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Earth
Formation of the
Solar System
The Nebular
Hypothesis is the
most widely
accepted model
of the formation
of our solar
system.
Nebular
Hypothesis
About 4.6 bya
a great cloud
of gas and
dust was
rotating slowly
in space.
Forces of gravity
caused the cloud
to begin to shrink.
As the size of the
cloud shrank the
rotation increased.
90% of the
material rotating
in the cloud
began to gather
around the
center and this
compression of
material made
the interior so
hot that
hydrogen fusion
occurred.
The fusion
formed a star
(our sun).
The remaining
10% of material in
the cloud formed a
plate-like disk
which surrounded
the sun.
The mass and
material within the
disks formed solid
patches of ice and
rock – eventually
forming our
planets, which
orbit our sun.
(solar system)
Earth is the 3rd
planet from the
sun.
Approximately
71% of Earth is
covered with water
and 29% is
covered with dry
land.
Earth has 4 main layers:
•Inner Core
•Outer Core
•Mantle
•Crust
And the
Lithosphere (the
plates) and
Asthenosphere
(molten material
plates move on)
Some of the heat that caused
Earth’s layers came from
meteor impacts over 4 billion
year ago, from decay of
radioactive isotopes
(elements releasing heat as
they disintegrate into more
stable forms), and from
weight of overlying materials
that caused compression in
Earth’s interior.
Now Earth is slowly losing heat because: some
rocks lose heat more quickly than others, the
thickness of the crustal rock varies from place to
place, and the percentage of radioactive materials
in rocks varies.
Earth’s Rotation
Earth is tilted on its axis about
23.5º and moves in a
counterclockwise direction.
(This gives the appearance the
sun rises in the east and sets in
the west).
Earth rotates (completes one
turn on its axis) 360º about
every 24 hours = our days and
nights.
In the Northern Hemisphere,
Earth’s axis points towards Polaris
(the North Star).
Evidence and effects of Earth’s
rotation are:
Foucault’s pendelum and the Coriolis Effect.
• Jean Foucault’s Pendelum –
(moving about 11º in a clockwise
direction each hour)
• The Coriolis Effect - (winds appear to turn
or be deflected to the right in the Northern
Hemisphere and to the left in the
Southern Hemisphere).
Evidence and effects of Earth’s
rotation are:
Earth’s Revolution
Earth rotates and revolves in a
counterclockwise direction.
Earth makes one revolution
(one orbit) around the sun every
365.24 days = about 1 year.
Evidence for Earth’s revolution was the
appearance that stars were shifting positions in the
sky.
This
appearance of
stars shifting
in the sky is
called
parallax.
The Earth’s orbit is an ellipse, or elliptical,
therefore, there are times when Earth is closer to
the sun and times when its further from the sun.
Periphelion is when Earth is closest to the sun.
Aphelion is when Earth is furthest from the sun.
Earth’s tilt causes the seasons on Earth.
Seasons and variations in the length of days and
nights are effects of the Earth’s revolution and tilt.
The hemisphere tilted towards the sun receives
more direct sunlight, so that hemisphere has
warmer temperatures and longer days.
(Therefore, the
hemisphere tilted away
from the sun receives
indirect sunlight, so
that hemisphere has
cooler temperatures
and shorter days).
The Summer Solstice is June 21st and it is the 1st
day of summer in the Northern Hemisphere
(N.Hemi at its maximum tilt towards sun).
Because we tilt 23.5º, the sun is straight overhead
at locations along the 23.5º N latitude line (Tropic
of Cancer). Areas above the 66.5º N latitude
(Arctic Circle) experience 24 hours of daylight.
The Winter Solstice is December 21st and
it is the shortest day of the year in the
Northern Hemisphere (N.Hemi at its
maximum tilt away from the sun).
The Vernal Equinox is on March 21st
The Autumnal Equinox is on
September 22nd.
Day and night are equal in length all
over the world on these dates.
Sunlight falls directly on the equator
(so day and night are equal because
neither hemisphere tilts toward the
sun).
Earth Moon and Sun RelationshipsMake the tides and eclipses.
•Spring Tide is a especially high tide and especially low
tides. It occurs at the full or new moon phase (so occur
twice a month). The sun and moon are aligned with the
Earth.
•Neap Tide occurs at the 1st or last quarter moon phase (so
occurs twice a month). The sun and moon are pulling at 90
degree angles to each other, so there is hardly any change
between the high and low tides.
What do winds and ocean currents
and evidence for Earth’s rotation all
have in common???
Coriolis Effect Link
Apparent curving of moving
objects (ie- Water or winds) due to
the Earth’s rotation
To the right (clockwise)
in the Northern
Hemisphere
To the left
(counterclockwise) in the
Southern Hemisphere
Surface Current Link
Controlled by three factors
• Global winds
• Coriolis Effect
• Continental Deflections
Warm currents move from
the equator toward the poles
Cold currents move from the
poles to the equator
Deep Thought Oceanography Questions from Ch. 22:
1.What elements make up a water molecule and how are they
arranged?
2.How much of Earth’s surface to oceans cover?
3.Why does ice float on top of water?
4.Why do people float in the Dead Sea?
5.Is there salt in icebergs?
6.What happens to the salt when water freezes?
7. How does salt get into oceans?
8.Does seawater freeze at 32ºF (0ºC)?
9.Why are there different temperature zones in the oceans?
10.Name a few things that are found in deep ocean life?
11.Would ocean salinity be lower or greater in areas of
heavy rainfall and areas where large amounts of fresh water
enter the ocean?
Deep Thought Oceanography Questions from Ch. 22:
http://www.earthscape.org/t2/meg01/meg01c.html#margin
Ocean Floor
Name the Bathymetric (Sea
Floor) Features
Oceanography Questions from Ch. 24:
1.Currents flowing away from the warm equator carry
(A. warm B. cold) water, and currents flowing toward the
equator come from the poles and carry (A. warm B. cold)
water.
2.Gulf Stream carries warm water that originates and ends
where?
3.What is the primary cause of surface currents?
4.Why is Labrador Current hazardous to ships going from
Europe to North America?
Oceanography Questions from Ch. 24:
1.What causes tides?
2.What is a high tide?
3.What is a low tide?
4.How are spring and neap tides different from high and low
tides?
5.Why do tides occur 50 minutes later each day?
6.Draw the position of the sun, moon, and earth during a spring
and neap tides.
Freshwater & GroundwaterA river and its tributaries (other streams and
rivers that flow into the main river) make up
the River System.
Drainage Basin/Watershed - consists
of all the land that feeds/drains into the
river and its tributaries.
Mississippi River is the largest drainage basin in the US.
The western divide is the Continental Divide in the Rocky
Mountains
and the eastern divide is the Appalachian Mountains.
(All the rain and water in between the Rocky Mountains and
the Appalachian Mountains drain into the Mississippi River.)
Drainage Basins in Virginia that drain into the
Chesapeake Bay Watershed are:– Potomac River - in our area (separates Northern VA with MD)
– Rappahannock River – south of us near Fredericksburg, VA
– York River – from Charlottesville to Williamsburg, VA (Yorktown)
– James River – across the middle of VA (Jamestown)
Divide is the high/elevated land that separates
one drainage basin from another.
• The major divide in the
US is the Continental
Divide, which lies in the
Rocky Mountains.
– Rain and water that drain
down to the west side of
the Rocky Mountains
eventually feed into the
Pacific Ocean, and rain
and water that drains down
to the east side of the
Rocky Mountains will
eventually feed into the
Atlantic Ocean.
How fast a river moves (how much sediment
it erodes and transports) depends on:
• velocity of water
• gradient of river
• discharge and shape of the river channel.
Velocity – distance water travels in a
given amount of time.
It depends on the gradient and the discharge.
Gradient – steepness of the slope of
the river.
• Usually a large gradient at steep slopes (near the
source of the river)
• Usually a small gradient , gentle flowing as it
approaches base level or sea level.
Discharge – amount (volume) of water that
passes a certain point in a given amount
of time.
• Changes based on where the river is flowing (climate),
and in tributaries are flowing into the main river
Dendritic Meandering
Load - eroded rock and soil material carried
downstream by the river.
• 3 ways a river carries it load (material): solution,
suspension, and bedload
Solution – minerals (from bedrock)
dissolved into the solution (water)
(Calcium, magnesium, bicarbonates) – most of the
minerals come from the groundwater seeping into the
stream.
Suspension – rock materials floating in
water (not sinking)
• mostly clays, silts, and fine sands that make the water look muddy.
• The faster the stream flows the more turbulence (the more the river gets stirred up) and the muddier the water becomes.
Bedload - usually sands, pebbles/gravels,
and boulders that are too heavy to be
carried in suspension, but instead get
moved along the stream bed (bottom of the
stream).
Stream Deposition - streams will
deposit/drop some of its load when its velocity
or discharge slows.
Example – like after a flood, when the flood waters subside/go down)
Stream DepositionDeposition occurs here (on the
inside of a curve in the river
Stream Deposition Occurs When:
Velocity Decreases
• Channel widens
• Curving bank or rock outcrop
• Empties into a sea or lake
Discharge Decreases
• Water is diverted for irrigation or for city water supply
• River passes through an arid region (water is evaporated and seeps into ground)
Depositional Features:
• Delta – fan-shaped deposit that is formed when a
river flows into a large body of water (sea, lake,
ocean, etc).
Depositional Features: Delta
Depositional Features:
Alluvial Fan – fan-shaped deposit on land
when a river flows down a steep hill/mountain
and it meets dry land at the base of the
mountain.
How do Rivers Form?
Features of Rivers
Features of Rivers
Features of Rivers
Canyons have
steep (almost
vertical) sides.
Colorado River
cut the mile-
deep Grand
Canyon
Groundwater
Groundwater
Groundwater
Groundwater
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