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Geology27th June 2008
VENKAT M.
QA-Minex
GEOLOGY
GEO – Earth
LOGUS – Speech/Study
Geology – Study of earth
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James Hutton, the Scottish geologist, naturalist, chemist
and experimental farmer, is the father of modern geology.
The Crust The thin skin of Earth - 3 to 40 miles
thick.
The Mantle This deep layer of warm rock accounts
for two-thirds of the mass of our planet.
The Outer Core Made of molten iron, nickel, and
Earth
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The Outer Core Made of molten iron, nickel, and
other ingredients yet to be determined. Streaming
at possibly one to several miles per week.
The Inner Core a ball of iron alloy one-third the
size of the moon in the center of earth. This metal
ball is broiling hot at 11,000 degrees Fahrenheit,
comparable to the surface of the sun, but it
remains solid because of the enormous weight of
all the rest of Earth bearing down on it.
Earth - Magnet
The rotational forces of the liquid
iron are reasonable for the earths
magnetism.
So, there is true and magnetic
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So, there is true and magnetic
north due to the tilt in the axis of
rotation of the earth.
The angle between true and
magnetic north is called
Declination.
• The Earth's surface is made up of a
series of large plates (like pieces of a
giant jigsaw puzzle).
• These plates are in constant motion
travelling at a few centimeters per
year.
Plate Tectonics
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year.
• Convection currents beneath the
plates move the plates in different
directions.
• The source of heat driving the
convection currents is radioactive
decay which is happening deep in
the Earth.
Plate Tectonics A Small Video
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• The geological time scale is used by
geologists and other scientists to
describe the timing and relationships
between events that have occurred
during the history of Earth.
Geological
Time Scale
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• The vast expanse of geological time
has been separated into eras,
periods, and epochs.
• Younger formations are on top and
as we go down in GTS we will get the
older formations and between each
formation there is a unconfirmity.
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• Naturally occurring
• Solid crystalline substance
• Generally inorganic
Mineral
A Founded in nature, not synthetic.
Composed of atoms arranged in
an orderly, repeating, 3-D array.
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• Generally inorganic
• With a specific chemical
composition.
Formed independently of
plants and animals (organic
material - carbon).
Unique combination and arrangement of
atoms: can be represented with a chemical
formula.
Minerals
Examples: Gold, iron, copper, salt, diamonds,
feldspar, calcium, phosphorus, etc.
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IronFeldspar Gold
MoreMore thanthan oneone kindkind ofof
mineralmineral stuckstuck togethertogether
Rocks
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mineralmineral stuckstuck togethertogether
formsforms aa ROCKROCK..
Rocks - Types
Igneous
Sedimentary
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Sedimentary
Metamorphic
Rocks - IGNEOUS
• Deep inside the Earth, rocks and minerals melt under tremendous
heat. This forms magma.
• When the magma cools back down, it hardens and forms new
rocks. These rocks are called IGNEOUS rocks.
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Rocks - IGNEOUS
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EXTRUSIVE
Forms when lava cools quickly on the Earths
surface
Forms from molten rock
cooling and solidifying
INTRUSIVE
Magma cools slowly over millions of years deep beneath the surface –results in Crystalline
formations
Rocks - IGNEOUS
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Rocks - IGNEOUSThese BASALT columns near Fingal’s
Cave form the base of the Scottish
island of Staffa. The columns formed
when cooling lava flows met bedrock
and the region’s cold weather.
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Rocks - IGNEOUS
Mount Rushmore - Keystone, South Dakota
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Rocks - IGNEOUS
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BASALT – Extrusive igneous rock GRANITE – Intrusive igneous rock
Rocks - SEDIMENTARY
Weathering and Erosion
Transportation Deposition
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Compaction and Cementation
Sedimentary Rock
Rocks - SEDIMENTARY
Sedimentary rocks are divided into two categories
Chemical
Mineral are dissolved in to the water…water is evaporated off and leaves behind chemical
Clastic
Made from eroded fragments of other rocks
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evaporated off and leaves behind chemical sedimentary rocks
Examples - Limestone & Gypsum
fragments of other rocks
Shale
Sandstone
Conglomerate
Rocks - SEDIMENTARY
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Sandstone Limestone Shale Conglomerate
Rocks - SEDIMENTARYBryce Canyon, Utah.
The sea dried up, the sandstone was uplifted to form a vast plateau.The Paria River eroded the layers to form the spectacular scenery.
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Rocks - SEDIMENTARY
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Rocks - SEDIMENTARY
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Hatshepsut Temple, Luxor, Egypt.
This Temple was carved directly from the limestone cliff walls.
Rocks - METAMORPHIC
• When rocks are subjected to
greater heat and pressure inside
the Earth, they are changed into
rocks which are different from the
original.
Meta – Change , Morphos - Shape , Metamorphic – Change in shape or form
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• This change occurs while the
original rocks are still in a solid
state.
• Thus the new rocks formed are
called metamorphic rocks.
Rocks - METAMORPHIC
Two types of metamorphism
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Contact
Rock surrounding a magma body get
cooked and changes due
Regional
Tectonic forcesMetamorphism
occurs over a large area
Rocks - METAMORPHIC
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Rocks - METAMORPHIC
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Rocks - METAMORPHICParent Rock Metamorphic Rock
Granite Gneiss
Shale Slate
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Sandstone Quartzite
Rocks - METAMORPHIC
Michelangelo's Pieta
• Made of marble resulted from
the metamorphism by heat of
limestone or dolomite.
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• Usually whitish but can be
found in other colours due to
impurities.
Rocks - METAMORPHIC
Mt Arapiles, Australia isa world famous rockclimbing site.
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Mountain is quartzite.
Rocks - METAMORPHICTAJ MAHAL
Finished in 1648 with Red sandstone base.Marble walls inlaid with semiprecious gems.
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Rock
Cycle
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Cycle
CoalCoal isis formedformed byby thethe decompositiondecomposition ofof
organicorganic (vegetable)(vegetable) mattermatter underunder highhigh
pressurepressure andand heatheat.. ItIt isis neitherneither MineralMineral
nornor RockRock butbut it’sit’s aa fossilfossil fuelfuel..
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Coal – Stages of
Formation
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PEAT LIGNITE BITUMINOUS ANTHRACITE
Geological
Map of INDIA
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Map of INDIA
Strike - Dip
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• Strike – A horizontal line used to represent the orientation/direction/trend
of the beds.
• Dip – It is the angle from horizontal in which the beds are lying.
Fault & Fold
• Fault (def)- a break in a body of rock along
which some displacement has occurred.
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• Fold (def)- a bend in a body of rock, which is
generally being squeezed.
Fault & Fold - Mechanism
F
O
L
D
F
A
U
L
T
Fault – Normal Fault
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• Normal Faults are produced by tensional forces.
• The upper block (Hanging wall) moves down to the lower
block (Foot wall).
Fault – Reverse Fault
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• Reverse Faults are produced by Compressive forces.
• The upper block (Hanging wall) moves up relative to the lower
block (Foot wall).
Fault – Strike Fault
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• Strike Faults are produced by shearing forces.
• The movement of the blocks is along strike direction.
Fault –Strike Fault
San Andreas Fault, California
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Fold – Terminology
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Fold – Anticline
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Anticlines are folds where the originally horizontal strata has been folded
upward, and the two limbs of the fold dip away from the hinge of the fold
Fold –Syncline
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• Synclines are folds where the originally horizontal strata have been folded
downward, and the two limbs of the fold dip inward toward the hinge of the fold.
• Synclines and anticlines usually occur together such that the limb of a syncline is
also the limb of an anticline.
Folds
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Few more Geological Terms…
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Few more Geological Terms…
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Bedrock - The general term referring to the rock
underlying other unconsolidated material, i.e. soil.
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Sills and dykes are formed when magma intrudes into rock. Sills form where magma
intrudes between layers, they run parallel to the layer. Dykes form when magma intrudes
into a rock along lines of weakness such as fractures and fissures. Dykes cut beds and
range in size from a few cm to several km.
OutcropOutcrop –– AnyAny placeplace wherewhere bedrock/seambedrock/seam isis visiblevisible onon thethe
surfacesurface ofof thethe earthearth..
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Intrusion – A sudden
appearance of different
rock in the middle of
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rock in the middle of
other rock formation.
Questions…
Please
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Please
Finally…
VENKAT M.
QA-Minex