Transcript Chpt8

Chapter 11:
The Dynamic Planet
I. The Pace of Change
A. The Geologic Time Scale
II. Earth’s Structure and Internal Energy
A. The Earth’s Core
B. The Earth’s Mantle
C. The Earth’s Crust
III. The Geologic Cycle
A. Defined
B. Types of Rock
IV. Plate Tectonics
I. Pace of Change
A. Geologic Time Scale
Figure 8.1
II. Earth’s Structure and Internal Energy
Earth is estimated to be around 4.6 billion years old.
Earth’s continental crust formed 4.0 billion years ago.
Earths’ interior is sorted into concentric layers, each one
distinct in either chemical composition or temperature.
II. Earth’s Structure and
Internal Energy
Figure 8.2
II. Earth’s Structure and Internal Energy
A.Earth’s Core
Inner core: solid iron, 5150 km
beneath the Earth’s surface
Outer core: molten metallic
iron and lighter in density than
the inner core, extends 2900 –
5150 km beneath Earth’s
surface.
Outer core generates 90% of
Earth’s magnetic field that
protects us from solar wind.
II. Earth’s Structure and Internal Energy
B. Earth’s Mantle
Begins 2900 km (1800
miles deep) up to 200 km
beneath Earth’s surface
Represents about 80% of
Earth’s total volume
Dominated by iron,
magnesium, and silicates
670 km (415 miles) deep is
where the upper and lower
mantle separate.
II. Earth’s Structure and Internal Energy
C. Earth’s Crust
Begins about 200 km beneath Earth’s surface
Composed of the lithosphere (includes continental and
oceanic crust)
The asthenosphere lies directly beneath the lithosphere
Continental crust is granite, very low density (2.7g/cm3).
Oceanic crust is basalt, higher density (3.0g/cm3)
II. Earth’s Structure and Internal Energy
• Structure of the Earth's crust and top most layer of the
upper mantle.
• Beneath the lithosphere is the asthenosphere. This layer,
which is also part of the upper mantle, extends to a depth
of about 200 kilometers.
III. The Geologic Cycle
Geologic Cycle: Refers to the vast cycling of rocks
and minerals that occurs in the lithosphere. It
encompasses the hydrologic cycle, the tectonic cycle,
and the rock cycle.
Factors that fuel the geologic cycle:
1. Earth’s internal heat
2. Solar energy from space
3. Earth’s gravity
III. The Geologic Cycle
III. The Geologic Cycle
A. Rock Cycle
The rock cycle is a general model that describes how
various geological processes create, modify, and
influence rocks
III. The Geologic Cycle
Rock types are identified by the processes that form them.
1.
Igneous: Rocks formed by the solidification of
magma. (granite, basalt, rhyolite)
2.
Sedimentary: Rocks formed by the alteration and
compression of old rock debris or organic
sediments (sandstone, shale, limestone)
3.
Metamorphic: Rocks formed by alteration of
existing rocks by intense heat or pressure. (marble,
quartz, slate)
III. The Geologic Cycle
A. The Rock Cycle
Figure 11.6
III. The Geologic Cycle
Igneous Rock
Types
Sedimentary Rock Types
Sedimentary Rock Types
Metamorphic Rock Types
IV. Plate Tectonics
Continental landmasses migrated to their current position
and continue to move about 2.4 inches per year.
Continental drift: Idea that the Earth’s landmasses have
migrated over the past 225 million years from a
supercontinent called Pangaea to the present configuration.
(essentially plate tectonics)
IV. Plate Tectonics
Mid-ocean ridges are the result of upwelling flows of magma
from hot areas in the upper mantle and asthenosphere (possibly
the lower mantle too).
IV. Plate Tectonics
IV. Plate Tectonics
A. Crustal Movements
Sea floor spreading builds
the mid-ocean ridges.
* Note the subduction of
oceanic crust underneath
the continental crust.
Figure 8.13
IV. Plate Tectonics
A. Crustal Movements
IV. Plate Tectonics
B. Relative Age of the Oceanic Crust
Figure 8.15
IV. Plate Tectonics
Oceanic Trenches
IV. Plate Tectonics
C. Continents Adrift
Figure 8.16
IV. Plate Tectonics
D. Earth’s Major Plates
Boundary Types:
1. Divergent
2. Convergent
3. Transform
Figure 8.17
Figure 8.20