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Science 8th Grade Final


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deductive reasoning- specific to general
inductive reasoning- general to specific
Dependent Variable- changes because of the independent
Independent variable- factor that changes in the experiment
Constants- variables that don't change
Treatments- groups of trials with the same independent variable
Draw Conclusions
using trends to tell what the data means
meters (cm/km/mm)
grams (kg/mg)
liters (ml. mL)
differences between the metric and english
metric uses the base of ten
Formula of density
D= m/V
Density- Importance to earth science
warmer water on top, colder water on the bottom
Measuring density
take the mass of the object, and then use displacement in the water
all living things
evolution not defined by the geography but by the dominant organism
Composition and water vapor
78% Nitrogen
21% Oxygen
1% Other
Atmospheric layers
-Troposphere- 0-12 km; where the weather is
-Stratosphere-12-50 km; ozone layer
-Mesosphere- 50-80 km; shooting stars blow up
-Thermosphere- 80-550+; satelites orbit
-Ionosphere- 80-550
-Exosphere- 550+
Hydrosphere Composition/ during the ice age
97% Marine, 2% Ice, 1% Fresh
ice age- 96% Marine, 3% Ice, 1% Fresh
Hydrosphere formation of the oceans
Timing- 400 million years ago
-Volcanos- small amounts of water in the rocks, melt .031% of the mantle, would have enough to fill the oceans
-Comets- made of rock and ice, would blow up and release water vapor
Hydrosphere- percentage on the earth, volume and maximum depth
74% of water on the earth
Volume: 1360 x 10^6 km^3
Maximum depth:11,035m (Marianas trench
Compositon- sediment,crust, upper mantle
Alferd Wegner's idea and evidence
continents were drifting apart
-Geometric fit of the continents
-Glaciers in equatorial regions
-Fossils- land animals found in water, etc.
-Rock Matching- rock layers agreed
Scientific Objections to Wegner's theory
sediment buildup patterns do not agree and no mechinism to move the continents
discovery of the MOR
echosounding technology
Hess' theory of seafloor spreading
seafloor spreading
a mechanism that did move the seafloor
Magnetic striping pattern
earth switched poles every one in a while and when the MOR "erupted" some molten rock, it would harden where ever the poles were
Divergent Boundaries
moved apart and created new land
passive volcanism, little to no seismic activity
MOR, Iceland, East African rift valley and the Red Sea
Conservative Boundaries
plates rubbing against eachother and sticking
seismic activity, no volcanism
creates mountain chains and earthquakes
Convergent boudaries- Continental oceanic
oceanic plate subducts under the continental one
lots of volcanism, some seismic activity
Sumtra, South America
Oceanic oceanic
the older plate subducts under the yonger one
seismic activty and volcanism
continental continental
-Two plates collide, putting pressure on each other
until the two suture together creating mountains
-Characterized by seismic activity, no subduction or volcanism
Cause of tectonic plate movement
convection currents/cells
Modern evidence for movement
apparent polar wonder
Cause of earthquakes
tectonic plates moving together
types of waves
-P-waves- parallel to the energy
-S-waves- moves perpendicular to the energy
-Surface waves- moves in any direction, causes the most damage
location where the earthquakes energy is released
directly above the focus
amount of energy released
richter scale
expression of strength or magnitude, logrithmic-10
how do you find where the earthquake started
line graph, find where p and s waves are apart, look on the graph and use triangulation
Predicting Earthquakes
-Time since the last earthquake- longer since, more chance of an earth quake
-Frequency- frequent, greater chance
-Magnitude of the last quake- more tension, less chance
-Foreshocks- cant determine how big they are
Major Fault zones
Charleston Fault,
New Madrid fault
San Andres fault
Cause of volcanism
Cinder Cone
steep narrow, infrequent, violent, indistict layers, Percutin
gentle slope, wide, uniform, frequent,
Maura Loa and Kiluwa
moderate slope, distinct layers, erupts at different times
Vesivus, Mt. Shasta
Location of volcanic activity on Earth
1. Divergent Boundaries
2. Convergent boundaries
a. O/O
b. O/C
3. Hot spots- in ocean except for Yellow Stone
Damage caused by volcanoes
1. Lava flows-Burn buildings, covers roads, 5 mph
2. Pyroclastic flows-700 degrees celcius, Travel 200 km/hr,Superheated gas, rock, glass, dust, ash
3. Falling ash-Covers roads, homes in ventilation systems
4. Rising sulfurous gasses- rains solface to acid rain causes deforestation, corrosion, etc.
5. Climate Change-Locally or globally, 1% sunlight decreases
Bishop Ussher
used bible to calculate earthl 6,000 year old earth
theory that the earth was formed quick and sudden
Charles Hutton
observed sedimentation rates and layered rock
says the earth is older than 6,000 years
formed the earth like it does today, calls for an older earth, supports the Darwinian evolution
William Thompson
Assumed earth had been cooling steadily since its birth,Calculates a 200 million year earth
John Joly
Assumed earth collected salts from erosion at constant rate, 90 million years
used radioactive decay estimated 4.54 billion years
half lives (parent to daughter) first three
1:1 = one half life
1:3 = two half lives
1:7 = three half lives

3:1 = a half live
7:1 = one fourth
15:1= one eighth
Law of Superposition
Ones on the bottom are the oldest,ones on top are the youngest
Index Fossils
Must be widespread, short-lived and easily fossilized and have bones
Geologic time subdivided
Eons, Eras and Periods
Beginning of geologic time/beginning of the Hadean Eon
4.6 billion years ago
Hadean eon- 4.6-3.9 billion years bp
Evolution of the first life/beginning of the Archean Eon
3.9-2.5 billion years bp
Simple bacteria, lots of continental formation
Oxygen accretion in the atmosphere/mid-late Proterozoic Eon
2.5-570 billlion years bp
Stramolites made oxygen in the atmosphere and killed most life
Cambrian Explosion/begin. of Phanerozoic Eon/Paleozoic Era
Cambrian explosion
Mutation of different organisms, world wide
570-248 million years bp
Pangea, amphibians and Gymnosperms
Silurian period- life colonizes land
End-Permian Exinction/beginning of the Mesozoic Era
90% died, largest extinction
-Ice age- climate changes, able to kill 90% on land and 95% in water
-Volcano- rise in volcanism, can't kill everything
-Colliding Continents- continents dry out, problems for amphibians, decresing coast lines, condensed smaller place and decreasing where animals live
-Mesozoic- 245-65 MYA BP
-Rifting, warm and cool climate, dinosaurs
K-T Extinction/beginning of the Cenozoic Era
70% died
-Iridium, common in space
Chicxhlub- impact from the crater, near Mexico, cold weather
-Cenozoic Era- 60 million years, diverse mammals, last ice age
i. What were continents like early in geologic time? Late?
Earlier, the continents were very spread apart; it looked like there wasn’t much land. Then more land was there and it then started to collide, then it broke off, moved and is there where it is today
Have the continents always been moving?
Yes, they have always moved, and are still moving today
How have continents assembled in the past? What does this suggest about future continental movement?
They just move until they collide and then it breaks apart. It shows that in the future the continents will collide and parts might break off with another continent, and the formation of the continents will be different
Is global warming/cooling a natural occurrence?
Yes, but we are helping it go faster
How have these temperature changes affected life on Earth?
When there are ice ages, many animals can't handle it, like reptiles.
Increasing complexity
In Achaean there was simple life, then in Cambrian, complex life and then mammals and reptiles started to form and Mesozoic and Cretaceous period dinosaurs and bigger mammals started to appear
Mass extinctions followed by rapid evolutionary radiations
Happens because after extinction life has to evolve and grow to fill those gaps
Effects of geologic processes on living things
Continental drift- no effects, volcanism- can kill but not everything, meteor strikes- can kill everything (End Permian)
extinction events-
Proterozoic(single-celled organisms only)
oxygen and stramatolites
Extinction event- Vendian
soft bodied multi cellular organism
largest exstiction
two continents collided, decreasing habitats
Extinction event-K-T
Dinosaurs, killed 70%
Meteor hit
infinite mass, density, heat and no dimenstion
Estimated time since the big bang
13.7 billion years ago
Georges Lemiatre
First proposed the big bang theory, used math and proposed it to Albert Einstein, but he didn't agree
Henrietta Leavitt
discovered the Cepheid variable- star whose brightness varies in a pattern, didn't get credit for her work, was able to measure the stars that weren’t in our galaxy
Edwin Hubble
used Henrietta’s work, discovered red-shift galaxies, didn't go any farther than his equations, didn't evaluate more on it
George Gamow
developed and supported the big bang theory
Penzias and Wilson
Had a sound in their telescope and they called gamow and found Cosmic Microwave background radiation
Got a nobel prize
Galactic redshift
tells how far away planets are, red is farther away from blue
Baryonic dark matter (MACHOs and super black holes)
MAssive Compact Halo Objects
Non-baryonic dark matter (WIMPs)
Weakly Interacting Massive Particles
1 AU=...
150 million km
Composition of the early Universe
75% hydrogen
24% helium
.7% lithium
.3 Other
Big Bang theory vs. Steady State model
Finite vs. Infinite
Dated vs. Eternal
CMB radiation
Found by Arno Penezias and Robert Wilson in 1964
Bell Laboratories
Trying to study the stars with a radio telescope, had a lot of background noise,
Won the Nobel Prize
Released energy after the big bang (singularity)
Left over big bang
iii. Abundance of light elements
universe began, wasn’t made of atoms, had quirks,
when universe cooled and their were atoms, 300,000 years after big bang
alpher, mathematically found what to expect from the universe (75% H, 24% He, .7% Li, .3% other)

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