Earth’s Internal Structure
? When a meteorite impacts a planet or moon,its
energy of motion (called kinetic energy) is
transformed into heat energy.
? As Earth grew larger and larger from
continual impacts,its temperature increased.
? Radioactive decay of materials like uranium,
thorium and potassium also added heat.
? Because Earth became partly fluid,less-
dense molten materials (silicon,
aluminum,sodium,and potassium) were
freed to migrate toward the surface.
? Denser melted materials,such as molten
iron,sank toward the center of the planet.
Earth’s Internal Structure
The Earth’s Interior
? Planet Earth has three main parts:
? At the center is the densest part,the core
(metallic iron,nickel).
? Surrounding the core is the mantle.
? Surrounding the mantle lies the thinnest and
outermost layer,the crust.
Inside Earth
The Earth’s Crust
? The crust is not uniform.
? The oceanic crust on average is about 8
km thick.
? The continental crust on average is about
45 km thick.
Investigating the Earth’s Interior
? How do we know anything about the
composition of the core and the mantle?
? By measuring the time required for earthquake
waves to travel through Earth by different
paths,we can determine the composition of the
materials through which they move,
? Iron meteorites are believed to be fragments
from the core of a small terrestrial planet that
was shattered by a gigantic impact.
The Layers of the Earth’s Interior (1)
? The inner core
? Pressures are so great that iron is solid,despite its
high temperature.
? The outer core
? Iron is molten and exists as a liquid.
? The Mesosphere
? The mantle between the bottom of the
asthenosphere to the core-mantle boundary.
? The temperature at the core-mantle boundary is
about 50000C.
The Layer of the Earth’s Interior (2)
? The Asthenosphere,
? The region of the mantle where rocks become
ductile,have little strength,and are easily
deformed,It lies at a depth of 100 to 350 km
below the surface.
? The Lithosphere,
? The outer 100 km of the solid Earth,where
rocks are harder and more rigid than those in
the plastic asthenosphere.
Plate Tectonics (1)
? The Earth gets rid of heat and keeps a
nearly constant internal temperature
through convection in the mesosphere
and asthenosphere.
? Plate tectonics theory says that Earth’s
outermost 100 km,eggshell” (the
lithosphere) is cracked in about a dozen
large pieces.
Plate Tectonics (2)
? In the 1960s,research by many geologists and
oceanographers melded into the revolutionary
hypothesis of plate tectonics,
? Plate tectonics is a group of processes by which
large fragments (plates) of lithosphere move
horizontally across the surface of the Earth,
Through their movements and interactions,
they generate:
? Earthquakes,
? Volcanism.
? Mountain-building,
? Other geologic processes.
The System Concept
? A system in any portion of the universe
that can be isolated from the rest of the
universe for observing and measuring
change.
? The simplest kind to understand is an
isolated system.
? the boundary completely prevents the
exchange of either matter or energy.
The System Concept (2)
? The nearest thing to an isolated system in
the real world is a closed system:
? exchanges energy with its surroundings,but
not matter.
? An open system can exchange both
energy and matter across its boundary.
Three kinds of Systems
Exemple of an open System
The Earth System (1)
? The Earth system is composed of:
? The geosphere (rocks).
? The atmosphere (air).
? The hydrosphere (water).
? The biosphere (life in all its forms).
? Energy and materials (like water,carbon,and minerals)
are transferred from one system to another.
? To a close approximation,Earth is a closed system.
The Earth System (2)
? Earth is only approximately a closed
system because,
? Meteorites do come in from space and fall on
Earth.
? A tiny trickle of gases leaves the atmosphere
and escapes into space.
? Earth is comprised of four open systems.
Our Planet’s,Four Spheres”
? The atmosphere:
? Nitrogen,oxygen,argon,carbon dioxide,and water
vapor.
? The hydrosphere:
? Oceans,lakes,streams,underground water,snow,
and ice.
? The biosphere:
? All of Earth’s organisms,as well as any organic
matter not yet decomposed.
? The geosphere:
? The solid Earth from core to surface,composed
principally of rock and regolith.
Earth is almost a closed system-except for Mteorites
Cyclical Movements
? The movement of materials is continuous.
? There are two key aspects to cycles:
? The reservoirs in which the materials reside.
? The flows,or fluxes,of materials from
reservoir to reservoir.
? The speed of movement differs greatly in
different cycles.
Cycling water between reservoirs
The Three Most Important Cycles
? The hydrologic cycle:
? Water in Earth’s hydrosphere.
? The rock cycle,
? Rock is formed,modified,decomposed,and reformed
by the internal and external processes of Earth.
? The tectonic cycle:
? Movements of plates of lithosphere,and the internal
processes of Earth’s deep interior that drive plate
motions.
Other Cycles
? The other cycles include the
biogeochemical cycles,
? Carbon.
? Oxygen.
? Nitrogen.
The Hydrologic Cycle
? The hydrologic cycle:
? Is powered by heat from the sun.
? Encompasses the movement of water in the
atmosphere,in the hydrosphere,on the
Earth’s surface,and in the Earth’s crust.
The Hydrologic Cycle
The Rock Cycle
? Rock is any naturally formed,nonliving,firm
and coherent aggregate of mineral matter that
constitutes part of a planet.
? The three rock families:
? Igneous rock:
? Created through the cooling and solidification of magma
? Sedimentary rock:
? Formed from deposits of sediment
? Metamorphic rock,
? Formed by the effects of pressure and heat on existing rocks
The Rock Cycle (2)
? The rock cycle describes all the processes by
which rock is:
? Formed.
? Transported.
? Decomposed.
? Reformed.
? Active volcanoes produce igneous rocks.
? Mountain ranges rise as a result of plate
tectonics.
? Weathering and erosion change the surface of
the solid Earth.
The Rock Cycle (3)
? The sediment is buried and compacted,
eventually becoming sedimentary rock.
? Deeper burial turns sedimentary rock
into metamorphic rock.
? Even deeper burial may cause some of
the metamorphic rock to melt,forming
magma from which new igneous rock will
form.
The Rock Cycle
The Tectonic Cycle
? Tectonics is the study of the movement and
deformation of the lithosphere.
? When magma rises from deep in the mantle,it
forms new oceanic crust at midocean ridges.
? The lifetime of oceanic crust is shorter than the
lifetime of continental crust.
? The most ancient oceanic crust of the ocean basins is
only about 180 million years old,and the average
age of all oceanic crust is about 70 million years old.
The Tectonic Cycle (2)
? When all oceanic crust sinks back into the
mantle,it carries some water with it.
? The water is driven off during volcanic
eruptions.
? Some constituents in the hot rock (calcium,
magnesium) are the same as those of
seawater.
The Tectonic Cycle
The cycles of the Earth system
Source of Earth Oxygen
The Nitrogen Cycle
? When a meteorite impacts a planet or moon,its
energy of motion (called kinetic energy) is
transformed into heat energy.
? As Earth grew larger and larger from
continual impacts,its temperature increased.
? Radioactive decay of materials like uranium,
thorium and potassium also added heat.
? Because Earth became partly fluid,less-
dense molten materials (silicon,
aluminum,sodium,and potassium) were
freed to migrate toward the surface.
? Denser melted materials,such as molten
iron,sank toward the center of the planet.
Earth’s Internal Structure
The Earth’s Interior
? Planet Earth has three main parts:
? At the center is the densest part,the core
(metallic iron,nickel).
? Surrounding the core is the mantle.
? Surrounding the mantle lies the thinnest and
outermost layer,the crust.
Inside Earth
The Earth’s Crust
? The crust is not uniform.
? The oceanic crust on average is about 8
km thick.
? The continental crust on average is about
45 km thick.
Investigating the Earth’s Interior
? How do we know anything about the
composition of the core and the mantle?
? By measuring the time required for earthquake
waves to travel through Earth by different
paths,we can determine the composition of the
materials through which they move,
? Iron meteorites are believed to be fragments
from the core of a small terrestrial planet that
was shattered by a gigantic impact.
The Layers of the Earth’s Interior (1)
? The inner core
? Pressures are so great that iron is solid,despite its
high temperature.
? The outer core
? Iron is molten and exists as a liquid.
? The Mesosphere
? The mantle between the bottom of the
asthenosphere to the core-mantle boundary.
? The temperature at the core-mantle boundary is
about 50000C.
The Layer of the Earth’s Interior (2)
? The Asthenosphere,
? The region of the mantle where rocks become
ductile,have little strength,and are easily
deformed,It lies at a depth of 100 to 350 km
below the surface.
? The Lithosphere,
? The outer 100 km of the solid Earth,where
rocks are harder and more rigid than those in
the plastic asthenosphere.
Plate Tectonics (1)
? The Earth gets rid of heat and keeps a
nearly constant internal temperature
through convection in the mesosphere
and asthenosphere.
? Plate tectonics theory says that Earth’s
outermost 100 km,eggshell” (the
lithosphere) is cracked in about a dozen
large pieces.
Plate Tectonics (2)
? In the 1960s,research by many geologists and
oceanographers melded into the revolutionary
hypothesis of plate tectonics,
? Plate tectonics is a group of processes by which
large fragments (plates) of lithosphere move
horizontally across the surface of the Earth,
Through their movements and interactions,
they generate:
? Earthquakes,
? Volcanism.
? Mountain-building,
? Other geologic processes.
The System Concept
? A system in any portion of the universe
that can be isolated from the rest of the
universe for observing and measuring
change.
? The simplest kind to understand is an
isolated system.
? the boundary completely prevents the
exchange of either matter or energy.
The System Concept (2)
? The nearest thing to an isolated system in
the real world is a closed system:
? exchanges energy with its surroundings,but
not matter.
? An open system can exchange both
energy and matter across its boundary.
Three kinds of Systems
Exemple of an open System
The Earth System (1)
? The Earth system is composed of:
? The geosphere (rocks).
? The atmosphere (air).
? The hydrosphere (water).
? The biosphere (life in all its forms).
? Energy and materials (like water,carbon,and minerals)
are transferred from one system to another.
? To a close approximation,Earth is a closed system.
The Earth System (2)
? Earth is only approximately a closed
system because,
? Meteorites do come in from space and fall on
Earth.
? A tiny trickle of gases leaves the atmosphere
and escapes into space.
? Earth is comprised of four open systems.
Our Planet’s,Four Spheres”
? The atmosphere:
? Nitrogen,oxygen,argon,carbon dioxide,and water
vapor.
? The hydrosphere:
? Oceans,lakes,streams,underground water,snow,
and ice.
? The biosphere:
? All of Earth’s organisms,as well as any organic
matter not yet decomposed.
? The geosphere:
? The solid Earth from core to surface,composed
principally of rock and regolith.
Earth is almost a closed system-except for Mteorites
Cyclical Movements
? The movement of materials is continuous.
? There are two key aspects to cycles:
? The reservoirs in which the materials reside.
? The flows,or fluxes,of materials from
reservoir to reservoir.
? The speed of movement differs greatly in
different cycles.
Cycling water between reservoirs
The Three Most Important Cycles
? The hydrologic cycle:
? Water in Earth’s hydrosphere.
? The rock cycle,
? Rock is formed,modified,decomposed,and reformed
by the internal and external processes of Earth.
? The tectonic cycle:
? Movements of plates of lithosphere,and the internal
processes of Earth’s deep interior that drive plate
motions.
Other Cycles
? The other cycles include the
biogeochemical cycles,
? Carbon.
? Oxygen.
? Nitrogen.
The Hydrologic Cycle
? The hydrologic cycle:
? Is powered by heat from the sun.
? Encompasses the movement of water in the
atmosphere,in the hydrosphere,on the
Earth’s surface,and in the Earth’s crust.
The Hydrologic Cycle
The Rock Cycle
? Rock is any naturally formed,nonliving,firm
and coherent aggregate of mineral matter that
constitutes part of a planet.
? The three rock families:
? Igneous rock:
? Created through the cooling and solidification of magma
? Sedimentary rock:
? Formed from deposits of sediment
? Metamorphic rock,
? Formed by the effects of pressure and heat on existing rocks
The Rock Cycle (2)
? The rock cycle describes all the processes by
which rock is:
? Formed.
? Transported.
? Decomposed.
? Reformed.
? Active volcanoes produce igneous rocks.
? Mountain ranges rise as a result of plate
tectonics.
? Weathering and erosion change the surface of
the solid Earth.
The Rock Cycle (3)
? The sediment is buried and compacted,
eventually becoming sedimentary rock.
? Deeper burial turns sedimentary rock
into metamorphic rock.
? Even deeper burial may cause some of
the metamorphic rock to melt,forming
magma from which new igneous rock will
form.
The Rock Cycle
The Tectonic Cycle
? Tectonics is the study of the movement and
deformation of the lithosphere.
? When magma rises from deep in the mantle,it
forms new oceanic crust at midocean ridges.
? The lifetime of oceanic crust is shorter than the
lifetime of continental crust.
? The most ancient oceanic crust of the ocean basins is
only about 180 million years old,and the average
age of all oceanic crust is about 70 million years old.
The Tectonic Cycle (2)
? When all oceanic crust sinks back into the
mantle,it carries some water with it.
? The water is driven off during volcanic
eruptions.
? Some constituents in the hot rock (calcium,
magnesium) are the same as those of
seawater.
The Tectonic Cycle
The cycles of the Earth system
Source of Earth Oxygen
The Nitrogen Cycle
