Geomorphology Questions and Answers

Answer: A

Statements I, II and III are correct, so the answer is I, II and III.

The intensity of an earthquake, the effect it has at a place, is measured on the Mercalli scale (I). The magnitude is a measure of the energy released at the source (II), and it is calculated from the measured amplitude of the seismic waves recorded on a seismograph (III).

Statement IV is wrong. On the Richter scale each whole number is a tenfold increase in the amplitude of the waves, which corresponds to about 32 times more energy released, not a hundredfold increase. That rules out the options including IV.

Answer: A

Volcanic eruptions do not occur in the Baltic Sea.

The Baltic Sea lies on the Baltic (Fennoscandian) Shield, one of the oldest and most stable parts of the earth's crust, far from any plate boundary. There is no volcanic activity in or around it.

The Caribbean Sea is bordered by the volcanic arc of the Lesser Antilles, where volcanoes such as Soufriere Hills on Montserrat are active. The Black Sea and the Caspian Sea lie within the young, tectonically active Alpine-Himalayan belt, and both basins contain mud volcanoes that erupt on the sea floor and along their coasts.

Answer: D

Statements I and III are correct, so the answer is I and III.

Vulcanicity covers all the processes by which molten rock (magma) rises from the interior into the crust or onto the surface (I), together with its cooling and solidification into crystalline or glassy rock once it has been poured out (III).

Statement II is wrong. The greater bulk of the volcanic rock at the earth's surface did not come from volcanoes, the central cones, but from fissure eruptions, in which lava wells out of long cracks and spreads in sheets. The Deccan Traps of India are the classic example.

Answer: D

All three pairs are correct, so the answer is 1, 2 and 3.

• A hanging valley is formed by a glacier, where a tributary glacier's shallower valley is left high above the main valley deepened by a larger glacier.
• A delta is built by a river depositing its load at its mouth.
• Barkhans (barchans) are crescent-shaped sand dunes formed by wind blowing from one direction.

Each landform is a classic example of its agent, so no option leaving a pair out is right.

Answer: A

The record is called a seismogram.

A seismograph is the instrument that detects and records the vibrations of an earthquake, and the graphic trace it produces is the seismogram, showing the arrival of the P, S and surface waves.

The seismograph is the instrument, not the record. Seismology is the science of earthquakes, and tectonic movement is the movement of the earth's plates that causes most earthquakes.

Answer: A

The opening is a volcano.

A volcano is a vent or opening in the earth's crust through which molten rock (lava), rock fragments, ash, steam and other gases escape from below the surface. The term covers both the opening and the landform built up around it.

A crater is the bowl-shaped depression at the top of a volcano, a sink hole is a hollow formed by solution of limestone, and a rift valley is a valley formed where the crust sinks between faults. None of them describes the opening through which eruptions take place.

Answer: D

Such a wave is called a tsunami.

A tsunami is a series of very long sea waves set off by a sudden displacement of the sea floor, most often by an earthquake under the sea, and sometimes by volcanic eruptions or landslides. In deep water it may be barely noticeable, but it rises to great heights on reaching shallow coasts, as in the Indian Ocean tsunami of 2004.

Folding, faulting and fissures are movements or cracks in the earth's crust, not waves.

Answer: C

These raised embankments are called levees.

When a river overflows its banks in flood, it slows down as soon as it leaves the channel and drops the coarsest part of its load close to the channel's edges. Repeated floods build these deposits into natural raised banks, the levees, which run parallel to the river.

The flood plain is the wider flat land covered by the finer deposits beyond the levees, an oxbow lake is a meander cut off from the river, and loops are the bends of the meanders themselves.

Answer: A

Both are true, and the Assertion is the correct explanation of the Statement.

Seismic studies show that the outer core is liquid, because S-waves, which cannot travel through liquid, do not pass through it. The inner core is solid, even though it is hotter, at around 5,000 to 6,000°C.

The reason is pressure. The immense pressure at the centre raises the melting point of the iron-nickel alloy above the actual temperature, so it stays solid. That is exactly why the inner core is solid while the outer core, under less pressure, is liquid. So the Assertion explains the Statement.

Answer: D

Statements iii and iv are correct, so the answer is Only (iii and iv).

iii is correct: seen from above the Sun's north pole, all planets rotate counter-clockwise except Venus, which rotates backwards, and Uranus, which is tilted on its side and rotates retrograde. iv is correct: the planets' orbits lie close to one plane, the plane of the ecliptic, a relic of the flat disc from which the solar system formed.

i is wrong: the common direction is counter-clockwise, not clockwise, and Mars rotates the same way as Earth. ii is wrong: Neptune rotates in the normal direction.