Geology

GEOLOGY
Presented by:
K TARUN KUMAR
STRUCTURAL ENGINEERING
INSTITUTE OF AERONAUTCAL ENGINEERING

Definition:-
• The science which deals with the physical structure and
substance of the earth, their history, and the processes which act
on them.
• The geological features of a district.
• The geological features of a planetary body.
Geo
logous
Geology Earth science

The importance of geology in civil engineering may briefly as
follows:
• Geology provides a systematic knowledge of construction
material, its occurrence, composition, durability and other
properties. Example of such construction materials is building
stones, road metal, clay, limestones and laterite.

• The knowledge of the geological work of natural agencies
such as water, wind, ice and earthquakes helps in planning
and carrying out major civil engineering works. For example
the knowledge of erosion, transportation and deposition helps
greatly in solving the expensive problems of river control,
coastal and soil conservation.

• Ground water is the water which occurs in the subsurface
rocks. The knowledge about its quantity and depth of
occurrence is required in connection with water supply,
irrigation, excavation and many other civil engineering works.

• The foundation problems of dams, bridges and buildings are
directly concerned with the geology of the area where they are
to be built. In these works drilling is commonly undertaken to
explore the ground conditions. Geology helps greatly in
interpreting the drilling data.
• In tunneling, constructing roads, canals, docks and in
determining the stability of cuts and slopes, the knowledge
about the nature and structure of rocks is very necessary.
• Before staring a major engineering project at a place, a
detailed geological report which is accompanied by geological
maps and sections, is prepared. Such a report helps in planning
and constructing the projects.

Physical Geology:
• Physical Geology uses the scientific method to explain natural
aspects of the Earth - for example, how mountains form or
why oil resources are concentrated in some rocks and not in
others.
• This chapter briefly explains how and why Earth's surface, and
its interior, are constantly changing. It relates this constant
change to the major geological topics of interaction of the
atmosphere, water and rock.

Petrology:-
• Petrology is the branch of geology that studies the origin,
composition, distribution and structure of rocks.
• (from the Greek language : petra-"rock" and logos- "study")
• “Lithology” was once approximately synonymous
with petrography, but in current usage, lithology focuses on
macroscopic hand-sample or outcrop-scale description of rocks
while petrography is the specialty that deals with microscopic
details.

Branches:
• There are three branches of petrology, corresponding to the
three types of rocks:
Igneous, metamorphic, and sedimentary.
• Igneous petrology focuses on the composition and texture
of igneous rocks (rocks such as granite or basalt which have
crystallized from molten rock or magma). Igneous rocks
include volcanic and plutonic rocks.

• Sedimentary petrology focuses on the composition and texture
of sedimentary rocks (rocks such as sandstone, shale,
or limestone which consist of pieces or particles derived from
other rocks or biological or chemical deposits, and are usually
bound together in a matrix of finer material)

• Metamorphic petrology focuses on the composition and texture
of metamorphic rocks (rocks such as slate, marble, gneiss,
or schist which started out as sedimentary or igneous rocks but
which have undergone chemical, mineralogical or textural
changes due to extremes of pressure, temperature or both).
• Metamorphic rocks arise from the transformation of
existing rock types, in a process called metamorphism, which
means "change in form". The original rock (protolith) is
subjected to heat (temperatures greater than 150 to 200 °C)
causing profound physical and/or chemical change.

Structural geology:
• Structural geology is the study of the three-dimensional
distribution of rock units with respect to
their deformational histories.
• The primary goal of structural geology is to use measurements
of present-day rock geometries to uncover information about the
history of deformation (strain) in the rocks, and ultimately, to
understand the stress field that resulted in the observed strain
and geometries.

Weathering of Rocks:
• Weathering breaks down and loosens the surface minerals of rock so
they can be transported away by agents of erosion such as water, wind
and ice.
• There are two types of weathering: mechanical and chemical.
• Mechanical or physical weathering involves the breakdown of rocks
and soils through direct contact with atmospheric conditions, such as
heat, water, ice and pressure.
• The second classification, chemical weathering involves the direct
effect of atmospheric chemicals or biologically produced chemicals
also known as biological weathering in the breakdown of rocks, soils
and minerals.

Geology

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