Conservation of Natural Resources Module-3.pptx

GEOLOGY
Geology is the science of the earth
GEO=Earth, LOGY=Study of science
• It deal with the study of Origin , age, interior structure,
and history of earth
• Evolution and modification of various surface features
like rivers, mountains and Lakes.
• Material make ups the earth.

Application of Earth Science in Civil Engineering
Practices
 Mapping
 Exploration
 Project Planning
 Surface water
 Groundwater
 Geological Structures
 Tunneling
 Earthquake

Main and Allied Branch
of Geology
Main Branch Allied Branch
Physical Geology Engineering Geology
Mineralogy Mining Geology
Petrology Geophysics
Structural Geology Geohydrology
Historical Geology Geochemistry
Palaeontology
Economic Geology

Mineralogy
This deals with the study of minerals.
Mineralogy deals with the detailed mode of formation,
composition, occurrence, types, association properties uses
etc .

Mineralogy
Civil Engineering point of view
The strength and durability of the material depends on
chemical composition. The quartzite and marble resemble
one another in shine colour and appearance but quartzite by
virtue of its mineral composition is very hard tough, strong
and durable while the marble disintegrates and
decomposition in a short period because of its mineral
composition and properties.

Petrology
Petro =Rock, Logos =Study.
Petrology deals with study of Rocks .
 The earth crust is also called as lithosphere, is made of
types of rocks. Petrology deals with the
structure, texture, composition, occurrence,
different
formation,
types etc.

Petrology
Civil Engineering point of view
The composition and texture characteristics of rocks
primarily contribute to their strength and durability.
Rocks based on their suitability can be used for foundation
for dams, tunnelling's and other construction materials.
Hence it is most important branch of Geology from civil
Engineering point of view.

Mineralogy
 Minerals have been defined as naturally occurring
substances, mostly inorganic, that are
characterized by a definite chemical composition
and a definite atomic structure .
 The branch of geology dealing with the study of
minerals is designated as Mineralogy.
 Each mineral is generally characterized with a set of
qualities some of which are always distinctive and
differentiate it from other minerals.
 Some of these qualities or properties may be studied
from the body of the minerals, its shape, color, shine,
hardness etc.; these are termed physical properties.

Properties of Minerals
HABIT
 A mineral may sometimes show a definite and
characteristic arrangement in its outer appearance or
physical shape. This shape is expressed by the term
Habit and is typical in the case of many minerals.
 Fibrous habit: -When the mineral is made up of
fibers, generally separable, e.g. in Asbestos.
 Columnar habit: - When the mineral is composed
of thin or thick columns, sometimes flattened, e.g. in
Hornblende. (Apatite)

Bladed habit: - The minerals appears as if composed of
thin, blade like structure, e.g. in Kyanite

Granular habit: - The mineral shows numerous grains
packed together, e.g. in Chromite

Tabular habit: - The mineral is flat that are elongated
e.g. in Calcite, Orthoclase.

 COLOUR
Minerals show great variety of colors. The color of a
substance and its appearance in light depends upon
the composition and structure of the substance

The streak of a mineral is the color of the powder
produced when it is dragged across an un-weathered
surface. ... The surface across which the mineral is
dragged is called a "streak plate", and is generally
made of unglazed porcelain tile.

Conservation of Natural Resources Module-3.pptx

 LUSTER
The Shining / Reflection
of light from the surface
of mineral. The luster of
minerals varies with the
nature of their surface
smooth / rough and the
quantity of light
reflected. The luster of
mineral can be divided
into two groups.
i)Metallic. ii)Non-metallic

 DIAPHENEITY:
Diaphaneity is the ability of the mineral to transmit light
through it. The following terms are used to describe
the varying degree of transmission of light.

 FRACTURE:
The fracture is the nature of the broken surface of
mineral. The breakage of a mineral in a direction other
than that of cleavages. Fracture is described according
to the breakage pattern, i.e. the appearance of the
broken surface.
Note: Cleavage refers to the way some minerals break
along certain lines of weakness in their structure

 Even fracture-Appearance of a mineral in its broken
surface is Smooth. Mineral examples: Chert, Mica.
 Uneven fracture- when the mineral breaks with very
rough and coarse surfaces. Mineral examples:
Chromite and various other minerals.
 Conchoidal fracture- when a mineral breaks with
curved Surfaces or concentric Rings or half moon
shape. Mineral example: Quartz

Hardness
The hardness of a mineral is the resistance it offers to
abrasion, which is determined by observing the
comparative ease or difficulty in scratching it with
another mineral of known hardness. It is always
expressed by Moh's Scale of Hardness

 Specific gravity is the "heaviness" of a mineral. It is
defined as a number that expresses the ratio between
the weight of a mineral and the weight of an equal
volume of water.
 A mineral possessing heavier and closely spaced atoms
will have a high specific gravity: whereas, a mineral
possessing lighter and widely-spaced atoms will have a
low specific gravity
 All minerals have been found to possess a specific
gravity varying between 1 to 20: but most of them do
have specific gravities varying between 2 to 7.

DESCRIPTION OF MINERALS:
1. Quartz Group
 Form - Granular
 Colour - (varieties of quartz) Streak - Colourless
 Luster - Vitreous Cleavage – Absent
 Fracture – Conchoidal to uneven Hardness – 7 [High]
 Sp. gr. – Low to Medium. C C - Si 02

Occurrence– widely distributed all over India occurs
Beach Sand, River sand.
Uses:
(1) Manufacture of glass, porcelain
(2) Flux in metallurgical operation
(3) Agates are used as Ornaments
(4) Pure quartz crystal shows piezoelectricity
(5) Quartz plates are used in controlling frequencies in
radio circuits, radar, ultrasonic and multiple telephone
lines.
(6) Quartz is used in refractories
(7) Pure silica is used in ceramics
(8) Pure sand, free from impurities is used in
manufacturing Sand paper and Abrasive cloth

orthoclase Plagioclase
Microcline

Types of weathering
 Physical Weathering
 Chemical Weathering
 Biological Weathering
Physical weathering, also known as mechanical
weathering or disaggregation, is the process class that
causes rocks to disintegrate without chemical change.
Abrasion (the process by which clasts and other particles
are reduced in size) is the primary process in physical
weathering.
 Due to temperature, pressure, frost etc., physical weather
may occur. For instance, cracks exploited by physical
weathering will increase the surface area that is exposed
to chemical action, thereby increasing the rate of
disintegration.

Where does Physical Weathering occur?
 In places where there is little soil and few plants grow,
such as mountain regions and hot deserts, physical
weathering occurs especially.
How does Physical Weathering occur?
 Either by repeated melting and freezing of water
(mountains) or by expanding and shrinking the
surface layer of rocks baked by the sun (hot deserts).

Chemical Weathering
 Chemical weathering changes rock composition,
often transforming them into different chemical
reactions when water interacts with minerals.
 Chemical weathering is a gradual and ongoing
process as the rock mineralogy adjusts to the
environment near the surface.
 The rock’s original minerals develop new or
secondary minerals. The oxidation and hydrolysis
processes are most important in this.
 Chemical weathering is enhanced by geological
agents such as water and oxygen, as well as
biological agents such as microbial and plant-root
metabolism acids.

Where does Chemical Weathering occur?
 These chemical processes require water and occur
faster at higher temperatures, so it is best to have
warm, humid climates. The first stage in soil
production is chemical weathering (especially
hydrolysis and oxidation).

How does Chemical Weathering occur?
 There are various types of chemical weathering, the
most important of which is:
 Solution
 Removal of rock by acidic rainwater in solution. In
particular, dissolved CO2-containing rainwater (this
process is sometimes referred to as carbonation)
weathers calestone.
 Hydrolysis
 Acidic water breakdown of rock producing clay and
soluble salts.
 Oxidation
 Rock breakdown by oxygen and water, often giving a
rusty – colored weathered surface to iron – rich rocks.

Biological Weathering
 Biological weathering is the weakening and
subsequent breakdown by plants, animals and
microbes of rock.
 Growing roots of plants can put stress or pressure on
rock. Even though the process is physical, a biological
process (i.e. growing roots) exerts the pressure.
 Biological processes can also produce chemical
weathering, such as when organic acids are produced
by plant roots or microorganisms that help dissolve
minerals.

 Microbial activity breaks down rock minerals by altering
the chemical composition of the rock, making it more
weather sensitive.
 One example of microbial activity is lichen ; lichen is a
symbiotic relationship between fungi and algae. Fungi
release chemical substances that break down rock minerals
; the algae consume the minerals thus released from rock.
 Holes and gaps continue to develop on the rock as this
process continues, exposing the rock to physical and
chemical weathering.
 Burrowing animals can move fragments of rock to the
surface, exposing the rock to more intense chemical,
physical, and biological processes, thereby indirectly
enhancing the weathering process.

Fig: Effects of Weathering on
Rocks

Landforms
 A landform is a natural or artificial feature of the
solid surface of the Earth .
 Landforms together make up a given terrain , and their
arrangement in the landscape is known as topography
 Typical landforms include hills, mountains, valleys as
well as shoreline features such as bays and seas
including submerged features like volcanoes and
ocean basins .

Physical characteristics
 Landforms are categorized by characteristic physical
attributes such as elevation, slope,
orientation, stratification, rock exposure, and soil
type.
 Gross physical features or landforms include intuitive
elements such as hills, valleys, river, volcanoes and
numerous other structural and size-scaled (ex. Ponds
vs. lakes, hills vs. mountain) elements including
various kinds of inland and oceanic water bodies and
sub-surface features

Conservation of Natural Resources Module-3.pptx

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