness of $1250\,km$.

Convergent Boundary

A plate boundary where two plates move towards each other; it can form fold mountains like the Himalaya or lead to volcanic activity and earthquakes when oceanic plates sink beneath continental plates.

Divergent Boundary

A plate boundary where plates move away from each other, allowing magma to rise and form new crust, such as the Mid-Atlantic Ridge.

Transform Boundary

A plate boundary where plates slide past each other without creating or destroying crust, often causing earthquakes like those along the San Andreas Fault.

Ring of Fire

An area around the Pacific Ocean where most earthquakes and volcanoes occur along plate boundaries.

Bhūkampa

An early term for earthquakes meaning the shaking of the Earth, described in the Bṛihatsaṁhitā by Varāhamihira.

Weathering

The process through which rocks on the Earth’s surface break down into smaller pieces due to temperature changes, chemicals, or biological agents, without involving movement of the material.

Erosion

The process by which soil, rocks, and surface materials are worn away and carried from one place to another by natural agents like water, wind, ice, or waves.

Contouring

A water conservation technique involving continuous contour trenches (CCT) dug along the lines of a hillside to slow down rainwater and prevent soil erosion.

Bunding

Earthen embankments built along contour lines to slow surface run-off, reduce soil erosion, and increase water infiltration.

Terracing

A soil conservation practice that creates a series of level or gently sloping steps on a hillside to prevent soil erosion.

Agents of Gradation

Natural forces including running water, glaciers, wind, waves, and groundwater that wear down, transport, and deposit materials to level the Earth’s surface.

Meander

A winding curve or bend in the middle or lower course of a river formed due to lateral erosion and deposition.

Delta

A fan-shaped or triangular landform formed at the mouth of a river where it deposits sediments before flowing into a sea, ocean, or lake.

Stack

An isolated pillar of rock left standing in the sea after a coastal arch collapses due to erosion.

Fjord

A deep, narrow inlet created when the sea floods a valley previously carved by a glacier.

Moraine

A landform created by the deposition of rocks, soil, and debris (till) carried and left behind by a melting glacier.

Yardang

A streamlined rock ridge carved by wind erosion in desert environments.

Dunes

Hills or ridges of sand formed by the wind, categorized into types such as barchan, longitudinal, star, and parabolic.

Karst Topography

Unique landforms created in areas of limestone or soluble rocks through chemical weathering and erosion by underground water.

Stalactite

An icicle-shaped formation hanging from the ceiling of a cave created by underground water.

Sinkhole (Doline)

A depression formed when the ground collapses into an underground cavity created by water dissolving rock.

GLOF (Glacial Lake Outburst Flood)

A destructive flood caused by the sudden release of large volumes of water from a glacial lake due to melting, heavy rain, or dam failure.

Dust Storm

A phenomenon caused by strong winds lifting loose, dry soil and sand into the air, common in desert and semi-arid regions.