Chapter 1,Meet Planet Earth
Geology
? Geology is the science of studying Earth.
? Geologists study the Earth’s processes,such
as:
? Volcanism.
? Glaciation.
? Stream-flow.
? Rock formation.
Geologists Also Study,
? Chemistry,to understand:
? Minerals,
? Dissolved minerals.
? Minerals resources.
? Rocks formation.
? Ground water,
Geologists Also Study,(2)
? Physics,to understand:
? Plate tectonics.
? Volcanism.
? Earthquakes.
? Landslides.
? Biology,to understand:
? How life processes integrate with other Earth
systems.
? How life has evolved.
? Fossils in the rocks.
Geologists Also Study, (3)
? Meteorology,to understand:
? Stream flow.
? Groundwater levels.
? Oceanography,to understand:
? Seafloor’s role in plate tectonics.
? Shorelines.
Geologists Also Study, (4)
? Astronomy.
? Mathematics.
? Computer sciences.
? Economics,to understand how humans
employ,
? Minerals.
? Energy resources.
What Do Geologists Do?
? They seek to understand all processes
that operate on and inside the Earth.
? They study:
? Our planet’s long history.
? Water bodies (rivers and lakes).
? Hazardous processes such as earthquakes,volcanic
eruptions,flood,and landslides.
? Rocks.
? Spot surface patterns.
? They use ground-penetrating radar,
Physical Versus Historical Geology
? Historical geology
? Chronology of events,both physical and
biological,that have occurred in the past.
? The past is the biggest clue to the present.
? Physical geology
? Concerned with understanding the processes
and the materials.
Physical Geology Also Studies
? Plate tectonics.
? Volcanism.
? Earthquakes.
? Landslides.
? Floods,
? Formation of
mineral deposits.
? Mountain-building.
? Shore erosion.
? Landscape
formation.
? Rocks.
? Minerals.
? Air.
? Seawater.
? Soil.
? Sand
How Rapid Are Geologic Processes?
? During 17~18 centuries,people believed
that Earth’s features (mountains,valleys,
oceans,rivers) were permanent and had
been produced by a few great upheavals剧
变,
? This theory is called Catastrophism.
James Hutton
? (1726-1797),now known as the father of
modern scientific geology,assembled evidence
and proposed a counterhypothesis called
gradualism.
? In 1795,he published,Theory of the Earth
with Proofs and Illustrations.”
? He proposed Uniformitarianism,which asserts
that everything must move slowly in a
repetitive,continuous cycle.
Uniformitarianism
? States that the same processes we observe
today have been operating throughout
Earth’s history.
? The cycle of uplift,erosion,transport,
deposition,solidification into rock,and
renewed uplift requires a great deal of
time for its operation.
? The Earth is 4.55 billion years old.
Catastrophism
? Recently,a thin and very unusual rock
layer,rich in the rare metal iridium,has
been discovered at many locations
worldwide.
? It indicates that a catastrophic impact
from a meteor may have occurred about
66 million years ago.
? The mass extinction of dinosaurs
occurred at that time,
? More dramatic extinctions have occurred at
other times in the past.
? The mass extinction occurring about 245
million years ago eliminated almost 90
percent of all plants and animals living at the
time.
? Events such as earthquakes,volcanic eruptions,
tsunami,floods,and landslides are local
catastrophes.
Catastrophism
Geologic Time and Earth’s Age
? Stratigraphy is the study of the structure
of sedimentary layers recording a
sequence of past events.
? The layers at the bottom of the pile are the oldest.
? Those at the top are the youngest.
? Stratigraphy identifies the relative age of
many geologic events.
? Relative age identifies position in a limited
sequence,(“This is older than that.”)
? Radioactivity can be used to establish the
absolute age of geologic events.
? Absolute age identifies position in a
universal sequence (such as our current
system of naming years in chronological
order),
Geologic Time and Earth’s Age
Geologic Time and Earth’s Age
? The Appalachians rose about 300 million
years ago.
? The modern Rockies about 70 million years.
? The most recent great ice sheets retreated
about 12,000 years ago.
The Solar System
? Earth is part of the solar system.
? Solar system consists of:
? The sun.
? Nine planets.
? Over five dozen moons,
? Vast numbers of asteroids.
? Millions of comets.
? Innumerable small fragments of rock and dust called
meteoroids.
The Planets
? The solar system’s nine planets can be divided
into two groups:
? The terrestrial planets,Mercury,Venus,Earth,Mars,
? Closest to the sun.
? Small,rocky,and dense (3g/cm3 or greater).
? The Jovian planets,Jupiter,Saturn,Uranus,Neptune,
Pluto.
? Farther from the sun than Mars.
? Much larger than the terrestrial planets,
? Much less dense.
? Pluto is a structural exception in the Jovian planets.
? Is it a planet or an asteroid?
Family Portrait of the Solar System
The planets’ orbits
More on the Jovian Planets
? All of these planets are likely to have
solid cores.
? They consist largely of the very light
elements and volatile substances:
? hydrogen.
? helium.
? carbon dioxide,
? ammonia.
Planet Temperature
? Planets and moons nearest the sun (highest
temperature) contain:
? Compounds that condense only at high temperature (iron,
silicon,magnesium,and aluminum),most bind strongly with
oxygen.
? Planets and moons more distant from the sun
(lower temperature) contain,
? Volatile substances (hydrogen and sulfur combined with
oxygen).
? Moons of Jupiter:
? Io is red because it is rich in sulfur.
? Europa,smallest of Jupiter’s four large moons,contains a
substantial amount of ice.
Temperature Gradient and Distence from the Sun
Origin of the Solar System and Earth
? Birth began in a huge volume of space
where earlier stars had exploded into
supernovas,producing a swirling cloud
of cosmic gas.
? Over millions of years,gravity slowly
gathered the thinly spread atoms into a
thicker gas.
? Near the center of this gathering cloud the
temperature and density became so great that
hydrogen atoms began to fuse to form helium
atoms (a nuclear reactor).
? The outer portion of the cosmic gas cloud
cooled and became dense enough to allow solid
objects to condense (planets,moons,and the
other solid objects of the solar system).
Origin of the Solar System and Earth
Birth of the Solar System
The gathering of atoms created a rotating cloud of dense gas
Geology
? Geology is the science of studying Earth.
? Geologists study the Earth’s processes,such
as:
? Volcanism.
? Glaciation.
? Stream-flow.
? Rock formation.
Geologists Also Study,
? Chemistry,to understand:
? Minerals,
? Dissolved minerals.
? Minerals resources.
? Rocks formation.
? Ground water,
Geologists Also Study,(2)
? Physics,to understand:
? Plate tectonics.
? Volcanism.
? Earthquakes.
? Landslides.
? Biology,to understand:
? How life processes integrate with other Earth
systems.
? How life has evolved.
? Fossils in the rocks.
Geologists Also Study, (3)
? Meteorology,to understand:
? Stream flow.
? Groundwater levels.
? Oceanography,to understand:
? Seafloor’s role in plate tectonics.
? Shorelines.
Geologists Also Study, (4)
? Astronomy.
? Mathematics.
? Computer sciences.
? Economics,to understand how humans
employ,
? Minerals.
? Energy resources.
What Do Geologists Do?
? They seek to understand all processes
that operate on and inside the Earth.
? They study:
? Our planet’s long history.
? Water bodies (rivers and lakes).
? Hazardous processes such as earthquakes,volcanic
eruptions,flood,and landslides.
? Rocks.
? Spot surface patterns.
? They use ground-penetrating radar,
Physical Versus Historical Geology
? Historical geology
? Chronology of events,both physical and
biological,that have occurred in the past.
? The past is the biggest clue to the present.
? Physical geology
? Concerned with understanding the processes
and the materials.
Physical Geology Also Studies
? Plate tectonics.
? Volcanism.
? Earthquakes.
? Landslides.
? Floods,
? Formation of
mineral deposits.
? Mountain-building.
? Shore erosion.
? Landscape
formation.
? Rocks.
? Minerals.
? Air.
? Seawater.
? Soil.
? Sand
How Rapid Are Geologic Processes?
? During 17~18 centuries,people believed
that Earth’s features (mountains,valleys,
oceans,rivers) were permanent and had
been produced by a few great upheavals剧
变,
? This theory is called Catastrophism.
James Hutton
? (1726-1797),now known as the father of
modern scientific geology,assembled evidence
and proposed a counterhypothesis called
gradualism.
? In 1795,he published,Theory of the Earth
with Proofs and Illustrations.”
? He proposed Uniformitarianism,which asserts
that everything must move slowly in a
repetitive,continuous cycle.
Uniformitarianism
? States that the same processes we observe
today have been operating throughout
Earth’s history.
? The cycle of uplift,erosion,transport,
deposition,solidification into rock,and
renewed uplift requires a great deal of
time for its operation.
? The Earth is 4.55 billion years old.
Catastrophism
? Recently,a thin and very unusual rock
layer,rich in the rare metal iridium,has
been discovered at many locations
worldwide.
? It indicates that a catastrophic impact
from a meteor may have occurred about
66 million years ago.
? The mass extinction of dinosaurs
occurred at that time,
? More dramatic extinctions have occurred at
other times in the past.
? The mass extinction occurring about 245
million years ago eliminated almost 90
percent of all plants and animals living at the
time.
? Events such as earthquakes,volcanic eruptions,
tsunami,floods,and landslides are local
catastrophes.
Catastrophism
Geologic Time and Earth’s Age
? Stratigraphy is the study of the structure
of sedimentary layers recording a
sequence of past events.
? The layers at the bottom of the pile are the oldest.
? Those at the top are the youngest.
? Stratigraphy identifies the relative age of
many geologic events.
? Relative age identifies position in a limited
sequence,(“This is older than that.”)
? Radioactivity can be used to establish the
absolute age of geologic events.
? Absolute age identifies position in a
universal sequence (such as our current
system of naming years in chronological
order),
Geologic Time and Earth’s Age
Geologic Time and Earth’s Age
? The Appalachians rose about 300 million
years ago.
? The modern Rockies about 70 million years.
? The most recent great ice sheets retreated
about 12,000 years ago.
The Solar System
? Earth is part of the solar system.
? Solar system consists of:
? The sun.
? Nine planets.
? Over five dozen moons,
? Vast numbers of asteroids.
? Millions of comets.
? Innumerable small fragments of rock and dust called
meteoroids.
The Planets
? The solar system’s nine planets can be divided
into two groups:
? The terrestrial planets,Mercury,Venus,Earth,Mars,
? Closest to the sun.
? Small,rocky,and dense (3g/cm3 or greater).
? The Jovian planets,Jupiter,Saturn,Uranus,Neptune,
Pluto.
? Farther from the sun than Mars.
? Much larger than the terrestrial planets,
? Much less dense.
? Pluto is a structural exception in the Jovian planets.
? Is it a planet or an asteroid?
Family Portrait of the Solar System
The planets’ orbits
More on the Jovian Planets
? All of these planets are likely to have
solid cores.
? They consist largely of the very light
elements and volatile substances:
? hydrogen.
? helium.
? carbon dioxide,
? ammonia.
Planet Temperature
? Planets and moons nearest the sun (highest
temperature) contain:
? Compounds that condense only at high temperature (iron,
silicon,magnesium,and aluminum),most bind strongly with
oxygen.
? Planets and moons more distant from the sun
(lower temperature) contain,
? Volatile substances (hydrogen and sulfur combined with
oxygen).
? Moons of Jupiter:
? Io is red because it is rich in sulfur.
? Europa,smallest of Jupiter’s four large moons,contains a
substantial amount of ice.
Temperature Gradient and Distence from the Sun
Origin of the Solar System and Earth
? Birth began in a huge volume of space
where earlier stars had exploded into
supernovas,producing a swirling cloud
of cosmic gas.
? Over millions of years,gravity slowly
gathered the thinly spread atoms into a
thicker gas.
? Near the center of this gathering cloud the
temperature and density became so great that
hydrogen atoms began to fuse to form helium
atoms (a nuclear reactor).
? The outer portion of the cosmic gas cloud
cooled and became dense enough to allow solid
objects to condense (planets,moons,and the
other solid objects of the solar system).
Origin of the Solar System and Earth
Birth of the Solar System
The gathering of atoms created a rotating cloud of dense gas
