Transcript Earth Science Summary Lecture

Earth Science
Earth Science
• Earth Science
– Earth science is the study of planet Earth, including
its structure, components, and essential
characteristics.
– Earth science fields of study are further classified according to specific topics, such as:
• geography: study of Earth’s landforms, features, climates,
and environment.
• geology: study of Earth’s crust, including its composition and
development.
• meteorology: study of Earth’s atmosphere, including its
composition and weather patterns.
• oceanography: study of Earth’s water, including fresh and
salt water.
Earth Science
• The multidisciplinary Earth sciences are
generally classified according to one of four
general spheres, or domains, of Earth:
– lithosphere: the outermost layer of rocky land.
– hydrosphere: the combined water (solid, liquid, and
gas) found on and under the surface.
– atmosphere: the enveloping layer of protective gas
around the surface.
– biosphere: the region that supports and nurtures life
(includes portions of lithosphere, hydrosphere, and
atmosphere).
Earth Science
• Geologic Calendar
– Represents scientific understanding of age
and history of Earth.
– Primarily divided into two eons: Precambrian
and Phanerozoic.
Earth Science
• PRECAMBRIAN:
– Lasted from formation of Earth (about 4.6
billion years ago) to 570 million years ago.
– Abundant life forms: algae, bacteria, fungi,
worms, and sponges.
Earth Science
• PHANEROZOIC:
• Lasted from 570 million years ago until the
present.
• Divided into three eras:
– Paleozoic
– Mesozoic
– Cenozoic.
The Three Eras of the
PHANEROZOIC:
• Paleozoic:
– 570—245 million years ago
– Lack of fossil preservation
– Diversity of life relatively unknown
The Three Eras of the
PHANEROZOIC:
• Mesozoic:
– 245 - 66 million years ago
– First mammals and flowering plants appear
– Dinosaurs flourish
The Three Eras of the
PHANEROZOIC:
• Cenozoic:
– 66 million years ago until the present
– Mammals diversified and ruled the surface of
Earth
– Primates first appeared
The Lithosphere
• Elements
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Collection of atoms of the same type.
Simplest form of matter that:
Cannot be formed from simpler substances.
Cannot decompose into simpler substances.
Organized on the Periodic Table of the Elements:
Periodic Table contains 115 elements:
92 elements found naturally.
23 elements created artificially in laboratories.
The Lithosphere
• Minerals
– Naturally occurring, inorganic, solid substances.
– Formed when groups of atoms bond together.
– Characterized by composition and arrangement of
atoms.
– Classified by physical properties (composition):
– Crystal habit, hardness, color, cleavage, luster
– Classified by composition and crystal structure (arrangement of atoms):
– Native elements, silicates, carbonates, halides,
oxides, sulfides, sulfates
The Lithosphere
• Rocks
– Collections of minerals.
– Classified into three natural types
• igneous,
• metamorphic
• sedimentary
– Distinguished by rock structure and mineral
composition.
The Lithosphere
• IGNEOUS ROCK:
– Forms as minerals from magma (hot, liquid
rock) crystallize.
– Originates deep inside Earth.
– Is pushed to surface by magma.
– Has a texture that is determined by its rate of
cooling.
The Lithosphere
• METAMORPHIC ROCK:
– Forms as a result of extreme pressure and/or
temperature.
– Can alter and change pre-existing, older
rocks.
– Can begin as either igneous or sedimentary
rock.
The Lithosphere
• SEDIMENTARY ROCK:
– Originates as detritus (loose sediment)
formed from wind and water erosion.
– Forms as detritus accumulates and compacts
to a solid mass.
Layers of the Earth
• Layers of the Earth
– Earth is generally divided into three regions:
crust, mantle, core.
– These layers are separated by density.
Layers of the Earth
• CRUST:
– Acts as Earth’s hard Outer shell.
– Divided into two parts by density: continental and
oceanic.
– Continental:
• Located beneath surface— not covered with water
• Approximately 30—40 km thick o much older than oceanic
crust
• Consists mostly of igneous rocks o composed mostly of
granite and basalt
– Oceanic:
• Located beneath the oceans o approximately 6—11km thick
• Composed mostly of basalt
Layers of the Earth
• MANTLE:
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located under crust—is almost 3,000 km thick.
contains nearly 80 percent of Earth’s total volume.
is divided into inner and outer mantle.
has temperatures ranging from 2,500°F—5,400°F
heat from core travels through the mantle to the crust
in circles called convection currents.
– Convection currents are responsible for plate
tectonics.
Layers of the Earth
• CORE:
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located approximately 3,000 km beneath surface.
divided into inner and outer core.
outer core composed of molten nickel-iron.
inner core is solid because of intense pressure.
temperatures reach 6,700°F.
Outer core spins around inner core with rotation of
Earth.
– Earth’s magnetic field is generated by rotation of ions
in molten core.
Plate Tectonics
• Plate Tectonics
– Lithosphere broken into large, rigid plates.
– major plates: African, North American, South American,
Eurasian, Australian, Antarctic, Pacific
– minor plates: Arabian, Nazca, Philippines
– Seismic energy from two plates interacting with each other
causes earthquakes. Intensity of earthquakes measured on the
– Richter scale:
• categorizes earthquakes on a numeric scale.
• each increase in number represents a 30x increase in energy
release.
– Plates interact by colliding into, moving away from, and rubbing
against each other. These interactions create earthquakes,
volcanoes, mountain ranges.
Plate Tectonics
• CONVERGENT PLATE BOUNDARIES:
– Occur when plates collide or move into each
other.
– Results include earthquakes, Andes and
Himalayan mountains.
Plate Tectonics
• DIVERGENT PLATE BOUNDARIES:
– Occur when plates move away from each
other.
– Results include oceanic ridges, East African
rift valley, Rio Grande rift.
Plate Tectonics
• TRANSFORM PLATE BOUNDARIES:
– Occur when two plates rub against, or move
parallel to, each other.
– Results include earthquakes along the San
Andreas Fault.
Plate Tectonics
• Distribution of Earth’s land developed through
movement of lithospheric plates.
250 million
years ago
All land is connected t-one super continent
(Pangaea)
200 million
years ago
100 million
years ago
Pangaea divides into northern Laurasia
and southern Gondwanaland
Laurasia and Gondwanaland break apart
50 million
years ago
continents closely resemble current
distribution
Geologic Processes
• SURFACE-MODIFYING PROCESSES:
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leave behind evidence of activity on Earth’s surface.
are dynamic processes that continually change Earth.
can be slow and steady (e.g., erosion, sediment transport).
can be sudden and disastrous (e.g., earthquake, volcanoes).
human activity can speed up, cause, or otherwise affect natural
geologic processes:
• farming and mining can speed up wind and water erosion.
• deforestation can increase the occurrence of landslides and
mudflows.
• global warming and climate change can both lead:
– directly to rising temperatures, melting glaciers, and rising sea levels.
– indirectly to floods, earthquakes, hurricanes, and increased volcanism.
SURFACE-MODIFYING
PROCESSES:
• Tectonism
– fracture and deformation of Earth’s crust
• Volcanism
– molten rock reaches surface
– basaltic lava flows (fluid eruptions of molten rock)
– pyroclastic flows (eruptions of solid debris such as
rock and ash)
• Water-modifying / fluvial force
– water erosion
– sediment transport
– sandbar formation
SURFACE-MODIFYING
PROCESSES:
• Aeolian process
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wind erosion
rock carving and shaping
sand dune formation
sediment transport
• Glacial process
– landscape leveling
– sediment and rock transport
– creation of fjords, crevasses, cliffs, rock formations
• Gravitational processes
– landslides, mudflows, avalanches