Assam ASSEB HSLC Elective Geography flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Mohorovičić discontinuity

The boundary between Earth's crust and mantle where seismic wave velocities increase abruptly; its depth is about 35 km under continents and 5–10 km under oceans.

Rock cycle

The continuous transformation of rock among igneous, sedimentary, and metamorphic types through melting, cooling, weathering, erosion, deposition, lithification, heat, and pressure.

Ox-bow lake

A crescent-shaped water body left when a river abandons a meander loop after cutting across the narrow neck of the loop during a flood.

Lapse rate

The rate at which temperature falls with increasing altitude in the troposphere, averaging about 6.5 degrees Celsius per kilometre; it explains why hill stations are cooler.

Coriolis effect

The apparent deflection of moving air and water caused by Earth's rotation: to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

Orographic rainfall

Rain produced when moist air is forced to rise over a mountain barrier, cooling and condensing on the windward slope while the leeward side lies in a rain shadow.

ITCZ

The Intertropical Convergence Zone, a belt near the equator where trade winds from both hemispheres converge, producing low pressure, ascending air, and heavy convectional rainfall.

Spring tide

The tide of greatest range, occurring at new and full moon when the sun, moon, and Earth align so that solar and lunar gravitational pulls reinforce each other.

Cold ocean current

A current flowing from higher to lower latitudes, such as the Benguela or Humboldt, which cools adjacent coasts, promotes fog, and helps form coastal deserts.

Aquifer

A permeable rock formation, such as sandstone or gravel, that stores and transmits groundwater in usable quantities; it is recharged by infiltration from rainfall.

Demographic transition

A model describing the shift from high birth and death rates through falling death rates to low birth and death rates as a society urbanises and develops.

Push and pull factors

Conditions at the origin that drive people away, such as unemployment or conflict, and attractions at the destination, such as jobs and better services, that draw migrants.

Nucleated settlement

A compact cluster of houses, often around a crossroads, market, fort, or water source, typical of fertile plains where defence and shared services favour grouping.

Shifting cultivation

A subsistence system in which forest is cleared and burned, cropped for a few years, then abandoned to regenerate; also called jhum in North-East India.

Weight-losing industry

An industry whose finished product is lighter or smaller than its raw materials, such as steel or cement, so it tends to locate near the sources of raw material.

Break-of-bulk point

A place where goods are unloaded from one transport mode and transferred to another, often a port or railhead, which commonly becomes an industrial and trading centre.

Majuli

A large river island in the Brahmaputra in Assam, noted for satras and Vaishnavite culture, which has shrunk markedly because of bank erosion and flooding.

Brahmaputra braided channel

The Brahmaputra's wide, multi-channel course in Assam, formed by a very high sediment load deposited as shifting sandbars and chars during the flood season.

Muga silk

A golden-coloured silk produced by silkworms reared in Assam; muga, eri, and pat silks are traditional cottage industries of the Brahmaputra valley.

Siliguri Corridor

A narrow strip of West Bengal linking the North-East states to the rest of India, bordered by Nepal, Bhutan, and Bangladesh, and strategically vital for transport.

Regur soil

Black cotton soil of the Deccan lava region, rich in clay and iron, moisture-retentive and self-ploughing on drying, and well suited to cotton cultivation.

Laterite soil

A leached, iron- and aluminium-rich soil formed under heavy rainfall and high temperature in the Western Ghats and North-East; it hardens on exposure and needs fertiliser.

Western disturbances

Low-pressure systems travelling from the Mediterranean that bring winter rain and snow to north-west India, benefiting wheat and maintaining Himalayan glaciers.

Retreating monsoon

The south-west monsoon's withdrawal from north India between October and November, which brings rain to the Coromandel coast from the Bay of Bengal.

Representative fraction

A scale expressed as a ratio such as 1:50,000, meaning one unit on the map equals 50,000 of the same units on the ground; it is unit-free.

Contour interval

The constant vertical distance between successive contour lines on a map; closely spaced contours mean a steep slope and widely spaced ones a gentle slope.

Six-figure grid reference

A location given by three digits of easting followed by three of northing, locating a point within a 100-metre square on a 1:50,000 topographic sheet.

Magnetic declination

The angle between true north and magnetic north at a place; it must be applied when converting a bearing taken with a compass to a map bearing.

Gradient formula

Gradient equals the vertical difference in height between two points divided by the horizontal distance between them, usually expressed as a ratio or percentage.

Tidal bore

A steep wave of incoming tide that travels upstream in a funnel-shaped estuary or river, such as the Hooghly, because the narrowing channel amplifies the rising water.

Physiological density

The number of people per unit area of cultivable land, which indicates pressure on farmland better than arithmetic density, especially in mountainous or desert regions.

Kaziranga National Park

A floodplain national park in Assam on the Brahmaputra, famous for the greater one-horned rhinoceros and recognised as a World Heritage Site.