Transcript Historical Geology

Ch. 1 Dynamic and Evolving
Earth
ESCI 102
Spring 2005
Lec. 1 Review/Summary Questions
1) What are the five subsystems of Earth?
2) Are there any more details known about
early Earth?
3) If everything in the universe is moving
away from us, why is it that we are not
the center of the universe?
4) How has Earth’s core stayed hot for so
long?
Earth’s Interior Layers
• Crust - 5-90 km
thick
– continental and
oceanic
• Mantle
– composed
largely of
peridotite
– dark, dense
igneous rock
– rich in iron and
magnesium
• Core
– iron and a small
amount of nickel
Earth’s Interior Layers
• Crust - 5-90 km
thick
– continental and
oceanic
• Mantle
– composed
largely of
peridotite
– dark, dense
igneous rock
– rich in iron and
magnesium
• Core
– iron and a small
amount of nickel
• Lithosphere
– solid upper
mantle and crust
• Asthenosphere
– part of upper
mantle
– behaves
plastically and
slowly flows
Earth’s Interior Layers
• Lithosphere
– solid upper
mantle and crust
– broken into
plates that
move over the
asthenosphere
• Asthenosphere
– part of upper
mantle
– behaves
plastically and
slowly flows
Earth’s Crust
• continental (20-90 km
thick)
– density 2.7 g/cm3
– contains Si, Al
• oceanic (5-10 km
thick)
– density 3.0 g/cm3
– composed of basalt
Plate Tectonic Theory
• Lithosphere is broken into individual pieces
called
plates
• Plates move over the asthenosphere
– as a result of underlying convection cells
Modern Plate Map
Plate Tectonic Theory
• at plate boundaries
– volcanic activity occurs
– earthquakes occur
• movement at plate boundaries
– plates diverge
– plates converge
– plates slide sideways past each other
Plate Tectonic Theory
• types of plate boundaries
Cont.-Cont.
Divergent Convergent Cont.-Ocean
Convergent
Transform
Ocean-ocean
Convergent
Plate Tectonic Theory
influence on geological sciences:
• revolutionary concept
– comparable to evolution
• provides a framework for
– interpreting many aspects of Earth on a global
scale
– relating many seemingly unrelated phenomena
– interpreting Earth history
Atmosphere Solid Earth
Plate Tectonics and
Earth Systems
• plate tectonics is driven by convection in the
mantle
– and in turn drives mountain building
– and associated igneous and metamorphic
activity
• arrangement of continents affects:
– solar heating and cooling,
– and thus winds and weather systems
• rapid plate spreading and hot-spot activity may
release volcanic carbon dioxide and affect
global climate
Biosphere Hydrosphere
Plate Tectonics and
Earth Systems
• continental arrangement affects ocean
currents
• rate of spreading affects volume of midoceanic ridges and hence sea level
• placement of continents contributes to the
onset of ice ages
• movement of continents creates corridors or
barriers to migration, the creation of
ecological niches, and transport of habitats
into more or less favorable climates
Theory of Organic Evolution
• provides a framework for understanding
the history of life
• Darwin’s On the Origin of Species by
Means of Natural Selection, published
in 1859
• revolutionized biology
Central Thesis of Evolution
• all present-day organisms
– are related
– descended from organisms that lived
during the past
• Natural Selection is the mechanism that
accounts for evolution
– results in the survival to reproductive age
of those organisms best adapted to their
environment
History of Life
• Fossils are the remains or traces of onceliving organisms
– demonstrate that Earth has a history of life
– most compelling evidence in favor of
evolution
Geologic Time
• human perspective
– seconds, hours, days, years
• ancient human history
– hundreds or even thousands of years
• geologic history
– millions, hundreds of millions, billions of
years
Geologic Time Scale
• resulted from the work of many 19th
century geologists who
– pieced together information from numerous
rock exposures
– constructed a sequential chronology based on
changes in Earth’s biota through time
• the time scale was subsequently dated in
years
– using radiometric dating techniques
Geologic
Time Scale
Uniformitarianism
• Uniformitarianism is a cornerstone of geology
– present-day processes have operated throughout
time
– physical and chemical laws of nature have
remained the same through time
• to interpret geologic events
– we must first understand present-day processes
and their results
How Does the Study of Historical Geology
Benefit Us?
• survival of the human species depends on
understanding how Earth’s various subsystems work
and interact
– how we consume natural resources and interact with the
environment determines our ability to pass on this standard
of living to the next generation
– our standard of living depends directly on our consumption
of natural resources that formed millions and billions of years
ago
• study what has happened in the past, on a global
scale, to try and determine how our actions might
affect the balance of subsystems in the future
Present
Note:
Best data set available.
http://vishnu.glg.nau.edu/rcb/globaltext.html
Latest Precambrian / Early
Paleozoic
Supercontinent Rodinia, centered
about the south pole, breaks
apart. North America (Laurentia),
Baltica, and Siberia moved
North.
Marine Invertebrates.
North America: arc on the south.
Baltica and Siberia moved in
from the SE.
Texas (505-570 Ma): Flat plain;
remnants of eroded collisional
belt (Llano). Shallow marine seas
across much of Texas. Sandy
sediment onshore, limestone
offshore. Trilobites, brachiopods.
http://vishnu.glg.nau.edu/rcb/globaltext.html
Latest Precambrian / Early
Paleozoic
Supercontinent Rodinia
continues to break apart. Pieces
move north.
-Fish.
-Glaciation.
North America: Numerous plates
and continental blocks move in
from the south and east. The
Taconic arc collides, forming the
Taconic orogeny.
Texas 438-505 Ma: Shallow
marine seas across much of
inland Texas. Warm-water
limestone. Corals, brachiopods.
http://vishnu.glg.nau.edu/rcb/globaltext.html
Middle / Late Paleozoic
Remains of Rodinia (Gondwana)
move northward to collide with
Laurasia -- creating the super
continent Pangaea and the Tethys
Ocean.
First land-plants.
Baltica collides with North America
in the Caledonian-Acadian orogeny.
Texas 403-438 Ma: Shallow marine
seas across much of west Texas limestone. Corals, brachiopods.
http://vishnu.glg.nau.edu/rcb/globaltext.html
Middle / Late Paleozoic
Most drifting Rodinia blocks
assembled into the super continent
of Laurussia.
Amphibians. Fish really get going.
Ferns.
Glaciation.
North America: Caledonian-Acadian
orogeny marks assemblage of
Laurussia. Gondwana closed in from
the south. An arc formed along
western North America.
Texas 360-408 Ma: shallow marine
sandstones and limestones in west
Texas.
http://vishnu.glg.nau.edu/rcb/globaltext.html
Middle / Late Paleozoic
Gondwana, with a large,
developing glacier, nears
southern Laurussia.
Fern-forests.
North America: The Antler arc
collides with western North
America creating the Antler
orogeny.
Texas 320-360 Ma: shallow
marine seas inland. Shales and
limestones.
http://vishnu.glg.nau.edu/rcb/globaltext.html
Middle / Late Paleozoic
Rodinia blocks of Laurussia and
Siberia collide to form Laurasia.
Reptiles.
North America: Gondwana
collides from the south. The
resulting Appalachian, Ouachita,
Marathon, Ural, Variscan, and
Hercynian orogenies formed some
of the largest mountains of all
time. The Ancestral Rockies form.
Texas 286-320 Ma: Ouachita
Mountains. Collision formed inland
basins filled by seas. Limestone,
sandstone, shale.
http://vishnu.glg.nau.edu/rcb/globaltext.html
Latest Paleozoic / Early
Mesozoic
The supercontinent Pangaea
dominates the Permian Earth, lying
across the equator.
Extinctions! Trilobites go away.
North America: A new arc
approaches western North America.
A new spreading center forms as
Cimmeria rifts from Gondwana and
opens the Tethyian Ocean.
The western fringe of Pangaea lay
along the eastern margin of the
Pacific "ring of fire” subduction zone.
Texas 245-286 Ma: Shallow marine
inland of mountains. Reefs.
Evaporites. Red shales.
http://vishnu.glg.nau.edu/rcb/globaltext.html
Latest Paleozoic / Early
Mesozoic
Mammals.
North America: Arc collision along
western edge forms the Sonoman
orogeny.
As the Tethys Ocean expands,
Cimmeria (Turkey, Iran, and
Afghanistan) move
northward towards Laurasia.
Texas 208-245 Ma: shales and
sandstones in NW. Start opening
the GOM - red sandstone, shale,
evaporites.
http://vishnu.glg.nau.edu/rcb/globaltext.html
Middle Mesozoic
Pangaea rotates; different
components at different rates / in
different directions -- rifts form.
Birds.
North America: Southern North
Atlantic Ocean opens, continuing
west into the Gulf of Mexico.
The Cordilleran arc develops along
Pacific margin.
Arc forms on western side. Nevadan
orogeny begins. Cimmeria begins
collision with Laurasia - Cimmerian
orogeny.
Texas 144-208 Ma: Change in
sediment direction. Shallow water
deposition / evaporites in GOM.
http://vishnu.glg.nau.edu/rcb/globaltext.html
Middle Mesozoic
The Atlantic continues to expand
as Pangaea breaks up.
The Cimmerian orogeny
continues.
North America: Arcs and micro
continents slam into western
region. Laramide orogeny in
Rockies.
Texas 66-144 Ma: Influx of
sediment from Rockies. Shallow
Cretaceous sea way across Texas.
Shallow limestones, shales.
http://vishnu.glg.nau.edu/rcb/globaltext.html
Late Cretaceous /
Present
Rifts separate Africa and South
America and then India,
Australia, Antarctica. North
America rifts from Europe.
Old Gondwana lands (Africa,
India, Australia) move north
toward Eurasia, closing the
Tethys Ocean and forming the
Alpine-Himalayan mountains.
The Atlantic lengthens / widens,
the Sevier orogeny continues,
and the Caribbean arc forms.
Texas 65-144 Ma: continuing
shallow limestone and shale
deposition to the southeast (from
Rockies).
http://vishnu.glg.nau.edu/rcb/globaltext.html
Paleocene / Eocene
Himalayan Orogeny. Alps and
Pyrenees form.
The modern patterns of Planet
Earth appear.
Atlantic continues to open.
Rocky Mountains grow.
Texas 65 - 35 Ma: shale and
sandstone in southeast region
prograde shoreline (from the
Rockies). Volcanic activity in
Panhandle.
http://vishnu.glg.nau.edu/rcb/globaltext.html
Oligocene and Miocene
Orogeny continues in
the Mediterranean region and
India nears its junction with
southern Asia.
Antarctica isolated.
Southwestern North America
intercepts the East Pacific Rise
and a great extensional event, the
Basin and Range orogeny begins.
Texas 35-5 Ma: continued
sandstone/shale deposition and
progradation of shoreline (erosion
of Rockies)
http://vishnu.glg.nau.edu/rcb/globaltext.html
Present
Note:
Best data set available.
http://vishnu.glg.nau.edu/rcb/globaltext.html