geomorphology & earth landforms section 9 Practice Questions Answers Test with Solutions & More Shortcuts

Answer: (b)

Igneous rocks are formed through the cooling and solidification of magma (or lava). As hot, molten rock rises to the surface, it undergoes changes in temperature and pressure that cause it to cool, solidify, and crystallize.

There are over 700 known types of igneous rock, the majority of which are formed beneath the surface of the Earth’s crust. However, some are also formed on the surface as a result of volcanic activity.

Answer: (d)

Answer: (b)

Loess is Aeolian sediment formed by the accumulation of wind-blown silt, typically in the 20– 50 micrometre size range, twenty per cent or less clay and the balance equal parts sand and silt that are loosely cemented by calcium carbonate.

It is usually homogeneous and highly porous and is traversed by vertical capillaries that permit the sediment to fracture and form vertical bluffs. The word loess, with connotations of origin by wind deposited accumulation, is of German origin and means “loose.” It was first applied to the Rhine River valley loess about 1821.

Answer: (b)

The International Date Line (IDL) is an imaginary line on the surface of the Earth, that runs from the north to the South Pole and demarcates one calendar day from the next.

It passes through the middle of the Pacific Ocean, roughly following the 180° longitude but it deviates to pass around some territories and island groups. From the north, the dateline first deviates to the east of 180° to pass to the east of Russia’s Wrangel Island and the Chukchi Peninsula which is the easternmost part of Russian Siberia.

The dateline then passes through the Bering Strait between the Diomede Islands at a distance of 1.5 km from each island. The line then bends considerably southwest, passing west of St. Lawrence Island and St. Matthew Island.

It then passes midway between Alaska’s Aleutian Islands and Russia’s Commander Islands before returning southeast to 180°. Thus all of Siberia is to the west of the International Date Line, and all of Alaska is to the east of that line.

Answer: (c)

Marble is a non-foliated metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or dolomite. Geologists use the term “marble” to refer to metamorphosed limestone. Marble is a rock resulting from the metamorphism of sedimentary carbonate rocks, most commonly limestone or dolomite rock.

Metamorphism causes variable recrystallization of the original carbonate mineral grains. The resulting marble rock is typically composed of an interlocking mosaic of carbonate crystals. Primary sedimentary textures and structures of the original carbonate rock (protolith) have typically been modified or destroyed.