5. What is a rock?
We all know what rocks are right? They are lying on the
ground everywhere! They are the mountains, and
canyons that you can’t help but notice. We have all
thrown them, sat on them, and dug them out of our
gardens. However, to pin down an exact definition…
that is something not all of us could do.
A rock is:
A solid Naturally occurring Is made up of minerals or
mineral like matter.
Perhaps the more important question is “why study rocks?”
Rocks are the pages in the history book of the earth. They
tell stories of times long past. From rocks, we have
learned of dinosaurs, trilobites and thousands of other
life forms that existed on earth once but are now no more.
6. We have learned that the earth is constantly
moving, shifting, and changing. Rock is continually being
created. It is heated, squeezed, and weathered into new
rocks.
Rocks are simply aggregates of mineral grains. Each rock
is unique as the composition of a rock varies from
specimen to specimen. Understanding rocks is crucial to
understand the make
up of the earth. Rocks are economically vital, and the
minerals extracted from them are used in every aspect of
our lives.
7. From Wikipedia :
In geology, rock or stone is a naturally occurring
solid aggregate of one or more minerals or mineraloids.
For example, the common rock granite is a combination
of the quartz, feldspar and biotiteminerals. The Earth's
outer solid layer, the lithosphere, is made of rock.
Rocks have been used by mankind throughout history.
From the Stone Age, rocks have been used for tools. The
minerals and metals found in rocks have been essential
to human civilization.
So I think this enough for the rocks now lets move on to
the rock cycle
8.
9.
10. ROCK CYCLE:
The rock cycle is a basic concept in geology that
describes the time-consuming transitions through
geologic time among the three main rock types:
sedimentary, metamorphic, and igneous.
As the diagram illustrates each of the types of
rocks is altered or destroyed when it is forced out
of it equilibrium conditions.
An igneous rock such as basalt may break down
and dissolve when exposed to the atmosphere , or
melt as it is subducted under a continent. Due to
the driving forces of the rock cycle, plate tectonics
and the water cycle, rocks do not remain in
equilibrium and are forced to change as they
encounter new environments.
11. The rock cycle is an illustration that explains how
the three rock types are related to each other, and
how processes change from one type to another
over time.
Most rocks on earth began as igneous rocks. Let's
trace a possible rock cycle for newly formed
igneous rocks.
Igneous rocks are formed from magma. Magma
cools and solidifies into rock.
When igneous rocks are exposed on the surface,
time and weather break the rock down into
smaller and smaller pieces. This process is called
‘Weathering and Erosion’.
12. Wind and water carry the smaller pieces of
igneous rocks into piles called sediment beds.
Over time the sediment beds get buried and the
pieces of rock become cemented together to form
a new type of rock called a ‘Sedimentary rock’.
If our sedimentary rock is exposed at the
surface, it can be eroded away and eventually
changed into new sedimentary rock. However, if
our sedimentary rock gets buried deep in the
Earth, heat and pressure essentially bake the
rock, changing it into something new. This
process is called metamorphosis, and the new
rock is called a metamorphic rock.
Metamorphosis can happen to igneous rocks as
well.
13. Metamorphic rocks can also be weathered and
eroded and eventually changed into sedimentary
rocks. Or, if metamorphic rock is forced deeper
into the Earth, the rock can melt and become
magma.
If the magma cools and hardens it will form into
igneous rock. Igneous rocks and sedimentary
rocks can also be forced deep into the earth and
melt into magma. Once magma cools it forms
igneous rocks.
o Now lets see a video so you can imagine what
was the slide is trying to tell you (video)
14. METMORPHISM, METAMORPHIC ROCK
AND THEIR TYPES
Metamorphic rocks arise from the
transformation of existing rock types, in a
process called metamorphism, which means
"change in form“
The word "Metamorphism" comes from the
Greek: meta = change, morph = form, so
metamorphism means to change form. In
geology this refers to the changes in mineral
assemblage and texture that result from
subjecting a rock to conditions such pressures,
temperatures, and chemical environments
different from those under which the rock
originally formed.
15. What are Metamorphic Rocks?
Metamorphic rocks have been modified by heat,
pressure, and chemical processes, usually while
buried deep below Earth's surface. Exposure to
these extreme conditions has altered the
mineralogy, texture, and chemical composition
of the rocks.
OR
Metamorphic rocks form deep within the Earth
when heat and pressure are applied to either
igneous rocks or sedimentary rocks. This heat
and pressure in essence cooks the rocks,
changing their structure substantially.
16. Metamorphic rocks are one of the three main
types of rocks and are the most common of rock
on the continental plates. Fossils may be found
in metamorphic rocks, but only if the
metamorphic rock was formed from a
sedimentary rock that already had the fossil in it.
However, the fossil is most likely going to be
crushed, warped, or somehow changed because
the process that changes sedimentary rock into
metamorphic rock will change the fossil, too.
17. TYPES OF METAMORPHIC ROCK
There are two basic types of metamorphic rocks.
(1) Foliated metamorphic rock
such as gneiss, phyllite, schist, and slate have a
layered or banded appearance that is produced
by exposure to heat and directed pressure.
(2) Non-foliated metamorphic rocks
such as hornfels,marble, quartzite, and novaculite
do not have a layered or banded appearance.
