3. about 4.6 billion years old
Geology: the science that deals with the
dynamics and physical history of the earth,
the rocks of which it is composed, and the
physical, chemical, and biological changes
that the earth has undergone or is
undergoing
4. In most cases we will discuss geology in
terms of habitats, the places in which
organisms live
5. Oceans cover 72% of the globe and 80% of
that is still considered undiscovered
◦ 2/3 of the earth’s land mass is in the Northern
Hemisphere, which is only 61% ocean
◦ 80% of the Southern Hemisphere is ocean
6.
7. 1. Pacific - Largest and
deepest
◦ almost as large as the
other 3 combined
2. Atlantic - Second
largest
◦ similar to Indian in avg.
depth
3. Indian - Third largest
◦ similar to Atlantic in avg.
depth
4. Arctic - Smallest and
shallowest
8. All four basins are connected
This connection is most obvious when the
world is viewed form the south pole
◦ Fig 2.2
9. Oceanographers often speak of one world
ocean
World Ocean: Refers to the continuous body
of water that surrounds Antarctica as the
Southern Ocean
10.
11. The Earth and our solar system is thought to
have originated about 4.6 billion years ago
from clouds or clouds of dust.
Big Bang: A great cosmic explosion that is
estimated to have occurred 13.7 billion years
ago in which dust particles collided with each
other merging into larger particles that again
collided with each other eventually building
up the earth and other planets
12. Density: the mass of
a given volume of a
substance;
Mass/Volume
When the Earth was
formed it was most
likely molten
◦ This allowed the
interior of the Earth to
form based on density
Fig 2.3
13.
14. Core: Innermost layer of the Earth that is
composed mainly of iron
◦ Pressure at the core is more than a million times
the pressure on the Earth’s surface
◦ Made up of a solid inner core and a liquid outer
core
◦ It is thought that the swirling motions of the liquid
material in the iron-rich outer core produce the
earth’s magnetic field
15. Mantle: The layer
outside the earth’s
core
◦ most of it is thought
to be solid, but very
hot - near the point
of melting rock
◦ much of the mantle
slowly flows almost
like liquid
16. Lithosphere: The fairly rigid layer of the
earth’s surface composed of the crust and
upper-most part of the mantle.
◦ About 100 km (60 mi) thick
◦ Means “rock sphere”
◦ Broken up into a number of plates called
lithospheric plates
Lithospheric Plates: A part of the lithosphere
that can contain continental crust, oceanic
crust, or both
17.
18. Asthenosphere: The denser, more plastic
layer of the upper mantle on which the
lithosphere floats
The distinction between the lithosphere and
the asthenosphere is based on how easily the
rock flows
19. Crust: The outermost layer of the earth
◦ extremely thin in comparison to the other layers of
the earth
◦ Earth’s skin
22. Oceanic crust: The
earth’s crust that
makes up the sea
floor, generally
made up of the
mineral basalt
◦ Denser than
continental crust
◦ Thinner than
continental crust
23. Continental crust: The earth’s crust that
makes up the land portions of the world,
most continental rocks are made of granite
◦ Older than the oceanic crust
25. Sir Francis Bacon
◦ noted that the coasts of the continents on opposite
sides of the Atlantic fit together like pieces of a
giant puzzle
◦ Evidence in coal deposits, geological formations,
and fossil findings
26. Alfred Wegener
◦ German geophysicist
◦ proposed the first
detailed hypothesis of
continental drift in 1912
◦ suggested that all the
continents had once been
a single “supercontinent”
he named Pangaea
biggest obstacle was his
inability to explain how
this had occurred
27. Continental drift: The movement of
continental masses on the surface of the
earth
28. Pangaea: The single large landmass, or
supercontinent, that broke up to form today’s
continents (Fig 2.16a)
One giant sea called Panthalassa which is the
ancestor of the modern Pacific
29. Theory of plate tectonics: The process
involved in the movement of large plates on
the earth’s crust
30.
31. Mid-ocean Ridge: A continuous chain of
submarine volcanic mountains that encircles
the globe like the seams on a baseball
◦ The largest geological feature on earth
◦ Displaced at locations by cracks known as faults
◦ Occasionally these mountains rise so high that they
break the surface to form islands such as Iceland
and the Azores
◦ Earthquakes tend to cluster near the sites of ridges
32. Fault: A crack in the earth’s crust usually
formed when two pieces of crust are moving
past each other
33. Mid-Atlantic Ridge: a chain of submarine
volcanic mountains that runs down the center
of the Atlantic Ocean, closely following the
curves of the opposing coastlines.
◦ The ridge forms an inverted Y in the Indian Ocean
and runs up the eastern side of the Pacific
◦ The main section of ridge in the Eastern Pacific is
called the East Pacific Rise.
34.
35. Surveys of the sea floor also revealed a
system of trenches
Trench: A deep depression in the sea floor
◦ especially common in the Pacific
◦ Usually many volcanoes nearby
◦ Lithosphere is destroyed
36. A trench is formed when two plates collide and
one of the plates sips below the other and
sinks back down into the mantle
Subduction: The downward movement of the
plate into the mantle
Trenches are also known as Subduction Zones
37.
38. The nature of the sea floor is related to the
mid-ocean ridge
Sea floor rock right near the ridge is very
young and the rock gets progressively older
moving away from the ridge
39. Sediment: Loose
material like
sand and mud
that settles to
the bottom,
layers get thicker
at greater
distance from
the ridge
40. From time to time the earth’s magnetic field
reverses direction
◦ Reversals happen every 700,000 years on average
◦ thought to be related to movements of material in
the earth’s outer core
Many rocks contain tiny magnetic particles
Magnetic Anomalies: Magnetic bands or
“stripes” in the sea floor running parallel to
the mid-ocean ridge
41.
42. Rifts: Cracks in the oceanic crust separating
at the mid-ocean ridges
releases some of the pressure form the
underlying mantle
allows hot mantle material to melt and rise up
through the rift
magma pushes up the oceanic crust around
the rift to form the mid-ocean ridge (Fig. 2.9)
43. Sea-floor Spreading: The entire process by
which the sea floor moves away from the
mid-ocean ridges to create new sea floor
Also known as spreading centers
explains crust and sediment build up, and
magnetic anomalies
44.
45.
46. Continental margins: are the boundaries
between continental crust and oceanic crust
The shallowest part of the continental
margin is the continental shelf
consists of the shelf to shelf break,
continental slope, continental rise to
abyssal plains
47. Continental shelf
make up about 8% of the ocean’s surface
area
biologically richest part of the ocean
◦ most life and best fishing
◦ composed of continental crust
The continental shelf ends at the shelf
break where the slope abruptly gets steeper
48.
49. Two types of margins
Active Margins: zones of intense geological activity,
including earthquakes and volcanoes
◦ ex. South America’s western coast
Passive Margins: zones of little geological activity
with flat coastal plains, wide shelves and gradual
continental slopes
◦ ex. South America’s eastern coast
50.
51.
52. Ocean sediment holds many clues to the
earth’s past
Most marine sediments are of two basic
types:
lithogenous sediment: which is derived from
weathering and is usually deposited near
coasts
biogenous sediment: which consists of the
shells and skeletons of marine animals
53. some biogenous sediment is composed of
calcium carbonate (CaCO3)
This is called calcareous ooze
54. Uses the isotope C14 to age a fossil
Half-life of 5,700 C14 to tell the age of the
fossil, the percentage of C12 remains
constant
Can date something up to 50,000 - 60,000
years old
55.
56. Global warming is the increase in the average
temperature of the Earth’s near surface air
and oceans since the mid-20th century, and
its projected continuation
57. Increasing global temperature is expected to
cause sea levels to rise, an increase in the
intensity of extreme weather events, and
significant changes to the amount and
pattern of precipitation
58. Likely leading to an
increase in tropical
areas and increased
rates of desertification,
changes in agricultural
yields, modification of
trade routes, glacier
retreats, mass species
extinctions and
increases in the ranges
of disease vectors
