APES Ms. Tooker Earth Science Concepts Geologic time scale Plate tectonics Earthquakes Volcanism Seasons Solar intensity Latitude/longitude.
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Transcript APES Ms. Tooker Earth Science Concepts Geologic time scale Plate tectonics Earthquakes Volcanism Seasons Solar intensity Latitude/longitude.
APES
Ms. Tooker
2015
Earth Science Concepts
Geologic time scale
Plate tectonics
Earthquakes
Volcanism
Seasons
Solar intensity
Latitude/longitude
Geologic Time Scale
Two time scales are used to measure the age
of Earth.
Sequence of layering of the rocks (strata)
and evolution of life
Radiometric time scale-natural
radioactivity of chemical elements in rocks
Geologic Time Scale
Organized into various units according to
events that took place in each period
Usually separated by major geologic or
paleontological events (mass extinctions)
Largest unit of time- eon
Eon Eras Periods Epochs Stages
Geologic Time Scale
Key Principles of the Geologic Time Scale
Rock layers (strata) are laid down in
succession with each strata representing a
“slice” of time.
The principle of superposition- any given
layer is probably older than those above it
and younger than those below it.
Is the Geologic Time Scale
perfect??
NOOOO!!!
Layers are often eroded, distorted, tilted, or
uneven
Layers laid down at the same time in
different areas can have entirely different
appearances
A layer from any given area represents only
part of Earth’s history
Earth Structure
Formed 4.6 billion years ago
Third planet from the sun in the solar system
Only planet known to support life
Earth Structure
Biosphere- includes all forms of life (plants and
animals) both on land and in the sea
Hydrosphere- includes all forms of water (fresh and
saltwater, snow, ice)
Lithosphere- includes the outermost shell of the
planet (crust and upper mantle), approximately 62
miles thick
Crust
Makes up 0.5% of Earth’s total mass
Floats on top of the mantle
Oceanic crust
From Earth’s surface to 7 miles down
Relatively cold
Rocky
Brittle
Fractures easily in earthquakes
Continental Crust
Extends from Earth’s surface to 20-30 miles down
Appears stratified (layered)
Composed of volcanic, sedimentary, and granitetype rocks
Older areas may be metamorphic
Mantle
Most of Earth’s mass
Composed of iron, magnesium, aluminum, and
silicon-oxygen compounds
Over 1800˚F
Mostly solid
Upper third (asthenosphere) is more plastic-like
Plate Tectonics
Continental drift theory- 1915, Alfred Wegener
All present-day continents originally formed one
landmass (Pangaea).
Based on:
Fossilized tropical plants discovered beneath
Greenland’s icecaps
Tropical regions on some continents has polar climates
in the past, based on paleoclimatic data
The continents fit together like pieces of a puzzle
Plate Tectonics
Seafloor Spreading Theory- 1960s
Alternating patterns of magnetic properties were
discovered in rocks found on the seafloor.
Dating of the rocks indicated that as one moved away
from the ridge, the rocks became older.
New crust was being created at volcanic rift zones.
Plate Tectonics
Earth’s plates float and move on the viscous
asthenosphere
Subduction zones- where two plates meet and move
towards each other
Earth’s Major Plates
Transform Boundaries
Occur where plates slide past each other.
Friction and stress buildup from the sliding plates
and earthquakes occur
Example: San Andreas Fault (Pacific Plate and North
American Plate)
Divergent Boundaries
Occur where two plates slide apart from each other
with the space that was created being filled with
molten magma from below.
Can create massive fault zones in the oceanic ridge
system-frequent oceanic earthquakes
Example- Mid-Atlantic Ridge and the East Pacific
Rise
Convergent Boundaries
Occur where two plates slide toward each other,
forming a subduction zone (one plate moving under
the other) or an orogonic belt (two plates collide and
compress)
Oceanic-Continental
Convergence
Subduction zone- basaltic oceanic crust is more
dense than granite continental crust.
Examples- deep ocean trenches, stratovolcanoes and
Volcanic Mts. on Land. ex.
Cascade Mountains in the Pacific Northwest US
Oceanic-Oceanic Convergence
An island arc (curved chain of volcanic islands rising
from the deep seafloor and near a continent)
Created by subduction processes
Examples- Japan, Aleutian Islands in Alaska
Continental-Continental
Convergence
Mountain ranges are formed when plates collide
Earth’s crust is compressed and pushed upward
Examples- Himalayas
Earthquakes
Two classes of seismic waves: body waves
and surface waves
Body waves travel through the interior of
Earth
Two types of body waves:
P waves
S waves
Earthquakes
P waves:
Travel through Earth
Caused by expansion and contraction of
bedrock
Earthquakes
S waves:
Produced when material moves either vertically
or horizontally
Travel only within the uppermost layers of
Earth (along its surface)
Earthquakes
Surface Waves:
Produce rolling and/or swaying motion and are
slower than P or S waves.
Cause ground motion and damage.
Earthquakes
The severity of an earthquake depends upon:
The amount of potential energy that has been
stored
The distance the rock mass moved when the
energy was released
How far below the surface the movement
occurred
The makeup of the rock material
The Richter Scale
Tsunamis
A series of waves created when a body of water is
rapidly displaced, usually by an earthquake
Generated when plate boundaries move abruptly
move
Subduction-zone-related earthquakes generate the
majority of all tsunamis
Volcanoes
Active volcanoes produce magma (melted rock) at
the surface.
About 95% of volcanoes occur at subduction zones
and mid-oceanic ridges
About 5% occur at hot spots
Produce ejecta (lava rock and/or ash)
Molten lava
Toxic gases- steam, carbon dioxide, sulfur dioxide
Atmospheric Effects of Volcanoes
General Volcano Structure
Seasons, Solar Intensity,
and Latitude
Factors that affect the amount of solar energy at the
surface of Earth:
Earth’s rotation (once every 24 hours)
Earth’s revolution around the sun (once per year)
Atmospheric conditions
Summer Solstice
Sun rises higher in the sky
Stays above the horizon longer
The sun’s rays strike the ground more directly (less
of an angle)
Winter Solstice
Northern hemisphere is titled away from the sun
The sun rises lower in the sky
Stays above the horizon for a shorter period of time
Earth is closest to the sun during the Northern
Hemisphere winter (Dec.-Feb.)
Earth is farthest away during the Northern
Hemisphere summer (June-Aug.)
Seasons are NOT caused by Earth’s distance from
the sun!!
Seasons are created by the angle of sunlight hitting
the Earth.