Praxis Review for
Earth Science
By
Frank H. Osborne, Ph. D.
Kean University
Union, New Jersey
fosborne@kean.edu
908-737-4002
Compiled and expanded by Suzanne Leone, Raleigh NC (2012)
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Praxis Review for Earth Science
by Frank H. Osborne, Ph. D.
Earth Materials and
Surface Processes
23-27 questions
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Earth Materials
Minerals
•A mineral is a naturally occurring substance
with characteristic physical and chemical
properties.
•Nearly all rocks are composed of minerals.
•Polymineralic rocks are composed of more than
one mineral, ex. granite.
•Monomineralic rocks are composed of only one
mineral, ex. limestone.
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Earth Materials
Mineral Composition
Minerals are composed of elements.
•
•
•
Some minerals contain only one element (Ex: copper, sulfur
and graphite (carbon)).
Most minerals are made up of only a few elements.
Oxygen is the most common element by weight and volume.
Silicon is second most abundant by weight.
These eight minerals form most rock:
amphibole, biotite, muscovite, olivine, orthoclase, plagioclase,
pyroxene, and quartz
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Earth Materials
Properties of Minerals
Differences in properties are used to categorize
and identify minerals.
• Minerals have a characteristic crystalline
structure, in many cases the silicon-oxygen
tetrahedron.
• The most basic characteristics are perceived
through observation and polarizing microscopy
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Earth Materials
Properties of Minerals
Color – this varies depending on the chemicals present
and is the least informative in identifying a mineral
Luster – what the surface looks like in the light
Specific Gravity – how heavy it feels, its heft (weigh in
known beaker of water)
Cleavage – the pattern when broken; planes or
conchoidal
Fracture - the shape and texture of the surface formed
when a mineral is(C)broken
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Earth Materials
Properties of Minerals, continued
Crystal Form – shape of crystal, shape the mineral
would take if it had room to grow in a cavity – some
minerals have a number of different crystal shapes
Tenacity – toughness, how cohesive the mineral is,
if it falls apart
Hardness – what it can scratch and
what scratches it (see graph)
Mohs Hardness Scale (1812)
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Earth Materials
Properties of Minerals, continued
Transparency - the ability to transmit light.
• Depending on a number of things,
rocks & minerals can also transmit light.
Many rocks that are opaque when in a chunk, are
translucent when cut into very thin slices.
• Gems stones are often valued on how clear, or
transparent they are.
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Earth Materials
Special Properties of Minerals
Magnetism
Chatoyancy (optical reflectance effect seen in certain gemstones.
Coined from the French "œil de chat," meaning "cat's eye“)
Fluorescence (emit visible light when exposed to ultraviolet light)
Odor (sulfur and sulfides-egg; arsenic-garlic; wet clay)
Streak color (when rubbed on a streak plate; non-white minerals only)
Flame color (when burned and viewed with a spectroscope)
Conductivity
Alkalinity (the use of hydrochloric acid on sulfides or carbonates like
limestone to liberate CO2(C)bubbles)
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Rock Formation
• Rocks are classified by the processes under
which they were formed.
• All rocks begin as igneous rocks, and are then
transformed into metamorphic or sedimentary
rocks.
• One or more minerals make up each rock.
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Rock Formation
The Rock Cycle relates the three types of
rocks. The rock cycle is driven by interactions
between plate tectonics and the hydrologic cycle.
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Earth Materials
The Rock Cycle
• Any one rock type can change into any other
rock type.
• There is no preferred direction of movement of
materials in the rock cycle for any one mass of
material.
• There is no exact point of separation between
the rock types.
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Earth Materials
The Rock Cycle
• Sedimentary rocks often contain sediments or
fragments which have varied origins.
• The composition of some rocks suggests that
the materials in the rock (the sediments or
minerals) have undergone multiple
transformations within the rock cycle.
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Weathering and Erosion
Weathering is the breakdown of rocks to form
particles called sediment.
• Physical weathering is the breakdown of rock
without chemical changes
− Freezing and thawing (frost action)
− Thermal expansion and contraction
• Chemical weathering is the breakdown of rock
by chemical action
− Oxidation
− Hydration
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− Solution by acids
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Weathering and Erosion
Factors affecting weathering are:
• Exposure – more exposure means faster weathering
• Particle size – the smaller the particles, the greater
the surface area
• Mineral composition – some minerals (quartz) are
more resistant to weathering than others (mica and
feldspar)
• Climate – warmth and moisture enhance weathering
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Weathering and Erosion
Erosion is the process by which sediments are
obtained and transported.
• Transporting agents include water (streams),
glaciers, waves, density currents in water, wind,
and people.
• Driving forces include gravity and change of
potential to kinetic energy.
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Weathering and Erosion
Stream Erosion
Stream water carries sediments.
• Dissolved minerals are carried in solution.
• Small solid particles are carried in suspension.
• Large solid particles are moved by rolling or
bouncing along on the bottom of the stream.
The ability to carry sediment depends on velocity.
Stream velocity depends on the gradient (slope)
and discharge (volume) of the stream. On a curve,
it is fast on the outside and slow on the inside. 17
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Weathering and Erosion
Stream Erosion
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Weathering and Erosion
Wind Erosion
• When wind carries sediment, it
forms dunes.
abc-of-mountainbiking.com
Hubbard Glacier,
Alaska
Glacial erosion
• A glacier can carry large amounts of dirt.
• When the glacier stops moving,
it drops the dirt, forming a moraine.
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Weathering and Erosion
Glacial Erosion
• There is a moraine in New
Jersey left over from the last
ice age.
• The same glacier also
formed Long Island.
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Soil
Soil is a product of weathering and erosion.
Soil Types
• Residual soil forms from the weathering of rocks
nearby.
• Transported soil is brought in by erosion.
Soil layers develop over as much as 1,000 years.
Soil generally tends to reflect the composition of
the rocks below, plus decomposed organic matter.
Erosion can also destroy nutritive soil (hūmus).
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Soil
A soil horizon is a vertical layer of soil with certain
characteristics.
• “Lower” horizons result from
weathering
humus–uniformly dark, spongy, jelly-like, organic
matter that will break down no further
topsoil – The uppermost 15-20 cm of dirt; includes
humus and various amounts of sand and clay
eluviation layer – the layer where dissolved or
suspended material is moved down or
sideways when rainfall exceeds evaporation
subsoil – a layer of material that is breaking down into
soil; similar in texture to compost
regolith – a layer of loose, heterogeneous mineral
material covering the bedrock.
bedrock – solid, unweathered rock
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Deposition
Deposition is also known as sedimentation.
Deposition occurs when the velocity of water, wind or
other erosional system decreases.
Deposition depends on:
• Particle size--heavier particles sediment faster
• Shape--spherical particles sediment faster
• Density--denser particles sediment faster
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Deposition & Sedimentation
Rock layers are formed by sediments.
The particle size determines the rock type.
Boulders, gravel, pebbles --> conglomerate
Sand --> sandstone
Silt --> siltstone
Colloids, clay --> shale
Colloids, chemical sediments --> limestone
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Deposition
Deposition by moving water
• When a river enters the ocean,
the velocity decreases.
• Sediments are deposited
and form a delta.
• Ex: Mississippi River Delta.
http://www.sln.org.uk/geography/schools/
blythebridge/gcseriversrevisionlc.htm
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Rock Formation
Rocks are the solid material that makes up the
Earth.
There are three types:
• Sedimentary Rocks--formed by solid sediments
weathered from pre-existing rocks
• Igneous Rocks--formed by cooling of liquid rock
• Metamorphic Rocks--formed by transformation of
igneous or sedimentary rocks by reheating or pressure
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Sedimentary Rock Formation
• Cementation--larger particles
are cemented by minerals
precipitated out of the water
• Compression--very small
particles are compressed by
immense weight of water and
sediment layers above them;
aka compaction
• Chemical action--ionic materials precipitate out of
the water
• Biological processes—precipitation of minerals by
biological organisms (molting, elimination)
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Sedimentary Rock Properties
•
•
•
•
contain one or more sediments
may have organic origin (example: coal)
form layers called strata
frequently contain fossils
Particles of sedimentary rocks resemble the
sediments they came from.
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Types of Sedimentary Rocks
Three major groups of sedimentary rocks:
• Detrital rocks form from sediments washed in
by water, such as gravel, sand and mud.
Ex: sandstone, shale.
• Chemical sedimentary rocks have crystalline
texture. Ex: limestone, dolostone, gypsum, salt
• Biochemical sedimentary rocks: clastic
(limestone from shells), chert, coal
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Igneous Rock Properties
• non-sedimentary in origin
• form by solidification or crystallization of liquid
rock called magma
• Longer cooling time causes big crystals in the
rock. Shorter cooling time causes small crystals
in the rock.
• Texture depends on the size of the crystals.
• Along with composition, texture is an important
identifier.
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Igneous Rocks
Bowen’s reaction series accounts for the
crystallization of intermediate and felsic magmas
from an original basaltic (mafic) magma over time.
high in
Mg and Fe
high in
Al and Si
Higher temperature magma tends(C)
to2003-2012
originate
deeper.
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Density and dark color decrease with temperature.
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Examples of Igneous Rocks
•
•
•
•
•
granite
pumice
scoria
gabbro
basalt
•
•
•
•
rhyolite
dacite
andesite
obsidian
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Metamorphic Rock Properties
• non-sedimentary in origin.
• a response to heat and pressure within the Earth’s
crust (from plate collisions, mountain building and
sometimes localized heating such as with volcanic
eruptions)
• form from recrystallization of pre-existing rocks
• often show banding where like crystals are arranged
in layers
• a distorted structure caused by curving and folding
of the bands (they look funky!)
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Types of Metamorphic Rocks
• Foliated rocks have crystals arranged in
parallel planes. Examples: slate, schist, gneiss.
• Nonfoliated rocks do not have a preferred
orientation among their minerals. Examples:
marble, quartzite, greenstone.
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Metamorphic Rocks
Regional metamorphism
• occurs over a wide area
• gradation from low to high metamorphism
depending on the levels of temperature and pressure
involved.
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Metamorphic Rocks - Gneiss
Steps leading to the formation of gneiss
• Most gneiss begins with recrystallization of clayrich sedimentary rocks during regional
metamorphism.
• Gneisses are composed mainly of quartz and/or
feldspar, which cause the light bands.
• The dark bands come from biotite and hornblende.
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Metamorphic Rocks - Marble
limestone CaCO3 --> limestone marble
dolomite CaMg(CO3)2 --> dolomite marble
Limestone marble reacts with the acid test.
Dolomitic marble also reacts with the acid test,
but it must be powered first.
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Civilization and Earth Materials
Minerals are used in a variety of human
activities.
• Humans use fossil fuels for the major part of their
energy needs. These include coal, oil and natural
gas.
• Rocks are quarried and used as building stones and
pavement.
Earth resources are not renewable. They cannot
be restored easily in your lifetime.
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Landscape development
Landscapes are the features of the surface of
Earth.
• slope of the land
• shape of surface features
• stream drainage patterns
• stream slope
• soil characteristics
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Landscape development
• Landscape characteristics can be measured
using actual observations, maps, aerial
photographs or satellite images
• Gradients, slopes and profiles are given on
topological maps (contour maps)
• Major landscape types are mountains, plateaus
and plains
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Landscape development
Leveling forces break down rocks and
transport material on the Earth’s surface.
• Weathering – the breaking down of materials through contact
with the Earth's atmosphere, organisms, and waters
• Deposition – process of adding transported material to a landform
• Erosion – the removal of weathered rock materials from their
source area
• Mass wasting – the downslope movement of rocks, sediments, or
soil under the influence of gravity (landslide)
• Subsidence – a lowering of a region of land caused by forces in
the crust or by tectonic interaction
• Uplift – a raising up of a region of land caused by forces in the crust
or by tectonic interaction
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Landscape development
• Glaciers produce U-shaped valleys and deposit
soil with a wide range of particle sizes.
• Streams may be seasonal in arid climates, or have
internal drainage where streams deposit water into
a basin rather than leading to the ocean. Ex: Great
Salt Lake, Utah
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Maps
Geologic features can be represented by
photographs, as well as topographic and
geological maps.
Maps are interpreted using distance scales, and
colors to represent features.
Topographic maps indicate locations of equal
altitude using contour lines. The distance between
lines shows the grade of a slope.
Geologic maps use colors and symbols to represent
rock ages and structures.
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Landscape development
Natural factors
• Bedrock greatly influences the landscape above it.
Stream drainage patterns indicate information
regarding the contour of the bedrock below.
• Different types of rock have different degrees of
resistance to weathering and erosion.
• Climate affects the rate of change of a landscape.
Warmth and moisture accelerate erosion.
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Landscape development
Human factors
• Removal of forests for development leads to
accelerated erosion of soil when it rains.
• Acid rain causes increased chemical weathering of
rocks. Example: accelerated erosion of limestone.
• Environmental conservation can help conserve limited
natural resources.
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Natural Hazards
People live in risky places.
A flood plain can fill up with water and carry away the
work of generations.
Seismic hazards are issues near faults, such as the San
Andreas Fault.
It is not a good idea to live on the slopes of a an active
volcano, yet people live near Mt. Etna.
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Praxis Review for Earth Science
by Frank H. Osborne, Ph. D.
Tectonics and Internal
Earth Processes
18-22 questions
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Plate Tectonics
Plate tectonics is a unifying theory of Earth
Science.
It can explain events of the past, the present
situation, and it can predict what will happen in the
future.
•
•
•
•
Formation of mountain ranges
Continental drift and sea-floor spreading
Ocean bottom is younger than continents
Magnetic field reversals
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Plate Tectonics
• Plates move as a result of convection currents in
the mantle.
• Plates generally move about an inch or two per
year, about as fast as your fingernails grow.
• Plates can spread apart, collide or slide next to
each other.
• Plate boundaries are known for presence of
volcanoes and earthquakes.
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Plate Tectonics History & Evidence
Tectonics (from L. Latin tectonicus, from the Greek τεκτονικός "pertaining
to building") is a scientific theory that describes the
large scale motions of Earth's lithosphere, the
rigid outermost shell of a rocky planet.
On Earth, the lithosphere comprises the crust and
the portion of the upper mantle that behaves
elastically on time scales of thousands of years
or greater.
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Plate Tectonics History & Evidence
One of the main points of the theory:
The amount of surface of the (continental and oceanic) plates
that disappears in the mantle along the convergent
boundaries by subduction is more or less in
equilibrium with the new (oceanic) crust that is formed
along the divergent margins by seafloor spreading.
Just as much is cooled as gets subducted.
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Plate Tectonics History & Evidence
1596 – A. Ortelius hypothesized that continents 'drift'
1912-15 – meteorologist, A.Wegener, fully described what
he called continental drift in his book, The Origin of
Continents and Oceans
1925 – Wegener matched the continental edges of South
America and South Africa based on continent shape,
rock formations and fossil content, confirmed in 1954
1956-88 – K. Runcorn constructed apparent polar
wander paths for Europe and North America that
presume a previous plate configuration, confirmed in
1981
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Plate Tectonics History & Evidence
Snider-Pellegrini_Wegener_fossil_map.svg
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Plate Tectonics History
& Evidence
1947 - Elsasser developed geomagnetic field
theory (there are convective motions in
the fluid iron core), aka “dynamo theory”,
confirmed in 1958 by Bullard
1950’s – Many scientists measured
alternating marine magnetic polarities
≈100 ty cycles (paleomagnetism)
1968 – Mid-Atlantic ridge core
sample dating confirmed the sea
floor is spreading
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http://www.plainedgeschools.org/swells/plate_tectonics.htm
in
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Plate Boundaries (USGS)
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Plate tectonic maps and
Continental drift animations
by C. R. Scotese,PALEOMAP Project
(www.scotese.com)
Scotese, C. R., 2001. Atlas of Earth History, Volume 1,
Paleogeography,PALEOMAP Project, Arlington, Texas, 52 pp.
Click to view animation of the past 200 m.y.!
http://www.scotese.com/pangeanim.htm
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Plate Tectonics
• Divergent plates spread apart at a
spreading center. Ex: mid-Atlantic ridge
• Convergent plates are colliding.
cimss.ssec.wisc.edu
Mountain ranges will form as a result
of the collision. Ex: the Himalayas
formed by India colliding with Asia.
• Transform boundaries are found
pacificislandtravel.com
where plates slide together.
Ex: the San Andreas Fault.
San Andreas Fault offsets an orchard!
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Plate Tectonics
• Continental crust is less dense than ocean
bottom.
• At a convergent boundary between the two, the
ocean bottom is drawn under the continent. This
is called subduction.
• About 50-75 miles into the continent a line of
volcanoes will form.
• If the subducted ocean bottom is bringing lots of
water with it, the resulting steam will make the
volcanoes active.
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Plate Tectonics
•When a subduction zone is found under the ocean,
a trench forms. Ex: Puerto Rico Trench.
•A spreading center located in a continent is called
a rift valley. Ex: Great Rift Valley in East Africa.
•Sea-floor spreading moves the plates. Ex: At the
mid-Atlantic ridge, Europe and Africa are moving
away from the Americas.
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Plate Tectonics
• A hot spot is a point where a hole has been
melted through the crust from the mantle.
• The hot spot stays in one place while the crust
moves along over it. Ex: Hawaiian Island chain,
Yellowstone National Park (caldera).
• Plate activity results in earthquakes and volcanic
activity.
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Plate Tectonics
The Ring of Fire is a series of volcanoes that
surrounds the Pacific Ocean.
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Crust Deformation Processes
Extension is a stretching process. Such a
process is apparently occurring in the Basin and
Range area of the western United States.
Divergent boundaries
create rifts (on land)
and mid-ocean ridges (on the ocean floor)
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Crust Deformation Processes
Compression is a squeezing process. This is
generally associated with mountain building.
Convergent boundaries
create folds and mountains
and trenches (on the ocean floor)
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Crust Deformation Processes
Shear results from two portions of crust passing
by each other. Example is the San Andreas
fault.
Transform boundaries
create faults
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Crust Deformation Processes
• The Pacific coast mountain ranges resulted from the
collision of the North American Plate with the
Pacific Ocean Plate. Volcanoes in Washington and
Oregon indicate that there is a subduction zone
under the Pacific northwest.
• Eastern mountains in the United States were
produced by a collision between North America and
Africa. The resulting mountains were once as high
as the Himalayas; erosion from wind, water and
glacier caused the mountains to appear the way they
do today.
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Crust Deformation Processes
Western mountains in the United States display
block faulting.
It is suspected that the
continent is stretching
apart in the west. The
process of extension
causes separation of
the crust, and blocks
rubymountainphotography.com
will drop down as a result. (These are tilted.)
Similar block faulting occurred when the Atlantic Ocean began to
open. This resulted in such features as Narragansett Bay and the
Newark Basin.
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Isostasy
Isostasy refers to the fact that thicker continents
(such as Africa) ride higher on the mantle than
do thinner continents.
When large amounts of sediment are deposited on a particular
region, the immense weight of the new sediment may cause the
crust below to sink. When large amounts of material are eroded
away from a region, the land may rise to compensate.
An iceberg always floats with a certain proportion of its mass
below the surface of the water, sinking or rising to maintain that
proportion as more ice is added or removed. Likewise, the
Earth's lithosphere "floats" in the asthenosphere.
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Earthquakes and How they
Provide Information about the
Structure of the Earth
Earthquakes
• An earthquake is a sudden motion of rocks in
the crust of the Earth after a long buildup of
potential energy.
• Intensity is recorded by a seismometer on the
Richter scale which is logarithmic. This means
that a 6 is ten times stronger than a 5.
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Earthquakes
• Earthquakes are caused mostly by rupture of
geological faults, but also by other events such as
volcanic activity, landslides, mine blasts, and nuclear
tests.
• An earthquake's point of initial rupture is called
its focus or hypocenter.
• The epicenter is the point
at ground level directly
above the hypocenter.
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http://curriculum.kcdistancelearning.com/courses/ENVSCIx-AP-U10/a/unit05/apes_5.c.4.html
Seismic Wave Evidence
There are two types of seismic waves
• P waves (primary, parallel, “push”) – can
propagate through a liquid, compression type
• S waves (secondary, perpendicular, shear, slower,
“sideways”) – cannot propagate through a liquid,
longitudinal type
The precise amount that a seismic wave bends and
their velocity while traveling through Earth's interior
depend on conditions such as composition, density,
etc., in Earth's interior.
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Seismic Wave Evidence
Therefore seismic waves that have passed through
Earth's interior (from a seismic event) tell
geophysicists about the interior structure and
composition.
•The outer core of the Earth is believed to be liquid
because S waves do not pass through it and P wave
velocity is sharply decreased.
•Using similar techniques, oil companies use
seismic waves to locate bodies of liquid petroleum
under the surface of the Earth.
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Locating the Epicenter
• To locate the epicenter of an earthquake,
geologists use three seismographs in
widely separated locations.
• The time interval between the P and S
waves gives the distance of the epicenter
from the observatory. A circle with this
radius is drawn on a map or globe.
• The same is done with all three stations.
There is one point that lies on all three
circles and it is the epicenter. (This process
is called triangulation.)
Distribution of Earthquakes (geology.csupomona.edu)
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Structure of the Earth
The Earth is a series of concentric layers.
Earth_internal_structure.png
• The crust (lithosphere) is the
outer layer of the Earth.
Continental crust is light and
granitic. Ocean bottom crust is
dense and basaltic.
• The upper mantle
(asthenosphere) contains cooler
liquid rock that has very slow
convection currents, which cause
continental drift.
• The outer core is made of molten
rocks as well as iron and nickel.
• The inner core is a solid ball of
iron and nickel.
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Electricity and Magnetism
Magnets
• A magnet attracts the metals iron, cobalt and
nickel.
• A magnet has two poles called NORTH and
SOUTH.
• Opposite poles attract. Like poles repel.
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Electricity and Magnetism
Magnetic Fields
• A magnetic field surrounds a magnet.
• The lines of force emanate from the north
pole of the magnet and enter the south pole of
the magnet.
• A compass needle is an example of a magnet.
The north pole of the compass needle points
in the general direction of the geographic
north pole of the Earth.
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Electricity and Magnetism
Diagram
Photograph
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Geomagnetism
• The Earth itself has a magnetic field.
• Because the north pole of the
compass needle points north,
the North Magnetic Pole is
actually of the south type.
• The North Magnetic Pole is
11½° away from geographic north
so there is generally a compass
deviation from true north.
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Geomagnetism
Map of North Magnetic Pole
The MNP is drifting rapidly,
about 25 miles per year!
from Dr. Eowyn's Blog
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Geomagnetism
The origin of the Earth's magnetic field is not
completely understood.
It is thought to be associated with electrical
currents produced by the coupling of convective
effects and rotation in the spinning liquid
metallic outer core of iron and nickel.
This mechanism is termed the dynamo effect.
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Geomagnetism
The Earth's magnetic field shields it from
much of the solar wind.
Auroras are caused by high
energy particles from the
solar wind that are trapped
in the Earth's magnetic field;
can be visible or outside
visible spectrum
(Photograph of a visible spectrum aurora australis from earthobservatory.nasa.gov)
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Geomagnetism
As new crust is formed due to spreading, the rocks
become magnetized as they cool.
• Magnetized rocks maintain their original magnetic
orientation.
• The magnetic field of the Earth reverses occasionally,
causing bands in the magnetic orientation of the sea
floor that can be measured with a magnetometer.
• The study of this phenomenon is called
paleomagnetism.
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Praxis Review for
Earth Science
by Frank H. Osborne, Ph. D.
Earth’s Atmosphere
and Hydrosphere
18-22 question
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The Water Molecule
The Water Molecule is composed of two
atoms of hydrogen and one atom of oxygen.
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Properties of Water
• High specific heat (1 cal/g)
• Polarity--the water molecule behaves as a
dipole (having north and south) when electrified
• Density changes--maximum density is at a
temperature of only 4°C. At lower
temperatures it expands. That is why ice
floats on water. Most other substances shrink
when they freeze.
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The Water Cycle
The water cycle is also called the hydrologic cycle.
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Factors Affecting the Weather
Temperature
• Generally, air gets cooler as one rises in the
atmosphere.
• The temperature depends greatly on the amount
of insolation. (INcoming SOLar radiATION)
• The amount of insolation on the surface of the
Earth depends on latitude, altitude, season, and
time of day.
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Factors Affecting the Weather
Factors Affecting Insolation
• The higher the Sun is in the sky, the greater the
insolation.
• On a daily basis, insolation is greatest at
noontime.
• On a seasonal basis, the Sun is much higher in
the sky in the Summer than it is in the Winter. It
is higher in the tropics.
• As the Sun heats the air, it rises. Warm air is less
dense so it rises.
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Factors Affecting the Weather
The Seasons
• The seasons are caused by the inclination of the
Earth’s axis.
• Near the poles, there is very little insolation. The
air is very cold.
• In the temperate latitudes, it is cold in the Winter
but warm in the Summer.
• In the tropics, it is warm all the time.
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Factors Affecting the Weather
Time of Day
• Daily changes in insolation are called diurnal
variations.
• These result in the local daily wind patterns near
the ocean.
• During the day, the air over the land is hotter so
it rises. Cool air moves in from the ocean.
• During the evening, the air over the water is
warmer. It rises causing the air to move from the
land to the water.
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Factors Affecting the Weather
•Day and night at the shore -- sea breezes.
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Factors Affecting the Weather
Moisture
• Air contains water vapor which makes the air
humid.
• The amount of moisture the air can hold depends
on the temperature.
• Absolute humidity is the total moisture that the
air can hold at a given temperature.
• Relative humidity is the actual amount of
moisture in the air compared with the maximum
amount possible at that temperature.
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Factors Affecting the Weather
Air masses
• An air mass is a large body of air with uniform
properties of temperature, moisture and pressure.
• Continental air masses form over land.
• Maritime air masses form over water.
• If the air originated in high latitude it is called
Polar.
• If it originated in the tropics it is called Tropical.
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Factors Affecting the Weather
Air masses commonly found in the USA
•continental Polar (cP)
–cold and dry, forms over northern Canada
•continental Arctic (cA)
–very cold and dry, from arctic regions
•maritime Polar (mP)
–cold and moist, from the North Pacific region
•maritime Tropical (mT)
–warm and moist, from Gulf of Mexico
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Factors Affecting the Weather
Cold Fronts
•
•
•
A front is the boundary between two air masses of different
characteristics.
A continental Polar air mass is cold and dry.
When it moves over the Earth, its edge
is called a cold front which is
denoted by a blue line with pointy
triangles indicating the direction
of movement of the front.
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Factors Affecting the Weather
Warm Fronts
• A maritime Tropical air mass is warm and moist.
• Its edge is called a warm front and is denoted by a
red line with semicircles on it
indicating the direction of
movement.
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Factors Affecting the Weather
Stationary front
– When two distinct air masses collide, they produce
a stationary front which forms a trough between
them.
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Factors Affecting the Weather
•Absolute humidity is the amount of water vapor in
a sample of air.
•Relative humidity is the ratio of the amount of
water vapor in the air to the maximum amount of
water vapor it can hold. (Actual:Possible)
Absolute humidity is related to temperature. The
higher the temperature the more moisture the air can
hold.
When the temperature decreases, the absolute humidity
stays the same but the relative humidity increases.
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Factors Affecting the Weather
Wind
• caused by differences in insolation, which
produces global wind belts.
• air moves from areas of high pressure to areas
of low pressure.
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Factors Affecting the Weather
The Coriolis force
When air moves, the rotation of the Earth makes
it pull to the right in the northern hemisphere, to
the left in the southern hemisphere.
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Clouds
• Clouds form when moisture condenses in the
atmosphere.
• Clouds are made from tiny droplets of water
or from ice crystals.
• Saturated air will form clouds if it is cooled
below the dewpoint (saturation temperature)
of the air.
• Clouds are classified by their method of
formation and their altitude.
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Clouds
•Clouds are of basically two types, cumulus
and stratus.
•Cumulus clouds resemble balls of cotton.
They are the typical fair weather clouds.
Cumulus means “piled up”.
•Stratus clouds are low, gray and in layers.
They are associated with stationary fronts and
fog. Stratus means “covering”.
•Smog is formed from smoke and fog. It results
from the accumulation of pollutants in stagnant
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air.
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Clouds
There are three altitude levels:
• Low clouds
aka mares’ tails
(cumulo or strato, means “layer”)
•
Middle level clouds
(alto, means “high”)
•
High clouds
(cirrus, means “tuft of hair”)
–Cirrus clouds are very high, thin,
wispy clouds made of ice crystals.
•
•
Nimbus means “rain”.
Cumulonimbus clouds form
thunderstorms that reach all
three levels. They are found
along stationary fronts.
Cloud Altigram © 2011 by Suzanne Rinas Leone,(C)
Raleigh
NC
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Precipitation
Precipitation occurs when saturated air
(usually in the troposphere)
continues to be cooled, or when
warm, moist air near the
surface is carried higher
and the humidity condenses.
•Precipitation can take the
form of rain, snow, ice,
hail, or sleet, as well as
dew or frost.
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Storms
Violent storms get their energy from the heat of
fusion of water.
When water vapor condenses high in the
atmosphere, it releases 540 calories for each gram
(20 drops) of water condensed.
This is a tremendous amount of energy high in the
atmosphere where it does not belong. The result is
that the energy drives thunderstorms, tornadoes and
hurricanes.
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Development of a Storm
Weather map of a typical storm system
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Development of a Storm
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Development of a Storm
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Weather Satellites
• provide images and information to the
meteorologist
• are used in observation or current conditions,
and short-term prediction of weather.
• some are in geosynchronous orbits (the period
of revolution of the satellite around the Earth is the
same time as the Earth’s rotation, so the satellite
stays over the same part of the Earth all the time)
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Weather vs. Climate
Weather
•
•
the condition of the atmosphere and its day-to-day
changes
temperature, humidity, winds, precipitation and other
atmospheric conditions
Climate
•
•
the average of weather conditions for all the seasons
over a long period of time
temperature, moisture, latitude, nearness to large
bodies of water, and altitude
Climatic zones result from a combination of latitude,
proximity to large bodies of water, prevailing winds,
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insolation and other(C)factors.
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Mountains and Climate
The orographic effect occurs when moist air is
carried over a mountain. The windward side of
the mountain is very wet while the leeward side
is dry.
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Mountains and Climate
Views of the climate 50 miles apart
Windward--wet
Leeward--dry
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Heat Budget
The heat budget of the earth accounts for the
sources and sinks of heat on the Earth.
• Sources of heat include: solar radiation,
geothermal inputs and tides. Solar radiation
is the most important.
• Heat sinks include reflection of light and
radiation of heat from the surface. About
50% of the light striking the Earth is
absorbed. Heat energy is radiated by the
Earth back out into space. (A heat sink
absorbs and dissipates heat.)
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El Niño and La Niña
El Niño is a massive warming of the waters off
the coast of Ecuador and Peru. This warming
of the ocean causes flooding, droughts and
other weather problems in various parts of the
world. It occurs every 3-5 years.
La Niña is a period of unusually cold waters in
the tropical eastern Pacific. It occurs only
half as frequently as El Niño, and usually
lasts for 9-12 months.
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Climate Modification
• Climate is more moderate near a large body
of water. The summer high temperatures are
lower and the winter low temperatures are
higher than in the corresponding interior part
of a continent.
• Climate can be modified by mountain ranges.
This is the orographic effect.
• Climate is modified by altitude. It is colder
up in the mountains than it is at sea level.
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Human Effects on Climate
Global warming is caused in part by the
accumulation of greenhouse gases, mainly
carbon dioxide in the atmosphere.
As the greenhouse gases accumulate in the
atmosphere, they trap more heat so the global
temperature rises. This is called global
warming.
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Natural Effects on Climate
Volcanoes
•A volcanic eruption spews vast quantities of
volcanic ash high up into the atmosphere where it
may stay suspended for months or years.
•Volcanic ash in the atmosphere screens out solar
radiation resulting in a cooling effect on the Earth.
Examples:
1980 eruption of Mt. St. Helens in Washington
(see the Volcano Cam http://www.fs.fed.us/gpnf/volcanocams/msh/)
Dark Ages caused by the 535 eruption of Mt. Krakatoa in
Indonesia
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Glaciers
A glacier consists of flowing ice formed from
compacted snow.
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Ocean-Lithosphere Interactions
Estuaries
•regions which have fresh water coming in at one
and are in contact with the ocean at the other end.
•very delicate ecosystems and many contain life
forms not found in either fresh water or sea water.
•New Jersey has three estuaries. The Lower Hudson
River, Raritan Bay and Delaware Bay.
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Ocean-Lithosphere Interactions
Erosion and deposition
•Erosion is the removal of weathered rock material
by water on the surface of the land.
•The rock material is deposited in the ocean.
•As the particles settle out of the water, the heaviest
ones settle out first and are deposited close to the
shoreline.
•The lightest and smallest particles are carried by
the water much further out from the shoreline.
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Ocean-Lithosphere Interactions
Sea-level changes
• recorded over long periods of time.
• During the ice ages, the level of the ocean was
much lower than it is today. This caused erosion
in parts of the continental shelf that are now
submerged.
• An example is the formation of the Hudson
Canyon which was cut by the Hudson River
during the ice age.
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Ocean-Lithosphere Interactions
• Waves help to break up coastal rocks and
erode the shoreline.
• Tides are periodic high and low levels of the
oceans caused by the gravitational attraction
of the Moon and the Sun.
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The Ocean
• The ocean varies in temperature with depth.
It is generally about 4°C at the bottom of the
ocean.
• Salinity is a measure of the amount of salt in
the ocean. It is generally 35 parts per
thousand (35 o/oo)
• There are variations in salinity due to
introduction of fresh water and formation of
ice.
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The Ocean
• Deep ocean currents are caused by density.
• Cold water is denser (down to 4C) so it
sinks, beginning circulation of deep ocean
water.
• Warm water on the surface loses heat to the
atmosphere or radiates heat out to space.
This cools the water to enable sinking.
• Colder water is generally saltier because
when water freezes, the salt remains behind
in the liquid water.
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Praxis Review for
Earth Science
By
Frank H. Osborne, Ph. D.
History of the Earth
and its Life Forms
13-17 questions
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Uniformitarianism
The assumption that the geological process that
we see taking place today have always been at
work, and were at work in the past.
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Stratigraphic Correlation
Original horizontality
•
based on the observation that when sedimentary particles
settle out of the water, they are under the influence of
gravity and form horizontal beds
Superposition
•
in undisturbed layers of rock, the oldest layer will be found
at the bottom and the youngest layer will be found on the
top.
Lateral Continuity
•
sediment extends laterally in all directions until it thins out
or terminates against the edge of the depositional basin
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Stratigraphic Correlation
Example: Grand Canyon
•The sedimentary rocks of the Grand Canyon were
originally deposited horizontally under the water or
in a coastal environment (principle of original
horizontality).
•The oldest rocks are at the bottom and the youngest
are at the top (principle of superposition)
•The exposed rocks extend in all directions and can
be shown to be in the north and south walls
(principle of lateral continuity).
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Stratigraphic Correlation
Cross-cutting relationships
• used to determine the relative ages of events.
• An igneous intrusion or a fault must be younger
that the rocks it intrudes or cuts.
Index fossils
• used to indicate rock layers in different places
that are part of the same formation
• Rock layers of a given age will generally contain
the same forms of index fossils
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Unconformity
• a point in the geological record where strata are missing.
• a discontinuity consisting of an erosion surface
between younger strata and older rocks.
Nonconformity
Examples:
Disconformity
Angular Unconformity
http://www.cliffsnotes.com/study_guide/topic
ArticleId-9605,articleId-9497.html
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The Fossil Record
Fossils
• A fossil is the remains of something that was
alive or was made by something that was
alive.
• The object becomes a fossil as a result of a
sequence of steps.
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The Fossil Record
Types of fossils
• Organic remains may create a depression or mold
which later fills in to become a cast.
• Some fossils are made by mineral substitution in
the sediments.
• Imprints are impressions made in the sediments
by the object.
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The Fossil Record
• Before the discovery of radioactivity, geologists did
not know the age of rocks. So they used index
fossils.
• Certain kinds of fossils can be used to correlate
layers of rocks in different locations.
• Radioactive dating of rocks involves Uranium-238.
It has a very long half-life which is 4.5 x 109 (4.5
billion) years.
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Paleontology
Paleontology is the study of fossils.
• Using fossils, geological time sequences and
fossil positions in the geological record, it is
possible to construct a sequence of the
development of life on Earth.
• Mass extinctions have occurred at several
important points in the fossil record. The
most recent is the K-T boundary at 65 million
years ago.
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How a fossil is formed
• An animal dies and decays. Only the bones
remain.
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How a fossil is formed
• The bones are covered by sediments under
water.
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How a fossil is formed
• Over many years the layers of sediments
above the bones increase.
• The sediments become sedimentary rock.
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How a fossil is formed
• The molecules of the bones are slowly
replaced by minerals. Bone turns to stone.
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How a fossil is formed
• After some time, uplift causes the rocks to be
lifted above sea level.
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How a fossil is formed
• Erosion washes the rocks away and exposes
the fossil.
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Geologic Time Scale
•Geologic time is
divided into eras,
periods and epochs.
•Mainly the
distinctions are based
on fossil evidence.
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Age and Dating
•Absolute age tells how old something is as
compared with the age of the Earth.
•In some cases rocks must be compared with
each other so only the relative age is known.
•Radioactive dating employs measurements of
radioactive nuclei that decay at known rates.
For example, U-238 decays into Pb-206 at a
known rate that can be measured in rocks,
thereby providing their ages.
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Paleogeography
The continents have not always been in the
same locations.
Plate tectonic forces have been at work throughout
most of the history of the Earth.
There is evidence that North America used to be
located on the Equator and Africa used to be located
on the South Pole.
In this case, North America would have been tropical
and Africa, frozen.
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Paleogeography
• Fitting the continents together
– Try cutting the map to fit the Americas and Africa
together. We think it looked like this 200 million
years ago.
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Praxis Review for
Earth Science
By
Frank H. Osborne, Ph. D.
Astronomy
8-12 questions
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Astronomy
• the study of the positions, movements and
structure of celestial objects.
• includes: Sun, Moon, planets, satellites,
asteroids, meteors, comets, and stars
• includes: the motions of the Earth as it travels
through space
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Astronomy
The Earth
• the third planet in the solar system (counting from
the Sun)
• approximately 93,000,000 miles from the Sun
• diameter of 7918 miles
• Nearly 3/4 of the surface of Earth is covered by
water
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Astronomy
Motions of the Earth - Revolution
• The Earth revolves around the Sun.
• One complete revolution of the Earth around the
Sun takes one year.
• Because of this, the patterns of the stars change
during the seasons.
• The stars themselves actually move (proper motion)
but they are so far away it takes thousands of years
to notice any difference in the star patterns.
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Astronomy
Motions of the Earth - Rotation
• The Earth rotates on its axis.
• One complete rotation takes one day.
• The Earth rotates from west to east. This is why the
stars rise in the east and set in the west.
• Viewed from above the North Pole, the Earth rotates
counterclockwise.
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The Seasons
• Like the stars, the Sun appears to move from east
to west every day.
• The axis of the Earth is inclined 23½° from the
vertical. The vertical is the line perpendicular to
the orbital plane of the Earth.
• This inclination causes the Sun to be found at
different altitudes in the sky at different times of
the year.
– Highest point is on June 21—southern solstice
– Lowest point is (C)
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December
21—northern
solstice
Frank Osborne
PhD
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The Seasons
Position of the Earth in different Seasons
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The Seasons
Summer
• On the “first” day of Summer the Sun is directly
overhead on the Tropic of Cancer.
• The Sun is at its maximum altitude in the sky in
the northern hemisphere and it is the longest
length of daylight.
• This day is June 21, the Southern Solstice.
• During the next three months, the Earth moves
1/4 of the way around its orbit.
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The Seasons
Autumn
• On the “first” day of Autumn the Sun is directly
overhead on the Equator.
• The day and night are of equal length in all parts
of the world.
• This day is September 21, the Fall Equinox.
• During the next three months, the Earth moves
another 1/4 of the way around its orbit.
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The Seasons
Winter
• On the “first” day of Winter the Sun is directly
overhead on the Tropic of Capricorn.
• It is the shortest length of daylight in the
northern hemisphere and the Sun is at its lowest
altitude.
• This day is December 21, the Northern Solstice.
• During the next three months, the Earth moves
another 1/4 of the way around its orbit.
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The Seasons
Spring
• On the “first” day of Spring the Sun is directly
overhead on the Equator.
• The day and night are of equal length in all parts
of the world.
• This day is March 21, the Spring (Vernal)
Equinox.
• During the next three months, the Earth moves
the final 1/4 of the way around its orbit.
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The Seasons
Length of Daylight
• Varies from day to day
• Varies from place to place.
• This variation is due to the inclination of the
Earth’s axis and the revolution of the Earth
around the Sun.
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Time Zones
Time Zones
• Time zones were developed to standardize time
around the world.
• The International Date Line was positioned in a
relatively unpopulated part of the Pacific Ocean.
• A person travelling west across this line has to
advance their calendar by one day.
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The Moon
• The Moon is the only natural satellite of Earth.
• The Moon revolves around the Earth from west to
east. One orbit takes 29½ days.
• The Moon has a captured rotation. This means
that it rotates once per orbit. The result is that the
same face is always pointing toward the Earth.
• Every month the Moon comes close to the Earth
(perigee) and then gets further away from the
Earth (apogee).
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Phases of the Moon
The Lunar Cycle
• As the Moon revolves around the Earth, the angle
of the sunlight hitting the Moon appears to
change as observed from the Earth.
• As we view the Moon during every lunar cycle
and the angle changes, the Moon appears to pass
through its phases.
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Phases of the Moon
• The lunar month begins at New Moon when only
the shadowed side of the Moon is facing Earth.
• After about 3 days a thin crescent is seen at
sunset in the west.
• The lit part of the Moon always points toward the
Sun.
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Phases of the Moon
• The crescent Moon gets higher in the sky (further
east) and thicker every day for2 weeks.
• This is called waxing.
Day 3
Day 5
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Day 7
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Phases of the Moon
• First Quarter occurs at 1 week when the Moon is
one-quarter of the way around its orbit.
• It is in the south at sunset with the lit side
pointing west.
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Phases of the Moon
• Full Moon occurs when the Moon is on the
opposite side of the Earth from the Sun.
• At Full Moon, the Moon rises in the east just as
the Sun is setting in the west.
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Phases of the Moon
• On the days following Full Moon the Moon rises
progressively later and becomes progressively
thinner.
• This is called waning.
Day 15
Day 18
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Day 22
163
Phases of the Moon
• Last Quarter is when the Moon is 3/4 of the way
around its orbit.
• The Moon is seen in the south at sunrise with the
lit side pointing east (toward the Sun as always).
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Phases of the Moon
• After Last Quarter the Moon continues waning
through progressively thinner crescents.
• Crescent Moon is seen in the east just before
sunrise.
• After that, New Moon begins another cycle.
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Eclipses
Eclipses are products of the Earth-Moon-Sun
system.
• The orbit of the Moon is tipped at an angle of 5°
to the plane of the Earth’s orbit.
• For this reason, eclipses do not occur every
month.
• Eclipses cannot be seen from all points on Earth
at the same time.
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Eclipses
Eclipse of the Sun (Solar eclipse)
• Eclipse of the Sun occurs at New Moon time.
• The Moon passes in front of the Sun and blocks it
out.
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Eclipses
Eclipse of the Moon (Lunar eclipse)
• Eclipse of the Moon occurs at Full Moon time.
• The Moon passes through Earth’s shadow and
darkens temporarily.
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Astronomical Basis for Tides
• Water on Earth is closer to the Moon than the
center of the Earth is. (Radius of Earth is 6378
kilometers.)
• Moon’s gravity attracts water closest to it so the
water accelerates toward the Moon.
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Astronomical Basis for Tides
• Likewise, the center of the Earth is closer to the
Moon than the water on the opposite side so the
Earth accelerates toward the Moon a little.
• The result of the attractions by the Moon is the
production of two tidal bulges one on each side of
the Earth.
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Astronomical Basis for Tides
• As the Moon revolves around the Earth the tidal
bulges follow it.
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Planets
• Planets are celestial bodies that revolve
around the Sun. They are major components
of the Solar System.
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Planets
How the planets differ
• Mercury, Venus, Earth and Mars are small
and rocky. These are known as the terrestrial
planets because they resemble Earth.
• Jupiter, Saturn, Uranus and Neptune are
large and gaseous. They are known as the
Jovian planets because they resemble Jupiter.
They are also called the gas giants.
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Planets
Dwarf Planet Criteria
Ceres, Pluto, Haumea, Makemake, and Eris
(plus 50-200 more still to be classified!)
• Orbits the Sun (possibly after the formation of the
solar system)
• Has sufficient mass to assume a nearly round shape
• Is not a satellite of a planet
• Has not “cleared the neighborhood” around its orbit
(become gravitationally dominant)
http://www.iau.org/static/resolutions/Resolution_GA26-5-6.pdf
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Planets
Planets change their position in the sky as seen from
Earth against the background of stars because the
planets are much closer to Earth than the
background stars are.
The planets orbit the Sun at different rates, therefore
their positions in the sky constantly change.
As Earth passes by a slower planet (one whose orbit
is further out) the planet seems to be moving
backward for a time. This is called retrograde
motion.
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Sizes of the Planets
Assume Earth has a mass of 1.00. The relative
masses of the planets are as follows:
Mercury (0.06)
Saturn (95.16)
Venus (0.82)
Uranus (14.50)
Mars (0.11)
Neptune (17.20)
Jupiter (317.83)
In comparison, the mass of the Moon is 0.012, the
mass of Pluto is 0.0025, and the mass of the Sun
is 332, 946.0
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Orbits in the Solar System
Other elements of the solar system
• Asteroids are smaller bodies that orbit the Sun
in the Asteroid Belt. The Asteroid Belt is
located between the orbits of Mars and Jupiter.
• A comet is a solar system object whose orbit
forms an arc near the Sun. Comets are
recurrent, meaning that they return periodically.
They are made of frozen gases and solid
particles making them like “dirty snowballs.”
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Orbits in the Solar System
Other elements of the solar system
• Meteoroids are small particles which orbit the
Sun. When they enter the atmosphere they burn
up forming meteors, which are the streaks of
light. If a solid object makes it all the way to
the ground it is a meteorite.
• Planetary orbits in the Sol system (ours) orbit
Sol, are generally elliptical, and are in the same
plane.
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Orbits in the Solar System
Kepler’s Laws of Planetary Motion
• The orbit of a planet is an ellipse
with the Sun at one of the two foci.
• As a planet revolves around the Sun it sweeps
out arcs of equal areas in equal times.
• The square of the sidereal period (the time it takes an
object to make one full orbit, relative to the stars) of a
planet is proportional to the cube of the semi-major
axis of its orbit (an ellipse's long radius). SP2 :: SMA3
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The Stellar System
Stars twinkle because they are so far away that
the light appears as a point.
Planets have a measurable diameter in the sky
because they are closer so they don’t twinkle.
Stars are organized into groups called
constellations. Different constellations are seen
during different seasons because the Earth
revolves around the Sun. Over the year,
therefore, there are changes.
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The Stellar System
Temperature and color
• Stars are categorized according to color
(temperature).
• As the colors proceed across the spectrum from
red toward blue, the temperatures of stars
increase.
• Color of a star and surface temperature of stars
are related.
• Dark line spectra result from absorption of light
by cooler gases at the surface of the star.
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The Stellar System
Brightness
• The brightness of a star is its magnitude.
• The brightness as seen from Earth is called the
apparent or visual magnitude.
• Some stars are further away but give off more
light. Therefore, we can speak of the real
amount of light given off which is the absolute
magnitude.
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The Stellar System
Life Cycle of Stars
• Stars form by condensation of vast quantities of
gas and dust.
• When they achieve sufficient mass, they ignite
nuclear reactions which give off light, heat and
other radiation.
• When they run out of hydrogen, they begin to
fuse other elements until they are used up. They
then become red giants.
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The Stellar System
Life Cycle of Stars, continued
Red giants eventually collapse and become white
dwarf start which are about the size of the Earth.
Some really massive stars explode violently to
cause a supernova. The nuclear reactions
involved in the explosion create all of the
elements in the periodic table.
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The Stellar System
Life Cycle of Stars, continued
Sometimes the collapse of a star causes all of the
mass to become concentrated in one small
object (about 5 - 15 km in radius, but with
tremendous mass) . This produces a neutron
star.
Larger such masses produce black holes. The
gravity in a black hole is so great that not even
light can escape.
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The Stellar System
Life Cycle of Stars, continued
Sometimes the collapse of a star causes all of the
mass to become concentrated in one small
object (about 5 - 15 km in radius but with
tremendous mass) . This produces a neutron
star.
Larger such masses produce black holes. The
gravity in a black hole is so great that not even
light can escape.
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The Stellar System
Hertzprung-Russell Diagram
A Hertzprung-Russell diagram plots absolute
magnitude against color (temperature).
Most stars fall along a line which is known as the
main sequence, meaning they are fusing
hydrogen into helium. Various
stars in different stages of
development fall on this line,
so the line gives an indication
of the life cycle of stars.
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The Stellar System
Composition of stars
Stars are made of vast quantities of gas, usually
hydrogen, that fuses into helium producing
energy.
Different elements in stars give off different
spectra which can be duplicated in the
laboratory. The spectrum of a star can be
analyzed to determine the composition of the
star.
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The Stellar System
Distances in the Universe
Light travels at a speed of 300,000 km/sec or
186,000 miles/sec.
At this rate, light will travel 5.87 x 1012 miles in
one year. This distance is known as a lightyear.
The parsec is the distance away of a star that
would have a parallax angle of one second. A
parsec is about 3.09 x 1016 meters, or 3.262
lightyears.
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The Stellar System
Parallax is the apparent shift in locations of an
object when it is viewed from two different
positions.
Nearby stars display parallax when compared to distant
stars which allows their distances from Earth to be
calculated by triangulation.
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The Stellar System
Cepheid variables are luminous giant stars whose
luminosity varies in a periodic fashion (a rapid
rise in luminosity that is followed by a slow
decline).
The more luminous ones have longer periods.
The periodicity and luminosity relationship allows
distances to be calculated in the universe.
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Galaxies
A galaxy is a vast number of stars rotating about a
black hole which forms the center of the galaxy.
There are also galaxy clusters which contain
groups of galaxies that are gravitationally bound
to each other.
The Sol system is located in the Milky Way
Galaxy.
All stars that can be seen individually from Earth
are part of the Milky Way galaxy.
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Telescopes
Telescopes are used to view distant objects.
Refractors are telescopes with lenses that bend the
light and create a magnified image of the object.
These lenses are looked through directly.
Reflectors collect light using a mirror. The light is
then passed through a lens for viewing.
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Telescopes
Hubble Space Telescope
Telescopes on the ground all have to view objects
in space through the Earth’s atmosphere which
causes distortion and absorption problems.
The Hubble Space telescope is in orbit above the
atmosphere and therefore can “see” better than
any telescope on Earth.
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Satellites and Instruments
Humans can extend their senses by attaching
detectors to satellites.
Space probes are used to detect electromagnetic
radiation, dust and other things of interest to
scientists.
Recent landings on Mars have extended the
senses of the geologist who can probe Martian
rocks and other objects via satellite.
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Satellites and Instruments
The International Space Station may someday
be a staging area for human exploration of the
solar system.
Humans have already landed on the Moon.
The Space Station can also permit scientists to
perform experiments in space under zerogravity conditions.
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Satellites and Instruments
Computers are used for data analysis and storage
of information obtained from satellites.
Some satellites have been sending back prodigious
amounts of information that will be keeping
scientists busy for years. One such was the
Infrared Telescope that was sent up in and
operated in the 1990s.
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The Universe
The Universe is thought to have begun with a “big
bang” over 15 billion years ago.
Evidence for this is that the furthest objects in the
Universe are moving away at the fastest rates.
Because these objects are so far away, the light
that we see today left them billions and billions
of years ago.
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Other Objects of the Universe
A quasar is a quasi-stellar object. These give out radio
waves. Quasars are moving away among the fastest
objects in the Universe.
A pulsar is produced when a star explodes. The explosion
produces heavy elements and changes much of the mass
of the star to energy. The explosion is called a supernova.
After the supernova, the remains of the star forms a
neutron star. These are very dense and rotate very
rapidly--so rapidly that they pulsate.
A black hole results from a supernova with a large enough
remnant that no light escapes from its gravitational pull.
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Praxis Review for
Earth Science
By
Frank H. Osborne, Ph. D.
Basic Principles of Earth and
Space Sciences
8-12 questions
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Earth Science in NC
“The Earth/Environmental science
curriculum focuses on the function of Earth's
systems. Emphasis is placed on matter,
energy, plate tectonics, origin and evolution of
the earth and solar system, environmental
awareness, materials availability, and the
cycles that circulate energy and material
through the earth system.” (NC SCOS, 2004)
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Humans & Energy
Humans use various sources for production and
use of energy.
• These include fossil fuels (coal, oil, natural gas),
nuclear, geothermal, hydroelectric, and solar.
• Most are non-renewable. Anything dug out of
the ground will eventually run out.
Teachers should be aware of the issues
surrounding these sources of energy, and the
points of discussion over each.
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Energy & the
Electromagnetic Spectrum
Electromagnetic energy is found in waves.
• The energy is indicated by the wavelength.
The shortest waves have the most energy
while the longest waves have the least
energy.
• The electromagnetic spectrum is logarithmic.
This means that each unit is a factor of 10
(10 times larger or smaller than the unit next to it).
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Energy in Earth Systems
Earth has external and internal sources of
energy in the form of heat.
• external = the Sun.
• internal =
Radioactive decay
Gravitational energy resulting from the
Earth’s mass
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Energy in Earth Systems
Heat escapes slowly from Earth’s core.
• The transfer of heat from within the Earth produces
convection currents in the mantle.
• The convection currents of the mantle cause movement
of the tectonic plates of the crust as the mantle carries
them along with it.
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Energy in Earth Systems
Insolation means Incoming Solar Radiation
Heating by the Sun causes convection currents
in the atmosphere and the oceans.
• Convection in the atmosphere causes the
global wind patterns and belts.
• Convection in the ocean results in the global
pattern of ocean currents.
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Energy in Earth Systems
Wind is caused by uneven insolation.
• The differential heating
of the atmosphere
produces global
wind belts.
• In our latitudes, the
predominant wind direction
is from the west. At the poles and also in the tropics,
the winds blow from the east.
• Air moves from areas of high pressure to areas of low
pressure, seeking to create equilibrium.
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Energy in Earth Systems
Convection currents in the oceans result in
ocean currents.
• Deep ocean currents are driven by gravity.
The densest water sinks causing convection
currents in the ocean.
• As warm water currents release their heat to
the atmosphere, they sink.
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Insolation and Climate
The higher the Sun is in the sky, the greater
the insolation.
• On a daily basis, insolation is greatest at
noontime.
• On a seasonal basis, the Sun is much higher
in the sky in the Summer than it is in the
Winter. It is higher in the tropics.
• As the Sun heats the air, it rises. Warm air is
less dense so it rises.
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Insolation and Climate
The Seasons
• The seasons are caused by the inclination of
the Earth’s axis.
• Near the poles, there is very little insolation.
The air is very cold.
• In the temperate latitudes, it is cold in the
Winter but warm in the Summer.
• In the tropics, it is warm all the time.
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Laws of Thermodynamics
Thermodynamics describes how systems change
when they interact with one another or with their
surroundings.
Zeroth Law: If two systems are each in thermal
equilibrium with a third, they are also in
thermal equilibrium with each other.
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Laws of Thermodynamics
First Law: The amount of energy in a system
stays the same. (obeys Conservation of
energy).
Second Law: Heat never flows from a cold
substance to a hot substance, only toward
complete entropy (disconnection within a
system).
Third Law: No system can reach absolute zero,
or complete entropy.
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Heat vs. Temperature
Heat and temperature
• Heat is a form of electromagnetic energy.
• Temperature is the average kinetic energy of
the particles in the substance. If the
substance gets hotter (more energy), the
kinetic energy of the particles increases and
the temperature rises.
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Transfer of Heat
Heat can be transferred in three ways.
•Conduction is transfer of heat by direct contact.
•Convection is transfer of heat via currents of water
or air.
•Radiation is transfer of heat via electromagnetic
radiation.
Heat is always transferred from hotter to
colder.
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Transfer of Heat
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Greenhouse Effect
Clear glass (or gas) can act as a mirror for
certain wavelengths and transmit others.
• In a greenhouse, light passes through the glass.
Once inside, it is absorbed and re-emitted as
heat. The greenhouse heats up because heat
will not pass through glass.
• “Greenhouse gases” such as CO2 are suspected
of causing the same effect in the atmosphere
resulting in global warming.
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Atomic Structure
Structure of the Atom
•The nucleus is made of protons and neutrons.
•The electrons travel in orbits (valence shells)
around the nucleus.
•Atomic number = number of protons.
•Atomic mass = number of protons + neutrons.
(Find the number of neutrons by subtraction.)
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Structure & Properties of Matter
•Matter is made of elements.
•Matter exists as a solid, liquid or gas.
•Matter can change phase (or state) by
absorbing or releasing heat.
•Melting is the change from solid to liquid. For
water, the heat of fusion is 80 cal/g.
•Boiling is the change from liquid to gas. For
water the heat of vaporization is 540 cal/g.
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Structure & Properties of Matter
•Matter has various physical and chemical
properties. These include:
–melting point, boiling point, color, density
–combustibility, oxidation potential, reactivity
•Matter is organized in the form of elements and
compounds.
•Different compounds can form mixtures and
solutions, or they can react to form different
substances.
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Structure & Properties of Matter
•An element is a substance that cannot be decomposed by
ordinary means.
•Each element has its own atomic structure.
•There are over 100 elements.
• The Periodic Table of the Elements which arranges
the elements by properties.
• In the Earth’s crust:– Oxygen is 93.8% by volume
– Oxygen and Silicon are 74.3% by mass
– The remaining abundant elements by mass are Al, Fe,
Ca, Na, K and Mg.
TheFrankrest
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Structure & Properties of Matter
Periodic Table of the Elements
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Nuclear Reactions
Radioactivity is a property of atoms that have an
unstable nucleus.
There are three major types of radiation
produced.
• Alpha (a) radiation--the nucleus emits a nucleus
of helium.
• Beta (b) radiation--the nucleus emits an electron.
• Gamma (g) radiation--the nucleus emits very
powerful electromagnetic radiation.
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Isotopes
Isotopes are atoms with the same atomic number
(protons) but different atomic masses (neutrons).
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Half-life
Half-life is the length of time necessary for half
of a given quantity of radioactive nuclei to decay.
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Nuclear Fission
Nuclear fission occurs when a large, unstable
nucleus is broken apart. Some of the binding
energy is released.
–1. A slow neutron is captured by U-235 which
becomes U-236 which is unstable.
–2. The U-235 nucleus splits releasing two smaller
nuclei and some neutrons. Sometimes one of these
is I-131.
–3. The neutrons can become captured by other
nuclei of U-235 causing a chain reaction.
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Nuclear Fission
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Nuclear Reactors
A nuclear reactor contains a controlled
nuclear fission chain reaction.
• The controlled reaction occurs at a constant rate.
• The heat released from the reaction is used to
boil water to make steam.
• The steam is used to produce electricity by
driving turbines.
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Nuclear Reactors
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Nuclear Fusion
Nuclear fusion occurs when small nuclei are
forced together.
• Nuclear fusion occurs in the Sun and is
known as thermonuclear energy. It is the
same as is released in the hydrogen bomb,
which is uncontrolled.
• On Earth, the fusion reaction has not been
controlled.
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Nuclear Fusion
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Nuclear Fusion
Mass can be converted to energy in nuclear
reactions.
•The relationship between mass and energy was
derived in Einstein’s theory of relativity.
•In this equation, E is the energy, m is the mass
and c is the speed of light.
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Fundamental Processes
•
•
•
•
•
Evolution
Repetitive Cycles
Biogeochemical Nutrient Cycles
Chemical reactions
Gravity
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Fundamental Processes
Evolution
• the theory used to explain the origin of
different species of living creatures.
• involves accumulation of biological changes
over time.
• Fossils provide evidence of creatures that
lived in the past but are extinct today.
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Fundamental Processes
Biogeochemical cycles
The environment contains numerous cycles
which are used to circulate nutrients in the
ecosystem.
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Fundamental Processes
Cyclic change
• Natural cycles repeat themselves
Motion of celestial objects
Changes in the seasons
The Rock Cycle
The Water Cycle
• Many changes can be measured so they can
be predicted, ex: solar and lunar eclipses.
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Fundamental Processes
Chemical reactions
• Many different substances can react with
each other to produce new substances.
• Chemical reactions are one of the causes of
weathering of rocks and contribute to erosion.
• Acid precipitation in the form of rain, snow
and other forms accelerates erosion of certain
rocks, such as limestone.
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Fundamental Processes
Gravity
• Gravity is the attraction of objects by the
Earth’s mass.
• Gravitational energy is one source of the heat
inside the Earth.
• Gravity is involved in erosion and also must
always be considered in the space sciences.
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Waves
Types of waves
•Transverse waves cause the particles of the
medium to vibrate at right angles
(perpendicular) to the direction in which the
wave is moving. Example: a wave made by
shaking a rope.
•Longitudinal (compression) waves cause the
particles of the medium to vibrate parallel to
the direction in which the wave is moving.
Example: squeezing a section of a slinky toy.
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Waves
•Transverse waves
•Longitudinal (compression) waves
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Waves
Water waves
Water waves are of the transverse type. The
wind provides the energy for water waves.
Size of the wave is determined by:
•Speed of the wind
•How long it blows
•How far the wind travels
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Waves
Earthquake (seismic) waves
There are two types of earthquake waves:
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Praxis Review for
Earth Science
By
Frank H. Osborne, Ph. D.
History & Nature of Science
0-5 questions
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The Scientific Method
The Scientific Method has several steps:
•A natural phenomenon is observed
•A hypothesis (proposed explanation) is made
•An experiment is performed
•Results are obtained
•The hypothesis is supported or disproved
•Any scientific explanation is called a theory
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The Nature of Science
•Science is based on observations and
measurements, not on belief or dogma.
•We learn in science, not by proving
something true, but by proving something
else to be false.
•All scientific knowledge is tentative.
•There is not just one method.
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The Nature of Science
•Scientific knowledge is consistent with
evidence, subject to change and open to
criticism.
•Models are used to help study natural things
and processes.
•Science has many disciplines but the
knowledge forms a unified whole.
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The History of Science
Some major figures in science:
•Curie
•Mendel-genetics
•Darwin-evolution
•Galileo-heliocentric astronomy
•Hutton
•Mendeleev
•Einstein-physics
•Dalton
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The History of Science
Some major events in science:
•DNA structure
•Big bang theory
•Atomic imaging
•Light bending in gravitational fields
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The Metric System
The Metric System is used for measurement.
•Length is measured in units of the meter.
•Volume is measured in units of the liter.
•Mass is measured in units of kilograms.
•Time is measured in units of seconds.
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The Metric System
Prefixes used in the Metric System
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Processes of Science
•Scientific data collection
•Analysis and interpretation using charts and
graphs
•Data manipulation
•Presentation
•Critical analysis of sources of data
•Analysis of errors using statistics and error
procedures
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Laboratory Safety and Procedures
•Scientists need to know and understand the
rules, regulations, policies and procedures
involving laboratory and field materials.
•This includes the preparation, use, handling,
storage and disposal of chemicals and
biological materials.
•Scientists should be able to identify, use and
maintain science equipment and apparatus
properly in the lab and field.
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Laboratory Safety and Procedures
•Special precautions are necessary for
handling, use, storage and disposal of acids,
bases, toxic materials, microbiological
samples, as well as materials that are health
and fire hazards.
•Scientists should be able to prepare reagents,
materials, and equipment setups properly for
laboratory and classroom use. They should
also understand and follow humane
treatment procedures for living organisms.
253
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Laboratory Safety and Procedures
•Teachers should know and understand the
legal responsibilities associated with safety
and emergency procedures for the science
classroom and laboratory.
•This includes understanding and compliance
with all rules, regulations, policies and
procedures regarding classroom and
laboratory safety.
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Equipment
•Teachers should know and understand the
appropriate use of equipment and
instruments for making measurements and
observations in the Earth Sciences.
•This includes use of computers and related
technologies as they apply to scientific
investigation.
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