INSIGHTS REVISION TEST for Preliminary Exam 2018: Test – 38 (Geography)

Answer: (c)

Justification:

Seismic waves are the vibrations from earthquakes that travel through the Earth; they are recorded on instruments called seismographs. Seismographs record a zig-zag trace that shows the varying amplitude of ground oscillations beneath the instrument. Sensitive seismographs, which greatly magnify these ground motions, can detect strong earthquakes from sources anywhere in the world. The time, location, and magnitude of an earthquake can be determined from the data recorded by seismograph stations.

S waves shadow zone extend from 105⁰. P wave shadow zone extends between 105⁰ to 145⁰. Beyond 145⁰ only P waves are received

At seismic station first waves to arrive are P waves. Then S waves and in the last the surface waves.

Answer: (d)

Justification:

Oceanic trenches are morphological feature of Convergent plate boundaries. For e.g Mariana trench along subduction zone of Philippines plate and Pacific plate

Because of sliding movement along transform boundaries only high intensity earthquakes are possible. It does not lead to mountain orogeny. E.g San Andreas Fault

Answer: (b)

Justification:

Caldera volcanoes are the Extreme Volcanoes. These are the most powerful and catastrophic types of volcanoes in a category by themselves because of the unique way in which they form. This type of volcano is shaped more like an inverse volcano. An enormous magma chamber bulges up beneath the ground from the extremely high pressures of the trapped gases within. Ring-shaped cracks form outward from the magma chamber toward the surface and these act as relief valves for the magma to escape. Once the accumulated pressure has been sufficiently released through a serious of extremely powerful pyroclastic and plinian eruptions, the ground above the magma chamber subsides or caves in, leaving a large depression.

In Shield volcano, Mid-ocean ridges and Flood basalt provinces the lava is not much viscous because of basaltic composition. The eruptions are not violent

Answer: (c)

Justification:

Igneous rock is formed when magma or lava from volcanoes cools. Examples include basalt and granite. Most igneous rock is very hard. They are normally crystalline in structure.They do not occur in strata

Sedimentary rocks are formed over millions of years when sediments (tiny pieces of rocks and animal skeletons) are pressed together at the bottom of seas and rivers.They are distinguished from other rock types in their characteristic layer formation and are termed stratified rocks. Examples include sandstone, coal and chalk. Some sedimentary rocks contain fossils (bones or shells of living things that were buried long ago and have turned to stone).

Metamorphic rocks are formed when other rocks are changed due to heat or pressure. Examples include slate and marble. Metamorphic rocks are very hard but can be damaged by acids like acid rain (on buildings) or even lemon juice (on worktops!).

Answer: (b)

Justification:

Answer: (c)

Justification:

The source region for formation of magnetic field is core of the earth

Asthenosphere and outer outer mantle are part of mantle. Lithosphere includes a part of outer mantle.

Seismic wave diffraction shows a boundary between more and less dense rocks that is commonly taken to be the crust-mantle boundary. It’s called the Mohorovicic discontinuity or Moho for short. It’s usually at 30-40 km depth underneath continents, but can be as deep as 80 km.

Answer: (a)

Justification:

Answer: (d)

Justification :

Answer: (c)

Justification:

Batholith, is large body of intrusive igneous rock believed to have been crystallized at the considerable depth below the earth’s surface.. They are the largest type of pluton. Example of batholith is Idaho batholith which cover surface area of over 15500 kilometer square.
Lopolith these are saucer – shaped features formed beneath the earth’s surface through magma intrusion. Lopolith forms great shallow basin when magma solidifies within the crust a good example is bush veld igneous complex of South Africa which is composed of both granite and basic rock.

Laccolith, this is a sheet intrusion that has been injected between two layers of sedimentary rock. The pressure of magma is powerful enough that the overlying strata are forced upward giving laccolith a dome or mushroom like form with generally planar base. Some laccolith can be found in Madagascar and Utah USA where they has been exposed by erosion.

Phacolith, this is lens shaped pluton that occupy either the crest of an anticline or trough of syncline. A good example of phacolith can be seen seen in Corndon hills in Shropshire United Kingdom.

Answer: (d)

Justification:

Natural Levees    – Fluvial

Esker                  – Glacial

Uvala                 – Karst

Barchan             – Aeolin

Answer: (a)

Justification:

The Dead Sea Transform (DST) fault system, also sometimes referred to as the Dead Sea Rift, is a series of faults that run from the Maras Triple Junction (a junction with the East Anatolian Fault in southeastern Turkey) to the northern end of the Red Sea Rift (just offshore of the southern tip of the Sinai Peninsula). The fault system forms the transform boundary between the African Plate to the west and the Arabian Plate to the east.

Answer: (c)

Justification:

The Earth’s outer crust is made up of a series of tectonic plates that move over the surface of the planet. In areas where the plates come together, sometimes volcanoes will form. Volcanoes can also form in the middle of a plate, where magma rises upward until it erupts on the seafloor, at what is called a “hot spot.”

The Hawaiian Islands were formed by such a hot spot occurring in the middle of the Pacific Plate. While the hot spot itself is fixed, the plate is moving. So, as the plate moved over the hot spot, the string of islands that make up the Hawaiian Island chain were formed.

Answer: (d)

Justification:

Nearly 46.6% of total crust of earth is composed of oxygen and 27.72% by silicon

The P waves travel fastest through outer mantle. Seismic velocities depend on the material properties such as composition, mineral phase and packing structure, temperature, and pressure of the media through which seismic waves pass.

Seismic waves travel more quickly through denser materials and therefore generally travel more quickly with depth. Anomalously hot areas slow down seismic waves. Seismic waves move more slowly through a liquid than a solid.

Molten areas within the Earth slow down P waves and stop S waves because their shearing motion cannot be transmitted through a liquid. Partially molten areas may slow down the P waves and attenuate or weaken S waves.

Answer: (c)

Justification :

In desert and arid regions wind is an important agent of weathering. Abrasion through wind action is important mode of erosion.

Carbonation and hydration are more common in humid areas

Frost action is common in tundra and temperate regions.

Answer: (c)

Justification:

Canberra is located on Murrumbidgee river

Answer: (c)

Answer: (b)

Answer: (c)

Answer: (d)

Answer: (b)