This document discusses the three main types of rocks: igneous, sedimentary, and metamorphic. Igneous rocks form from the cooling of magma either below or above the surface. Sedimentary rocks form through the compaction and cementation of sediments. Metamorphic rocks form from existing rocks undergoing changes due to heat, pressure, and chemicals, usually deep within the Earth. The rock cycle illustrates how the three rock types are interrelated as they form and change over time through geological processes.

1. ROCKS
Presented By
MD NURUDDIN
SURVI SONL
B.TECH(BIOTECH)
SHARDA UNIVERSITY

2. What are Rocks?
 A rock is a naturally occurring
solid mixture of one or more
minerals, or organic matter
 Rocks are classified by how they
are formed, their composition, and
texture
 Rocks change over time through
the rock cycle

3. Igneous Rocks
 Igneous rock begins as magma.
 Igneous rock is formed through the cooling
and solidification of magma or lava.
 Magma freezes between
700 °C and 1,250 °C
 Magma is a mixture of
many minerals

4. Extrusive and Intrusive rocks
 At the surface, lava hardens to form extrusive rocks
with tiny crystals or glassy texture.
 Beneath the surface, magma hardens to form intrusive
rocks with easily visible crystal texture.

5. Sedimentary Rocks
Sedimentary rocks form when
sediments harden into rocks
Three Types:
1. Clastic: formed from
fragments of other rocks.
2. Chemical: formed from
mineral grains that come out
of solution.
3. Organic: formed from the
remains of plants/animals.

6. Metamorphic Rock
 Meaning to change shape
Metamorphic rocks
“morph” (change) from
existing rock, due to heat,
pressure and chemicals.
 Usually takes place deep in
the Earth

7. Types of metamorphism
 Regional Metamorphism: large areas of rock are
under intense heat/pressure, which occurs during
mountain-building.
 Contact Metamorphism: when hot magma forces
itself into overlying rock (intrusions) and bakes the
rock

8. Metamorphic Rock
 Foliated - contain aligned grains of flat minerals
Gneiss is foliated
metamorphic rock
that has a banded
appearance and is
made up of granular
mineral s.

9. Metamorphic Rock
 Non-Foliated – mineral grains are not arranged in
plains or bands
Marble is a non-
foliated
metamorphic rock
that is produced
from the
metamorphism of
limestone.

10. THE ROCK CYCLE
The three types of rocks are very closely related:
 Igneous rocks are attacked by erosion and
weathering to form sediments
 Crustal movements can cause deep rocks to
reach high temperatures and to melt back into
magma
 Igneous and sedimentary rocks exposed to
intense heat and pressure can become
metamorphic