2. Introduction: Petrology deals with the study of rocks
Petro = rock , ( litho=rock )
Logos = study
Petrology comprises the
Origin,
Association
Occurrence
Mineral composition
Texture
Structure
Physical properties etc.. of rocks
3. Rock: Aggregated solids of minerals is called rock.
(Or)
A rock may be defined as “an unit of the earth’s crust
All rocks are made of two or more minerals, but minerals are not made of
rocks.
4. Geological Classification of Rocks
• There are three main types of rocks:
1.1. IgneousIgneous - formed when molten rock
cools.
2.2. MetamorphicMetamorphic – rocks changed by the
effect of heat and pressure.
3.3. SedimentarySedimentary – formed by the
consolidation of sediments in the
layered or bedded rocks deposited in
the ocean bottom or huge lakes, etc.
5. What type of rock is formed
when magma cools and hardens?
Characteristics
A tough, frozen melt with little texture or layering;
mostly black, white and/or gray minerals; may look like
granite or like lava
6. What type of rock is formed
when change occurs from heat
and pressure in the Earth?
Characteristics
Hardened sediment with layers (strata) of sandy or
clayey stone; mostly brown to gray; may have
fossils and water or wind marks
7. What type of rock is formed when
weathering and erosion cause
sediments to press together in
layers?
Characteristics
Tough rock with layers (foliation) of light and dark
minerals, often curved; various colors; often glittery
from mica
9. Rock Cycle
• The three different types of
rocks--- igneous, sedimentary
and metamorphic---are
constantly being changed from
one type to another type
through various geological
processes.
24. • The rock cycle demonstrates the
relationships among the three
major rock groups
• It is powered by the interior heat of
the Earth
• As well as earth’s momentum
and…
• The energy from the sun
• It involves processes on the
Earth’s surface as well as the
Earth’s interior
• It connects the “hydrologic cycle”
with the “tectonic cycle”.
In Conclusion…
32. Civil Engineering importance of Petrology
• Petrology provides a proper concept and logical basis
for interpreting physical properties of rocks.
• The study of texture, structure, mineral composition,
chemical composition etc., gives all necessary details
regarding the strength,durabiliy,colour,appeareance,
workability, etc.,
These inherent characters of rocks are of chief concern for a
civil engineer to judiciously assess the suitability occurring at
project site for required purpose
