Transcript Review slides

Review slides
Topographic Maps
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Streams and maps
Prime Meridian
The prime
meridian is 0
degrees
longitude.
From Pole to Pole, the Prime
Meridian covers a distance of
20,000 km. In the Northern
Hemisphere it passes through
UK, France and Spain in
Europe and Algeria, Mali,
Burkina Faso, Togo and
Ghana in Africa. The land
mass crossed by the Meridian
in the Southern Hemisphere is
Antarctica.
http://www.portcities.org.uk/london/upload/img_400/Greenwich_meridian_20040512123830.gif
Stream erosion and deposition
What do you see happening here?
Evolution of a Meandering Stream
http://www.wwnorton.com/college/geo/egeo/
flash/14_1.swf
Where is sediment deposited and why?
Sedimentation
http://www.classzone.com/books/earth_science/terc/content/visualizati
ons/es0604/es0604page01.cfm?chapter_no=visualization
Transport of sediment in stream
http://www.classzone.com/books/earth_science/terc/content/visualiz
ations/es1303/es1303page01.cfm?chapter_no=visualization
How can you tell the difference between a
young river and an old river?
• You can judge the age of a river by the
erosion it has made in the geography of
the land, such as the Colorado river has
cut canyons into the earth. New rivers are
more turbulant because they haven’t had
the time to smoothen the rocks and terrain
it flows over.
Age of a River
• Youthful river
– a river with a steep gradient that has very few
tributaries and flows quickly. Its channels erode
deeper rather than wider.
• Mature river
– a river with a gradient that is less steep than those of
youthful rivers and flows more slowly. A mature river
is fed by many tributaries and has more discharge
than a youthful river. Its channels erode wider rather
than deeper.
• Old river
– a river with a low gradient and low erosive energy.
Old rivers are characterized by flood plains.
Young River with steep banks
Older River with broad flood plain
Course of a River
Drainage Basin Features
Erosion vs weathering
• Erosion is the removal of sediment, soil or
rocks in the natural environment. Due to
transport by wind, water, or ice; by downslope creep of soil and other material
under the force of gravity or by living
organisms, such as burrowing animals
• Weathering is the process of chemical or
physical breakdown of the minerals in the
rocks
Streams and Hydrology
Now Check your understanding...
Try out this Hydrological Cycle / Drainage Basins
Walk the Plank Game
and check your understanding of Drainage Basin
Features by matching up these key terms and
definitions within the 30 second time limit!
Stars
• What are stars made of?
– Mostly Hydrogen (H) and Helium (He), with
bits of heavier stuff like oxygen, carbon, iron,
etc.
– This is a similar composition to that of the
universe as a whole.
Star Life Cycles
• Video
• http://www.metacafe.com/watch/752173/lif
e_cycle_of_star/
• Site
• http://www.seasky.org/celestialobjects/stars.html
Star Life Cycle
Focus on Main Sequence of
Hertzsprung-Russell cycle
• Main Sequence is where stars spend the
majority of their lives.
• What trends do you notice about the
Main Sequence stars?
Effect of Size on Stars
• More massive stars exert stronger
gravitational pulls on the materials that
comprise them.
• This results in greater pressure at the core
and thus higher temperatures.
• This leads to a bluish tint.
• Fusion reactions occur faster at higher
temperatures, so these stars burn out
more rapidly, in as little as thousands of
years.
Small Stars
• Less massive stars are dim and red.
– They have low core temperatures and
undergo fusion very slowly.
– So slowly, in fact, that even though they are
starting out with much less mass than the
most massive stars, they can stay in the Main
Sequence for billions of years.
– Our sun, which is pretty medium, is expected
to last for about 10 billion years (only 5 billion
more to go!)
Interactive HR
• answer the questions here:
http://aspire.cosmicray.org/labs/star_life/support/HR_static_real.
html
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RED GIANT
VARIABLE
Planet formation
• The Sun formed from a nebula (interstellar
cloud of dust, hydrogen gas, helium gas
and plasma
• The inner planets are mostly rock and
metal
• The outer planets are mostly ice and gas
Solar System
• The solar system was born about 4.5 billion years ago,
when something disturbed and compressed a vast
cloud of cold gas and dust -- the raw material of stars
and planets. The disturbance may have been a collision
with another cloud, or a shock wave from an exploding
star.
• Whatever the cause, the cloud fragmented into smaller,
denser pockets of matter, which collapsed inward under
the pull of gravity. In perhaps 100,000 years, one of the
pockets, called a nebula, condensed into a volume about
the size of the present-day solar system. In the dense
center of the nebula, a star formed -- our Sun.
• The newborn Sun was still surrounded by its nebula,
which was spread into a thin disk because the nebula
was spinning slowly.
Solar System
• Atoms and molecules within the nebula
combined to form larger particles. The Sun
determined what kinds of particles could exist.
Close to the Sun, solar heat vaporized ices and
prevented lightweight elements, like hydrogen
and helium, from condensing.
• Inner Planets
This zone was dominated by rock and metal,
which clumped together into ever-larger bodies,
called planetesimals, eventually forming the
rocky inner planets: MVEM
• Outer Planets
In the solar system's outer region, though,
it was chilly enough for ices to remain
intact. They, too, merged into
planetesimals, which in turn came together
to form the cores of the giant planets:
JSUN-- P
Solar System
• Plenty of hydrogen and helium remained in this region
far from the Sun. As the giant planets grew, their gravity
swept up much of these leftovers, so they grew larger
still. Jupiter and Saturn contain the largest percentages
of hydrogen and helium, while Uranus and Neptune
contain larger fractions of water, ammonia, methane,
and carbon monoxide.
• Most of the moons probably formed at the same time
as their parent planets. Earth's Moon probably formed a
bit later, when a body several times as massive as Mars
slammed into our planet. The collision blasted a geyser
of hot gas and molten rock into orbit around Earth; the
material quickly cooled and coalesced to form the Moon.
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Steps to the formation of stars and planets:
Clouds of gas form within galaxies.
Formation of structure within the gas clouds, due to "turbulence" and activity of new
stars.
Random turbulent processes lead to regions dense enough to collapse under their
own weight, in spite of a hostile environment.
As blob collapses, a disk forms, with growing "protostar" at the center.
At the same time, bipolar outflows from forming star/disk system begin.
Material is processed, moving in from the blob to the disk. What is not lost in the
outflow builds up on the protostar.
When the protostar begins to undergo fusion, it becomes a real star.
Once the outflow ceases and the "accretion" phase that lead to the buildup of the star
ends, a disk of "leftover" material is left around the star.
At or near the end of the star-formation process, the remaining material in the
"circumstellar disk" (a.k.a. "protoplanetary disk") forms a variety of planets.
Eventually, all that is left behind is a new star, perhaps some planets, and a disk of
left-over ground-up solids, visible as a "Debris Disk" around stars other than the Sun,
and known as the "Zodaical Dust Disk" around the Sun.