The document provides an overview of geology, describing the structure of the Earth and key concepts in the field. It begins with definitions of geology and discusses the four spheres that make up the Earth: the geosphere, hydrosphere, atmosphere, and biosphere. Key points about the layers of the Earth's interior and crust are summarized. The remainder of the document outlines principles of geology including plate tectonics, geological timescales, dating methods like radioactive decay, and the progression of life forms through different eras.

1. Geology

2. DEFINITION
GEOLOGY
Greek Earth
The study of
Geology = The study of Earth

3. The Earth’s Four
Spheres

4. The Geospher e
The solid earth, consisting of
the entire planet from the center
of the core to the outer crust.

5. Geosphere

6. INNER CORE
- HOT!!!! –
Thought to be as
hot as the surface
of the Sun!
- Solid
- Composed of Iron
and Nickel

7. OUTER CORE
• HOT!
(but not as hot as
the inner core)
• Liquid
• Composed of Iron
and Nickel

8. MANTLE
• Still hot! – but
not as hot as the
core!
• Largest layer
• Composed of
various materials
• Solid and liquid

9. CRUST
• Cool
• Where we live on
• Composed of
rocks, various
materials make up
the crust
• Solid or Liquid?

10. Even though 70% of
the Earth’s surface is
water, there is crust
under the water. The
water sits on top of the
crust!

11. Lithosphere
The cool, rigid outer part of Earth, about 100
kilometers thick, which includes the crust and the
upper most mantle.
According to the theory develop in 1960s, the
lithosphere is broken down into seven major
segments called TECTONIC PLATES. These
tectonic plates float on the weak, plastic, mantle
rock , called ASTHENOSPHERE beneath, and glide
across earth.

12. -The Earth’s crust moves!!!!!
-The continents have not always been arranged
like they are today.
- The
Earth’s
crust is
divided into
segments
called
plates.

13. Pangaea
• Supercontinent that existed 250 million
years ago
• All the land made up 1 continent until its
split into the modern day configuration of
the continents.
• Discovered by Alfred
Wegner in 1912, but
not accepted by the
public until after his
death in the 1950’s.

16. The Hydrosphere
Includes all of earth’s water, which
circulates among oceans, continents, glaciers
and the atmosphere.
Earth’s Water Percentage
Oceans 97.5 %
Glaciers 1.8 %
Groundwater 0.63 %
Streams and lakes 0.01 %
Atmosphere 0.001 %

18. OCEANS cover 71 % of earth and contain 97.5 % of its
water.
Ocean currents transport heat across vast distances, altering
global climate.
GLACIERS cover 10 % earth’s land surface and about 1.8
% of earth’s water.
Only 0.64 % of Earth’s total water exists on the continents
as liquid. Although it is a small proportion
FRESHWATER is essential to life on earth.
Lakes , rivers, water and streams are the most visible
reservoirs of continental water but they constitute only 0.01
% of earth’s water.

19. GROUNDWATER which saturates rock and soil of the
upper few kilometers of the geosphere is much more
abundant and accounts for 0.63 % of Earth’s water.
Water located in the gaps and pores in rocks below
earth’s surface.
Water gets there because the soil in places is
permeable which means water can easily pass through.
It can collect in large underground lakes called
aquifers.
Wells can be dug to access groundwater.
Only a miniscule amount, 0.001 % , EXISTS IN THE
ATMOSPHERE, but because this water is so mobile , it
profoundly affects both weather and climate of the planet.

20. The total amount of water on the
Earth remains fairly constant.
The water moves above, across,
and through Earth’s crust and
ecosystems.

21. The Water Cycle

22. The Sun
• Heat energy from the sun drives the
water cycle.
• Heat reaches the Earth by radiation.

23. Evaporation
• The process of liquid water
changing into water vapor.
• Oceans contribute about 80% of
all the water vapor in the air.

24. Transpiration
• The process by which plants release water
vapor into the air through their leaves

25. Condensation
• The process in which water vapor changes
into liquid water as the water vapor rises
into the air and cools.
• When water vapor condenses on particles in
the air and tiny water droplets or ice
crystals form, a cloud is visible.

26. Precipitation
• Solid or liquid water that falls from the air to Earth
• Rain, snow, sleet, and hail are forms of
precipitation.
• Form when drops of condensation in clouds come
together and grow too large to remain suspended
• Precipitation always “runs” downward due to
gravity

27. All precipitation starts as snow!
• Snow falls into warm air and melts = rain
• Snow falls into cold air and never melts on
the way down=snow
• Snow falls, melts, and refreezes as it travels
through cold air=sleet
• Snow falls, melts, refreezes and becomes
the “seed” kept suspended by updrafts until
it gets too heavy and falls=hail

28. Where does precipitation go?
• Most falls back into the ocean
• Some falls on the ground and soaks in
• Some falls on the ground and runs off the
surface into tributaries (streams and small
rivers that feed into a main river)

29. The Atmosphere
Mixture of gases, mostly nitrogen and oxygen, with
smaller amounts of Argon, CO2 and other gases.
Held to earth by gravity and thins rapidly with
altitude.
Ninety nine percent is concentrated in the first 30
kilometers , but a few traces remain as far as 10,000
km above earth’s surface.

30. The
TBhei zoosnep ohf eearrthe comprising all
forms of life in the sea , on land and
in the air.

31. Geologic Time:
A story in the rocks

32. IT IS ESTIMATED THAT THE EARTH FORMED
ALONG WITH THE SOLAR SYSTEM 4.6 BILLION
YEARS AGO (4,600 MYA)
GEOLOGIC TIME SCALE
A SUMMARY OF THE MAJOR EVENTS IN EARTH’S HISTORY
EON – largest segment of geologic time
ERA
PERIOD
EPOCH – smallest segment of geologic time

34. RELATIVE TIME VS. ABSOLUTE TIME
PLACES EVENTS IN A
SEQUENCE BUT DOES
NOT IDENTIFY THEIR
ACTUAL DATE OF
OCCURRENCE
IDENTIFIES THE ACTUAL
DATES OF GEOLOGIC
EVENTS
EXAMPLE
A LIST IN
CHRONOLOGICAL
ORDER OF WHAT YOU
HAVE DONE TODAY UP
UNTIL THIS TIME
THE EXACT TIMES AT
WHICH YOU DID
THESE THINGS

36. Principle ooff OOrriiggiinnaall
HHoorriizzoonnttaalliittyy • The pprriinncciippllee ooff oorriiggiinnaall hhoorriizzoonnttaalliittyy
states that sediments are deposited in
horizontal layers that are parallel to the
surface on which they were deposited.
• This implies that tilted or folded layers
indicate that the crust has been
deformed.

37. LAW OF SUPERPOSITION- IN UNDISTURBED
SEDIMENTARY ROCKS THE OLDEST ROCK
LAYERS ARE AT THE BOTTOM AND THE
YOUNGEST ARE AT THE TOP.

38. LAW OF CROSS-CUTTING
RELATIONSHIPS-The
obvious principle that a rock
or feature must first exist before
anything can happen to it.

39. IIggnneeoouuss IInnttrruussiioonnss aanndd EExxttrruussiioonnss
When magma forces its way into cracks or
crevices in crustal rock and solidifies, it forms a
mass of igneous rock called an iinnttrruussiioonn.

40. When lava solidifies at the surface it forms a mass of igneous
rock called an eexxttrruussiioonn.
Since the rroocckk tthhaatt the magma moved through, or over, eexxiisstteedd
pprriioorr to the intrusion, (or extrusion), it mmuusstt bbee oollddeerr.

41. Evolution
The biological theory
that life forms have
changed in their physical
and genetic characteristics
overtime.

42. The Principle of Faunal
Succession
States that species succeeded
one another through time in a
definite and recognizable order
and that the relative ages of
sedimentary rocks can therefore
be recognized from their fossils.

43. Unconformity
An interruption in sediment deposits or
a break between eroded igneous and
overlying sedimentary layers, causing a gap
in the geological record for that place.

44. UNCONFORMITY- A PLACE IN THE ROCK RECORD WHERE
LAYERS OF ROCK ARE MISSING BECAUSE OF UPLIFT AND
EROSION. THE RESULT CAN BE A LARGE AGE
DIFFERENCE BETWEEN THE ROCKS ABOVE AND THOSE
BELOW THE EROSIONAL SURFACE (IT APPEARS LIKE A
SQUIGGLY LINE IN A CROSS-SECTION)

45. MATCHING OF ROCK
LAYERS THAT CAN BE
SEEN AT THE EARTH’S
SURFACE, OVER A LARGE
AREA
A KEY BED IS A THIN, WIDESPREAD LAYER, USUALLY OF
VOLCANIC ASH, THAT CAN BE USED TO CORRELATE AN
EXACT POINT OF TIME

47. • BBeeddrroocckk is the solid, unbroken rock of the
crust.
• An oouuttccrroopp is bedrock that is exposed at
the Earth’s surface.
–OOuuttccrrooppss provide opportunity for
geologists to directly study the layers of
the bedrock, tracing them from one
location to another – called ““wwaallkkiinngg aann
oouuttccrroopp””..

48. A FOSSIL IS ANY EVIDENCE OF EARLIER LIFE
PRESERVED IN THE ROCK
ORIGINAL REMAINS (RARE) – THE ACTUAL
UNCHANGED REMAINS OF THE PLANT OR
ANIMAL ARE PRESERVED.
REPLACED REMAINS – THE SOFT PARTS OF THE
ORIGINAL ANIMAL HAVE DISAPPEARED AND THE
HARD PARTS HAVE BEEN REPLACED BY MINERAL
MATERIAL. (PETRIFIED WOOD)

49. MOLDS AND CASTS – FOSSIL SHELLS OR BONES ARE
DISSOLVED COMPLETELY OUT OF THE ROCK LEAVING
A HOLLOW DEPRESSION IN THE ROCK. NEW MINERAL
MATERIAL FILLS THE MOLD IT FORMS A CAST OF THE
ORIGINAL FOSSIL.
TRACE FOSSILS – EVIDENCE OF
LIFE OTHER THEN REMAINS,
WHICH INCLUDES ANY
IMPRESSIONS LEFT IN THE ROCK.
(TRAILS, FOOTPRINTS, TRACKS,
BURROWS)

50. • IInnddeexx ffoossssiillss are fossils or organisms
that lived over an extensive area,
preferably over the entire Earth, for
relatively short periods of time.
• IInnddeexx ffoossssiillss are useful in correlating
the sedimentary rocks in which they
are found.

51. INDEX FOSSIL

52. INDEX FOSSILS

53. FFoossssiill CCoorrrreellaattiioonn

54. VVoollccaanniicc TTiimmee MMaarrkkeerrss
• Severe volcanic eruptions can deposit a
thin layer of vvoollccaanniicc aasshh over the surface
of the entire Earth.
• These layers within a rock sequence may
remain distinguishable and pprroovviiddee aa ttiimmee
mmaarrkkeerr. (Similar to index fossils)

55. MEASURING ABSOLUTE TIME
TREE RINGS
EACH RING REPRESENTS A SINGLE
YEAR (SPRING/FALL) THE WIDTH OF
THE RING DEPENDS UPON THE
TEMPERATURE AND RAINFALL
VARVES
GLACIAL LAKE DEPOSITS. A THICK
LIGHT COLORED LAYER IN THE
SUMMER AND A THIN DARK LAYER
IN THE WINTER

56. RADIOACTIVE DATING
USED TO DATE FAR BACK IN TIME. CERTAIN ROCKS
CONTAIN RADIOACTIVE ISOTOPES
RADIOACTIVE ISOTOPES ARE ATOMS OF
ELEMENTS THAT GIVE OFF RADIATION FROM
THEIR NUCLEI
RADIOACTIVE DECAY IS THE PROCESS BY
WHICH A RADIOACTIVE ISOTOPE CHANGES
INTO A NEW STABLE ELEMENT

57. THE RATE AT WHICH A RADIOACTIVE ELEMENT DECAYS.
IT IS THE TIME IT TAKES FOR HALF OF THE ATOMS OF THE
RADIOACTIVE ELEMENT TO DECAY TO A STABLE END
PRODUCT (SEE PAGE 1 OF THE ESRT)
AT THE END OF EACH HALF-LIFE, HALF OF THE
RADIOACTIVE MATERIAL REMAINS
PARENT ISOTOPE = THE RADIOACTIVE ISOTOPE THAT BEGINS
DAUGHTER ISOTOPE = THE STABLE ISOTOPE THAT HAS BEEN CHANGED

58. RADIOCARBON DATING USES THE RADIOACTIVE
ISOTOPE CARBON-14 FOUND IN ALL LIVING THINGS.
BECAUSE CARBON-14 IS CONTINUALLY ABSORBED BY FOOD
AND WATER IT STAYS CONSTANT IN LIVING THINGS.
WHEN THE LIVING THING DIES THE PERCENTAGE OF
CARBON-14 DECREASES AT THE RATE OF ITS HALF-LIFE.
CAN BE USED TO DATE BACK ABOUT 100,000 YEARS

59. URANIUM LEAD METHOD IS USEFUL TO DATE ROCKS
OLDER THAN 10 MILLION YEARS. CAN BE USED ONLY ON
IGNEOUS ROCKS THAT CONTAIN THE RIGHT KIND OF
URANIUM
RUBIDIUM-STRONTIUM METHOD CAN ALSO BE USED
TO DATE OLDER ROCKS BECAUSE OF ITS LONG HALF-LIFE.
IT IS ALSO VERY COMMONLY FOUND IN IGNEOUS ROCKS.
POTASSIUM-ARGON METHOD IS VERY USEFUL SINCE
POTASSIUM-40 CAN BE FOUND IN METAMORPHIC,
SEDIMENTARY, AND IGNEOUS ROCKS. IT CAN DATE OLDER
ROCKS BUT MAY ALSO DATE ROCKS AS YOUNG AS 50,000
YEARS

60. GGeeoollooggiicc TTiimmee SSccaallee
• Geologic time is subdivided divided into units
based on fossil evidence.
• There are 4 major divisions:
– PPrreeccaammbbrriiaann – represents the first 85% of Earth’s
history (mostly devoid of fossils).
– PPaalleeoozzooiicc EErraa – represents ~ 8.5% of Earth’s history
(invertebrates, fishes, amphibians, vertebrates and
land plants first appear).
– MMeessoozzooiicc EErraa – rep. ~ 3.5% of Earth’s history
(dinosaurs, earliest birds, and mammals).
– CCeennoozzooiicc EErraa – rep. ~ 1.4% of Earth’s history
(humanoids show up late ~0.04% of history).

63. What is the Earth’s time scale?
• The Geological time scale is a record of the
life forms and geological events in Earth’s
history.
• Scientists developed the time scale by
studying rock layers and fossils world wide.
• Radioactive dating helped determine the
absolute divisions in the time scale.

65. Divisions of Geologic Time
• Eras are subdivided into periods...periods are
subdivided into epochs.
Era
Period
Epoch
E + P = EP

66. Divisions of Geologic Time
• Geological time begins with Precambrian
Time. Precambrian time covers
approximately 88% of Earth’s history.

68. FOUR Eras…
• PRE-CAMBRIAN – 88% of earth’s history
• Paleozoic (ancient life)
– 544 million years ago…lasted 300 million yrs
• Mesozoic (middle life)
– 245 million years ago…lasted 180 million yrs
• Cenozoic (recent life)
– 65 million years ago…continues through present day

69. Today…
• Today we are in the Holocene Epoch of the
Quaternary Period of the Cenozoic Era.
Which unit is the largest?
Which unit is the smallest?

71. Paleozoic Era (Ancient Life)
• The Cambrian period is the 1st period of the Paleozoic Era.
“Age of the Trilobites”
• Explosion of life in the oceans began during this era.
• Most of the continents were covered in warm, shallow seas.
– Invertebrates were dominate - Trilobites
– Fish emerged during this time
– Fish led to the arrival of amphibians
• The end of the Paleozoic era is called the “Age of Amphibians”
– Early land plants including mosses, ferns and cone-bearing plants.
– The early coal forming forests were also formed during this time.

72. Paleozoic Era
• Much of the limestone quarried for building and
industrial purposes, as well as the coal deposits of
western Europe and the eastern United States, were
formed during the Paleozoic.
• The Cambrian (beginning) opened with the breakup
of the world-continent Rodinia and closed with the
formation of Pangaea, as the Earth's continents came
together once again.
– This event is thought to have caused the climate
changes that led to mass extinction event.
• The Appalachian mountains were formed during this
time.

73. Paleozoic Era
• At the end of the Paleozoic, the largest mass
extinction in history wiped out approximately
90% of all marine animal species and 70% of land
animals.
– Possible causes of this Mass Extinction Event
• Lowering of sea levels when the continents were
rejoined as Pangaea (convergent boundary)
• Increased volcanic activity (ash and dust)
• Climate changes – cooler climate

74. Trilobites
• Lived in Earth’s ancient seas
• Extinct before the dinosaurs came
into existence
• Cambrian Period is know as the
“Age of the Trilobites”

75. Brachiopods
• Marine animals that resemble clams.

76. Early Fish
Early fish did not have
jaws.
Some species of sharks
were in existence at
this time.

77. Frilled Shark that was found in Japan in January 2007. This
shark was considered a “living fossil”

78. Early Land Plants
Cone bearing plants
Mosses
Ferns

79. Mesozoic Era – Middle Life
• At the beginning of this era the continents
were joined as Pangaea.
• Pangaea broke up around the middle of this
era.
• Reptiles became the most abundant animals
because of their ability to adapt to the drier
climate of the Mesozoic Era.
– Skin maintains body fluids
– Embryos live in shells

80. Mesozoic Era
• Dinosaurs were also very active in this era.
– First small dinosaurs appeared in the Triassic
Period.
– Larger and more abundant dinosaurs appeared in
the Jurassic Period.
• Small mammals and birds also appeared
during this era.
– The mammals were small, warm-blooded animals.
Hair covering their bodies.
• These characteristics help them survive in changing
environments.

84. Mesozoic Era
• The main plant life of this time were
Gymnosperms or plants that produce seeds, but no
flowers.
– Pine Trees
• Flowering plants appeared during the END of this
era.

85. Mesozoic Era
• This era ended with a mass extinction event about
65 million years ago.
– Many groups of animals, including the dinosaurs
disappeared suddenly at this time.
• Many scientists believe that this event was caused
by a comet or asteroid colliding with the Earth.

90. Mesozoic Era – Mass Extinction
Event • Asteroid or Comet collides with Earth.
– Huge cloud of smoke and dust fills the air
– Blocks out sunlight
– Plants die
– Animals that eat plants die
– Animals that eat plant-eaters die.
• However, not all forms of life died during this event.
Many animals that you see today are descendants
from the survivors of this extinction event.

91. Dinosaurs

92. Mesozoic Reptiles

93. Mesozoic Mammals

95. Mesozoic Plants
Flowering plants
evolved towards the end
of the Mesozoic Era.

96. Cenozoic Era – Recent Life
• Began about 65 million years ago and continues today!!!!!
– Climate was warm and mild.
– Marine animals such as whales and dolphins evolved.
• Mammals began to increase and evolve adaptations that
allowed them to live in many different environments – land,
air and the sea.
– Grasses increased and provided a food source for grazing animals
• Many mountain ranges formed during the Cenozoic Era
– Alps in Europe and Himalayas in India; Rocky Mountains in the
USA

97. Cenozoic Era
• Growth of these mountains may have helped to cool
down the climate
– Ice Ages occurred late in the Cenozoic Era (Quaternary
Period).
• As the climate changed, the animals had to adapt to
the rise and fall of the oceans caused by melting
glaciers.
• This era is sometimes called the “Age of Mammals”

98. Cenozoic Era • Marine animal examples:
– Algae, Mollusks, Fish and Mammals
• Land animal examples:
– Bats, Cats, Dogs, Cattle and Humans
– Humans are thought to have appeared around 3.5 million
years ago (during the most recent period – Quaternary).
• Flowering plants were now the most common plant
life.

99. Cenozoic Mammals

100. Flowering Plants were common
during the Cenozoic Era