1) Write notes on Lithosphere.
Litho is a Greek word, which
means stone. Accordingly the lithosphere is the part of the earth, which is
solid crust. The thickness of lithosphere is approximately 50 km. The crust
thickness is not the some at all places. It is thicker in the continent and
thinner on the ocean floors. Lithosphere is a source of various minerals. It
contains variety of landforms such as mountains.plateous valleys, plains.
2) What is meant by NIFE?
The central part of the earth is
called Core or barysphere. It has thickness of 2900km.This layer is made of
very hard mineral like Nickel (Ni) and iron (Fe) and so it is called NIFE (Ni +
Fe). Here there is intense heat and pressure and this region is elastic and
viscous in nature.
3) Distinguish between SIAL and SIMA.
The upper most layers is called
the crust of the earth. It has a thickness of 50 km and thus the crust is made
of two layers. Silica (si) and Aluminium (Al) are the elements found in the
first layer. Therefore this layer is called SIAL (Si + Al). This layer is also
called 'Granitic
layer.'
Below the SIAL ties a layer
called SIMA which composes of silica (Si) and Magnesium (Mg). This layer is
also called Basaltic layer.
4) What are plates?
The surface of the earth is the
crust of the earth. It is made of interlocking pieces called plates. The
continents and oceans rest in these places and are separated by wide cracks.
The plates move constantly.
5) What is meant by atmosphere?
The outer gaseous part of the
earth starting from the surface and extending as far as 700 km and even beyond
is termed atmosphere.It makes only about one-million part of the total mass of
the earth.
6) Define sea floor spreading.
Divergent
boundaries occur at Oceanic ridges. In the process of plate separation, the
magma rises up from the asthenosphere and fills the gap their created. In this
way new crust is created along the trailing edges of the diverging plates. This
phenomenon is called sea floor spreading.
7) What are
the subdivisions in geology?
The subdivisions are:
a) Physical
geology
b)
Geomorphology
c) Mineralogy
d) Petrology
e) Historical
geology
f) Economic
geology
g) Geohydrology
h) Engineering
geology
i) Metrology
8.What is
meant by engineering geology?
Engineering
geology may be defined as that of applied sciences which deals with the
application of geology for a safe, stable land economical design and
construction of a civil engineering project.
9) Define seismology.
Seismology is a branch of
geophysics that deals with the study of elastic waves within the body of the
earth during an earthquake.ie.The study of earthquake is called seismology.
10) Give the two types of discontinuity.
There are
two important discontinuities:
Mohorovocic or Moh discontinuity Gutenberg or Oldharm
discontinuity
11)
Define denudation.
It is general term used when the
surface of the earth is worn away by chemical as well as mechanical actions of
physical agents and the lower layers are exposed. This happens when the rocks
were exposed for a sufficient length of time to the attacks of physical agents.
12) What is mean by continental crust?
The continental crust consists of
two layers separated by a well-defined discontinuity known as conard
discontinuity. The layers have been defined on the basis of seismic waves
velocities and densities.
In the upper layer the velocity
of seismic waves corresponds to the velocity found by experimental to be
characteristic of granite. Hence they are called as Granitic or sialic layer.
13) What is mean by physical weathering?
It is a physical breakdown of
rock masses under the attack of certain atmospheric agents. A single rock block
is broken gradually into smaller irregular fragments and then into particles of
still smaller dimensions. Temperature variations are irresponsible to a great
extent of physical weathering.
15) Define deflation.
Deflation is the process of
simply removing the loose sand and dust sized particles from an area, by fast
moving winds. Wind deflation can successfully operate in comparatively dry
regions with little pr no rainfall and where the mantle is unprotected due to
absence of vegetation.
16) What are Barchans?
The barchans are crescent or half
moon shaped dunes of variable size. Their 'horns' point in
the downward direction. Their height may vary from 15-200 mts. And width from a
few to 1000s meter. They have a gentle windward slope and steeper leeward slope.
17) Define
the terms
i) Focus
ii) Epicenter
Focus:
The exact
spot underneath the earth's surface, at which an earthquake originates, is known
as its focus.
Epicenter:
The earthquake then moves in the
from of wave which are spread in all directions. These waves first reach the
point at the surface, which is immediately above the focus or origin of the
earthquake. This point is called epicenter.
18) What are the causes of earthquake?
The
earthquake may be caused due to various reasons:
Earthquakes due to superficial movements.
Earthquake due to volcanic eruptions. Earthquake due to
folding or faulting
19)
Define aquifer and the names the types of
aquifers.
Groundwater occurs in permeable
geologic formations is known as aquifers.i.e formations having structures hat
permit appreciable water to move through them under ordinary field
conditions.Aquifers may be classes as unconfined and confined, depending upon the
presence or absence of a water table.
20) What do you understand by spheroidal
weathering?
When weathering occurs, part of
the disintegrated rock material is carried away by running water or any other
transporting agent. Some of them are left on the surface of the bedrock as
residual boulders. These boulders are then rounded off to spheroidal cores by
the simultaneous attack of eroding agents on all sides. It is often seen that
these boulders have an onion like structure. This kind of weathering is called
spheroidal weathering.
21) Write short notes on:
*)
Porosity
*)
Permability
Porosity:
The portion of a rock or soil not
occupied by solid mineral matter may be occupied by ground water. These spaces
are known as voids, interstices, pores or pore space. The interstices can act
as ground water conduits; they are characterized by their size, shape,
irregularity, and distribution.
Permability:
The groundwater is stored in the
pores of a rock and will hence be available in the groundrocks. The porosity of
the rock, thus defining the maximum amount of water that can be stored in the
rock. This is called permeability.
22) What is mean by water table?
The depth to upper surface of
zone of saturation in free ground water is called water table. In other words,
a static level of water in wells penetrating the zone of saturation is called
water table.
23) What are the movements of the oceans?
There are
three movements of oceans:
i) Waves
ii) Tides
iii) Currents.
Waves are only the rise and fall
of water caused by the action of the winds. There is no movement forward. These
are at the surface and not at great depth.
Currents are rivers in the sea.
The water moves forward and falls at the depth as well. These are caused by the
unequal temperature of equator and Polar Regions.
Tides are the rise and fall of seawater occurring twice in a
lunar day.
24) Distinguish between magnitude and intensity of
the earthquake.
Intensity of an earthquake may be
defined as the ratio of an earthquake based on actual effects produced by the
quakes on the earth.
Magnitude
(M) of a tectonic earthquake may be defined as the rating of an earthquake
based on the total mount of energy released when the over strained rocks
suddenly rebound causing the earthquake.
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