2. How did our
Earth form?
Science and modern technology provide
scientists with good ideas.
This study is a part of astronomy
called cosmology
3. Astronomy
The science that deals with the
material universe beyond the
Earth’s atmosphere
Cosmology
The branch of astronomy that deals
with the history, structure, and
constituent dynamics of the
universe
4. Tarantula Nebula in
Large Magellanic
Cloud
Cosmologists believe our solar system
was originally a large cloud of gas and
Dust which began to form about 4.5
billion years ago.
5. Gravity and centripetal
forces caused the cloud
to spin and take shape
as a huge disk, with our
infant Sun in its center.
6. Gravity
The natural force of attraction
exerted by a celestial body upon
objects, drawing them toward the
center
Centripetal
Moving or directed toward a center
or axis, Tending to move toward a
center; “centripetal force”
7. Centripetal , Tending to move
toward a center; “centripetal
force”forces and gravity draw
force
heavier materials (iron) toward the
center core.
Centrifugal force draws lighter
materials (silica) towards the outer
edge. Moving or directed toward a
center or axis.
9. Inner Core (solid)
Crust
(solid)
Outer core
(liquid)
Crust
(solid)
After millions
of years,
Earth has:
~ a hot, heavy,
center core
~ a cooler,
lighter, shell
~ a liquid
material in
between.
10. Magma (molten rock) flows to the surface
through large cracks or individual
volcanoes emerging as lava.
11. At the surface, lava expels hydrogen
and other gases, water vapor, and
solid materials.
12. The Sun’s rays
act on the
released gases
and distribute
them about
the Earth to
form an
atmosphere.
13. Virunga Volcanoes in Central Africa
As compression continued, volcanoes
released the intense inner heat bringing
lava and water vapor to the surface.
15. Gradually, the atmosphere cooled enough to allow the
water vapor to condense and return to the surface as rain
and eventually snow. This continued for millions of years.
The buildup of the polar icecaps has kept an almost
constant amount of water in the seas
16. The low areas filled with water forming
a gigantic pool (the world ocean)
covering about 70% of the surface of the
Earth, shaped very different than today’s.
19. Most natural
geological
change is too
slow to be
noticed,
Mount St. Helens
18 May 1980
except for
violent change such as
massive earthquakes
or volcanic eruptions.
20. 62 Miles ±
1,800 Miles ±
860 Miles ±
Earth is made of several shells. The
lithosphere floats on the mantle’s
magma (asthenosphere).
21. Lithosphere
The outer part of the Earth, consisting
of the crust and upper mantle,
approximately 62 miles thick
22. Mantle
The portion of the Earth, about 1,800
miles. Thick , which surrounds the
molten outer core of the earth
23. Asthenosphere
The region below the lithosphere,
variously estimated as being from fifty
to several hundred miles (eighty-five to
several hundred kilometers) thick, in
which the rock is less rigid than that
above and below but rigid enough to
transmit transverse seismic waves
24. The crust (upper part of the lithosphere) may
be only 3 - 10 miles thick under oceans but up
to 40 miles thick under mountains.
25. There are six major and many lesser
plates. Most volcanic eruptions and
earthquakes occur on their margins.
American
Pacific
IndoAustralian
Antarctic
Eurasian
African
26. Continental Drift
Alfred Wegener
As proposed by Wegener in 1912, the
movement of landmasses on the Earth’s
surface was known as “Continental Drift”
Theory.
28. Continental Drift Theory
Pan·gae·a
Hypothetical super-continent that includes all the
landmasses of the Earth. Continental drift breaks
Pangaea into Laurasia and Gondwanaland.
225 million years ago
29. Continental Drift Theory
Laur·a·sia and Gond·wa·na·land
Hypothetical continents that break up later into
North America-Europe-Asia and India-AustraliaAfrica-South America-Antarctica
200 million years ago
31. Continental Drift Theory
North and South America drift westward
creating Sierras and Andes mountains.
Africa creates Pyrenees, Alps, and
Apennines in southern Eurasia.
65 million years ago
32. Continental Drift Theory
Australia is completely separated from
Antarctica, while India is creating the
world’s highest mountains, the
Himalayas.
33. Established science dismissed the
theory (and Wegener) until modern
oceanographic and geologic studies
revived it in the 1960s.
The Continental Drift theory has
since evolved into the:
Plate Tectonics theory as an all
encompassing explanation for the
Earth’s multiple geological activities.
34. Plate Tectonics
A theory of global tectonics in which
the lithosphere is divided into a number
of crustal plates, each of which moves
on the plastic asthenosphere more or
less independently to collide with, slide
under, or move past adjacent plates
35. Geological Plates
Large blocks of the lithosphere that
react to tectonic forces as a unit and
moves as such
The plates drift over the uppermost,
semi-molten layer of the Earth’s
mantle like giant chunks of ice, moved
by the churnings in the interior.
36. Plates drift over
the asthenosphere.
Earthquakes
Plates
Where plates meet, inhabitants
experience geological activity
along the fault lines.
Volcanoes
37. Seismograph
An instrument for automatically
detecting and recording the
intensity, direction, and duration
of a movement of the ground,
especially of an earthquake
38. The best known fault line in the U.S. is the
San Andreas Fault in California, caused
by the Pacific Plate moving North and
the North American Plate moving South.
39. The entire West Coast is an earthquake
fault line. Approximately 40% of the
U.S. population lives and works near
the nation’s seacoasts.
40. On the San Andreas Fault, in 1906, San
Francisco was nearly destroyed by a
large earthquake and following fire.
41. In 1902, Mount Pelee
near St. Pierre,
Martinique, erupted
killing 30,000 people
within seconds.
42. Tangshan, China, 1976
In the world’s largest single earthquake
disaster, almost 700,000 people died.
43. Tsunami
Due to the depths, tsunamis
can race undetected across
open oceans in all directions
at up to 450 miles an hour!
44. When they near shore, they slow to
25 - 30 miles an hour, but build in
height and momentum as the sea floor
rises along coastlines.
They can reach 100 feet (50 ft above
and below normal sea level) as surging
walls of water.
45. Tsunamis build as the sea floor rises.
A rapidly emptying shoreline often
precedes a tsunami.
Observers should move away and to
higher ground immediately.
46. Pacific Rim Ring of Fire
Proximity to trenches and volcanoes
make the Hawaiian Islands, Alaska, and
western Pacific susceptible to tsunamis.
Populated areas can have heavy losses.
47. 26 December 2004
The world’s worst tsunami disaster
By some estimates 370,000 people
were killed
Seaquake of 9.0 magnitude
48. The volcano Krakatoa between Java
and Sumatra erupted in 1883. The
resultant tsunami, as high as 120
feet, killed 36,000.
49. Dirty rain (ash debris) from Krakatoa
orbited the Earth for many years.
50. In 1896, a tsunami in Japan
killed 27,000 and wrecked
7,000 fishing boats.
51. In 1976, a tsunami
killed 5,000 in the
Philippines.
52. Q.1. What is the definition of
oceanography?
A.1. The study of what happens on,
in, and under the seas
53. Q.2. What are the four reasons the
study of oceanography is
important to the Navy?
A.2. Political, Social, Economic,
Strategic
54. Q.3. What is cosmology?
A.3. The study of the theory of the
origin and development of the
universe
55. Q.4. How do cosmologists believe
that our solar system began?
A.4. From a large cloud of gas and
dust - a cosmic cloud
56. Q.5. What are the structural layers of
the Earth?
A.5. Inner core, outer core, and
mantle
57. Q.6. What are the two layers of the
Earth’s lithosphere?
A.6. The mantle and the crust
58. Q.7. What do scientists believe first
made the huge land mass break
up?
A.7. Fault lines in the crust caused
by stress and pressure from
below
59. Q.8. What is the name of the theory
about the formation of the
continents?
A.8. Continental drift theory
60. Q.9. What are the three phenomena
that cause great disasters?
A.9. Earthquakes, volcanoes, and
tsunamis
61. Q.10. What is a seismograph?
A.10. An instrument used to
Measure and record the
vibrations of earthquakes
62. Q.11. What is the name of the “best
known” fault on the west coast
of the United States?
A.11. The San Andreas Fault
63. Q.12. What is a tsunami?
A.12. An unusually large sea wave
caused by a seaquake or
undersea volcanic eruption
