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