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Mrs. Flagler's Science Page 2006-2007 |
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Old Notes |
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EQ: How do paleontologists
use radioactive decay to determine the absolute age of rocks? atom- the smallest part of
matter that still has the characteristics of that matter element- a pure substance
that contains all of the same kind of atom radioactive decay- an unstable
element decays, or breaks down, gives off energy and becomes another element; geologists compare the amount of unstable element
before it decays, to the amount of the new element it has changed into. This gives them the absolute age of the rock. half-life- the rate at which
radioactive decay of an unstable element takes place EQ: The time between Precambrian
Time and the present is divided into 3 units.
How do scientists characterize these units? geologic time scale- a record
of life forms and geologic events in Earth’s history; needed because of the very large span of time in Earth’s
history; shows that organisms became more complex as time went by. Precambrian Time- the time
between the Earth’s formation from dust and gases (4.6 billion years ago), to the first mass extinction (544 million
years ago). • Lasted 4 billion years • The simplest of organisms appeared well into this period
of time • Ended in a mass extinction of life forms 3 Eras- divisions of time
from Precambrian Time to the present 1. Paleozoic Era- lasted for 300 million years; invertebrates formed
during this time; ended with another mass extinction 2. Mesozoic Era- lasted 180 million years; “meso” means
middle; Age of Reptiles; ended with mass extinction caused by a meteorite or asteroid that hit Earth and caused so much dust
that the Sun was covered and plants, then animals died, scientists believe. 3. Cenozoic Era- lasted 65 million years so far; “ceno”
means recent; Age of Mammals; humans appeared in the Quaternary Period EQ: How do fossil records support
the theory of evolution? (notes continued) evolution- the gradual
change in living things over long period of time. Fossil records tell paleontologists that living things evolved over time
or became extinct. (Ex: elephants that we looked at during class) clues to tell the relative
age of rock: 1) law of superposition- oldest
layers on the bottom, youngest layers on top (unless disturbed) 2) index fossils- if we know the
age of the fossil, we can tell that the rock in which it is found is at least that old. 3) extrusive or intrusive igneous
rock- both are younger than the rock that surrounds them 4) faults-rock found in fault lines
is younger than rock that surrounds it 5) unconformity- a gap in the geologic
history of rock due to erosion
Paleontology EQ: How are fossils formed? paleontologist- a scientist
who studies fossils fossil- the preserved
remains or traces of living things; these are formed when living things die and are buried by sediment; sediment then slowly
hardens into rock and preserves the shape of the organism types of fossils: 1) petrified fossils-
fossils in which mineral replace all or part of an organism. means “turned into stone” (ex: petrified wood) 2) mold- most common
form of fossil, along with casts; hollow area in sediment in the shape of the organism 3) cast- copoy of the
shape of an organism; dissolved minerals and sediment can seep into empty space of a mold and forms a cast 4) carbon film- an extrememly
thin coating of carbon on rock; when organism dies it can give off carbon gas
which escapes leaving a film of carbon behind; all living things contain carbon 5) trace fossils- provide
evidence of activities of ancient ofganisms, such as a footprint of an animal; gives clues to the behavior and habits of the
organism 6) preserved fossil remains-
organism is trapped in tar, amber or ice fossil record- provides
evidence about the history of life on Earth by examining fossils; this is why the study of fossils is so important extinct- an organism
that no longer exists dating of rock: relative age- the age
of the rock compared to the ages of other rocks (younger or older) absolute age- the number
of years since the rock formed (determined by radioactive dating) Law of Superposition-
in horizontal layers of sedimentary rock, the oldest layer is at the bottom.
EQ: What cycle constantly wears
down and rebuilds Earth’s surface? erosion- movement of
weathered rock and soil by natural forces (water, wind, waves, glacial action) sediment-material such as rock particles
and soil that is moved by erosion deposition- laying
down of sediment after weathering and erosion; a constructive force weathering- a destructive
force that breaks down rock into small particles
deposition
mass movement- a force
that moves sediment downhill due to gravity. Examples: 1) landslide
(mudflow)- very rapid movement of rocks, soil, debris; mudflow has much more water involved 2) slump- a chunk of rock and soil that looks like
it has been scooped from the side of a slope 3) creep- a very slow movement of rock and soil that
leaves the landscape looking deformed how a river forms: raindrop>
runoff (water that flows during rainfall that carries soil particles with it; does NOT soak into the soil)> rill
(rainwater fills tiny cracks in soil during rainfall)> gully ( a groove or channel in which rainwater flows after
a rainshower; is usually dry when no rain)> stream (a larger channel in which rainwater flows; may dry up in severe
drought conditions)> river (even larger channel in which water flows; does not dry up in drought conditions) EQ: How does the deposition of sediment
shape Earth’s landforms? drainage basin- the
land area from which a river and its tributaries collect their water flood plain- the flat
wide area of leand along a river meander- a loop-like
end in the course of a river that is formed by deposition of sediment in one part of the loop oxbow lake- a meander
that has been cut off from the river by deposition of sediment delta- a landform formed
by sediment deposited at the mouth of a river where it flows into an ocean or lake alluvial fan- a wide,
sloping deposit of sediment formed where a stream leaves a mountain range
EQ: How does sediment play a role in the formation of Earth’s landforms?
EQ: What is soil and how is it formed? Soil soil- a mixture of
organic and inorganic substances, water and air, that supports living things formation of soil- soil is formed
by the weathering of rocks and other substances weathering- a process
that breaks down rock and other substances at Earth’s surface 2 types of weathering: 1) mechanical weathering- rock is physically
broken down into smaller pieces ·
abrasion- grinding away of rock by rock particles carried by water, ice,
wind and gravity ·
freezing and thawing- water expands as it freezes inside of rock causing
it to break. Ice wedging- ice acts like a wedge to force rock apart ·
release of pressure-erosion removes rock, causing it to exert less pressure
below, causing flaking and cracking of the rock on the surface ·
animal actions- animals burrowing underground cause the wearing away of
rock ·
plant growth- plants growing in cracks in rock send down roots that force
rock to break apart 2) chemical weathering-
the process that breaks down rock due to chemical processes- always involves water as an agent ·
water- water weathers rocks by dissolving it ·
oxygen-certain substances oxidize by forming compounds with oxygen and water; rust
is an example- it causes rock containing iron to soften and crumble ·
carbon dioxide-forms carbonic acid when carbon dioxide dissolves in water vapor;
this mild acid causes weathering ·
living organisms- lichens and other produce weak acids in their roots that combine
with rainwater to chemically weather rock ·
acid rain- burning fossil fuels produces pollutants which mix with rain
and fall as acid rain; this acid can weather rock EQ: How does water play a role in
the chemical weathering of rock? See above notes on chemical weathering EQ: Why is soil one of Earth’s
most valuable resources and how can we protect it? 1) inorganic materials- comes
from the rock that has been weathered bedrock- layer of rock that lies beneath the soil (becomes sand, silt or clay
when weathered) 2) organic materials-
plant and animal material in soil; humus-decayed remains of plants and animals; has been decomposed by bacteria, protists
and fungi; creates spaces for air and water to enter soil; rich in nitrogen, sulfur, potassium and phosphorus ·
soil horizons- layers of soil that differ in color, texture and composition 1) horizon C- composed
of bedrock and weathered rock 2) horizon B- known
as subsoil- composed of clay and other substances that have washed down from Horizon A, but contains little humus 3) horizon A-
topsoil- a crumbly, dark brown soil that is made of humus, clay and minerals. Organisms such as earthworms live here and
break up the soil and create spaces to hold air and water, as well as acting as decomposers; litter- loose layer of
leaves and dried plant material that is scattered on top of the topsoil 1) equal parts
of sand, silt and clay (45%) 2) air- (25%) 3) water- (25%) 4) organic matter-
(5%) 1) soil can be exhausted,
or lose its fertility 2) soil may be polluted by
chemicals or by mining 3) desertification-
making of desert conditions from areas that were fertile before; caused by drought so that soil blows away 4) overgrazing or land use-
causes destruction of sod ( thick mass of tough roots at the surface of the soil) so that the soil that was kept in place
and held in moisture, was exposed and dried out. (Dust Bowl- area in the southern Plains states were derought and topsoil
loss caused soil to turn to dust and formed dark clouds so that people had to leave their homes. ·
soil conservation- management of soil to prevent its destruction 1) contour plowing-
plowing fields along the curves of a slope; prevents runoff 2) conservation plowing-
dead weeds and stalks are left in the ground to return soil nutrients, retain moisture and prevent erosion 3) crop rotation-different
crops are planted in a field each year to add different nutrients to the soil, or allow the field to lie fallow (or
unplanted) so that nutrients aren’t depleted. 4) land reclamation-
process of restoring land to a more natural, productive state after it has been depleted of nutrients; it is expensive; better
to protect it in the first place than have to restore it after it is damaged
EQ: What is municipal solid waste
and how is it managed? municipal solid waste-
waste materials produced in homes, businesses and schools. NOT in construction, agriculture and industry. 3 ways that we manage MSW: 1) bury it- we use sanitary landfills
now; people used to bury it or throw it out sanitary landfill- an area that has been
dug out and filled with a liner to prevent leakage of pollutants such as leachate (liquid, decayed waste) and methane
gas (produced when decomposition and digestion occur). Methane gas is explosive and is piped out of the landfill and can
be used for fuel. Leachate can also be piped out of the landfill so it doesn’t smell bad. 2) burn it- incineration- the
burning of waste in an enclosed facility. can create pollution must still dispose of waste 3) recycle- reusing, reducing
or reshaping materials to reduce waste. plastics contain a resin that can be melted down
to form clothing, carpet material
EQ: How are minerals formed? crystallization- the
process by which atoms are arranged to form crystal structure. 2 ways that minerals are formed: 1) through crystallization of melted
materials -as magma or lava cools, the minerals are formed with it -if the magma or lava cools rapidly, the crystals are small -if the magma or lava cools slowly, the crystals are large 2) through the crystallization of
materials dissolved in water -solution- a mixture in which one substance is dissolved in another substance alloy- a solution in which one metal is
dissolved in another. -as the water cools, the minerals and elements that are dissolved in it form crystals -
when water evaporates, the dissolved mineral is left behind ore- a rock that contains
a metal or other mineral smelting- the process
by which a useful metal is separated from the ore by melting. vein- a narrow channel
of a mineral that is very different from the surrounding rock. Notes on Minerals
EQ EQ: What changes occur on Earth’s surface due to the movement of plates? plate tectonics- the geological theory that states that pieces of Earth’s lithosphere are in constant, slow motion,
driven by convection currents in the mantle. scientific theory- a well-tested concept that explains a wide range of observations. Very different from a scientific
law. plate boundary- a place where plates meet a) transform boundary- a place where 2 plates slip past each other, going in opposite directions. Earthquakes frequently
form here. Ex: San Andreas Fault in California b) divergent boundary- where 2 plates pull away from each other, such as in the mid-ocean ridge. Also occur on land. A
rift valley forms along divergent boundaries. Ex: Rio Grande River basin c) convergent boundary- where 2 plates push together, or collide. Mountain ranges form here. Less dense plate (continental
or oceanic) is pushed above the more dense plate. Ex: Appalachian Mts., Himalayan Mts. : What are the components of Earth’s interior and how do they
differ? Layers of the Earth: -seismic waves- waves given off by earthquakes;
scientists use their speed and paths through parts of earth’s interior to know more about regions that we can’t
see -indirect evidence- evidence gathered
that we can’t actually see -crust: its depth is 5-40 km under Earth’s
surface; its composition is made of oxygen, silicon, aluminum, calcium, sodium, potassium and magnetism
a) continental crust- made up mostly of granite
b) oceanic crust- made up mostly of basalt -mantle: its depth is approximately 2,990 km;
its upper layer is called the asthenosphere, which is solid rock that is fluid-like; its composition is made of silicon,
oxygen, iron and nickel -core: its composition is made of iron and nickel a) outer core- depth is 2,250
km; its temperature is 2,200 degrees Celcius and it is molten material that is not solid b) inner core- depth is 1,200
km, its temperature is 5,000 degrees Celcius and it is solid -these layers increase in temperature and pressure
with depth into the Earth -floating on top of the asthenosphere and composing the lower part of the crust and the top part of the mantle is the lithosphere. This
part of Earth is rigid and is broken into regions called plates. EQ: How are convection currents
in Earth’s mantle set in motion? Heat transfer- heat energy is always transferred
from warmer objects to cooler objects, not the other way around. 3 ways heat energy is transferred: a) conduction- where
a warmer object touches the cooler object (Ex: the pot actually is warmed by touching the burner of the stove) b) radiation- sun’s
infrared energy warms Earth this way; heat energy is transferred through empty space (Ex: your hands are warmed if you put
them near the hot pot) c) convection- heat energy
is transferred through the movement of fluids (Ex: the soup is heated in the pot); involves the rising and falling in a circular
motion, of the fluid due to density, heating and cooling and gravity EQ: What was Alfred Wegener’s
theory about continents and what evidence did he provide to support his theory? Pangaea- from “all lands”;
a supercontinent formed from all the present continents that existed about 100 million years ago Continental drift- the movement of continents
across Earth’s surface, due to convection currents in the asthenosphere 3 sources of evidence to support
Wegener’s theory of continental drift: 1) from landforms such as mountain
ranges, coal beds 2) from fossils- fossil-
a trace of an ancient organism that has been preserved in rock 3) from climate- glacial deposits
indicate that the areas where they are found were once close together. mid-ocean ridge- the longest mountain
range on Earth; under the ocean except for places like Iceland; sonar used to detect its presence. rift valley- a valley in the middle of the mid-ocean ridge trench- a dip in the ocean floor, usually
found where the ocean nears a continent sea-floor spreading- the sea floor spreads
apart along both sides of the mid-ocean ridge as new crust is added Earthquakes
Notes EQ:
How do stress forces affect rock? earthquake-vibrations that result from movement of rock beneath Earth’s surface deformation- the change in shape or volume of Earth’s crust stress- a force that acts on rock to change its shape or volume over millions of years 3 types of stress: a) shearing- pushes rock in
opposite directions b) tension- pulls on crust,
stretching rock c) compression- squeezes rock
until it folds or breaks When
stress builds up in a rock, it fractures along a fault (a break in Earth’s crust where slabs of crust slip past
each other); this occurs along plate boundaries because the motion of the plates there shear, pull or compress rock so much
that the crust breaks. 3 types of faults: a) strike-slip fault- rocks
on either side of the fault slip past each other sideways; caused by shearing b) normal fault- one block of
rock lies above the fault and one lies below the fault; hanging wall- the block of rock that lies above the fault and
slides down due to tension; footwall- the block of rock that lies below the fault. c) reverse fault- one block of rock
is pushed upward (hanging wall) past the footwall by the stress of compression Earthquakes
are cause by stress and friciton. Friction determines how rocks move along a
fault. If there is low friction, they slide and don’t stick. If there is
high friction, blocks of rock stick together (or lock together). When stress is greater than friction, the blocks unlock quickly,
setting off an earthquake. a) P waves- primary waves; the first to reach the epicenter;
compress and expand b) S waves- secondary waves; the second to reach the epicenter;
move up and down or side to side c) surface waves- last to reach the epicenter but carry the
most energy; cause most severe ground movement seismograph- instrument used to measure and record vibrations of seismic waves Geologists
use seismic waves to locate an earhtquake’s epicenter. Seismic waves travel at different speeds. The difference between
the arrival times of P and S waves determines the distance that the earthquake’s epicenter is from the seimograph station.
The farther away it is, the greater the time between the arrival of the P waves and the S waves. magnitude-
strength of earthquake as determined by seismic waves and howmuch movement of plates along fault 3
scales used to measure earthquakes: a) Mercalli scale- rates earthquakes
by damage to people, buildings b) Richter scale- rates earthquakes
by size of seismic waves as measured by a seismograph c) Moment Magnitude scale- rates
by the total amount of energy they produce; advantage- can be used to rate earthquakes of all sizes and whereever they are
located. Dangers
associated with earthquakes: Safety: Buildings
should be on shock absorbing materials Drop,
cover, hold Stand
in doorway EQ: What factors determine
the force of a volcano’s eruptions? volcano-
a weak spot in Earth’s crust where molten material from the mantle comes to the surface magma-
molten material, water and gases from deep within the Earth lava-
magma that reaches Earth’s surface Parts of a volcano: a) magma chamber- where magma collects
inside a volcanl b) pipe- long tube which connects magma
chamber to Earth’s surface c) vent- opening in volcanowhere magma
comes out d) lava flow- area covered by lava as
it comes out of vent e) crater- bowl shaped area where lava
collects around a vent What determines a volcano’s
force- a) the amount of gas dissolved in the magma b) how thick or thin the magma is c) the temperature of the magma d) its silica content ·
hot magma is thin and has less silica content ·
cooler magma is thick and has more silica content ·
quiet volcano (from thinner magma) o pahoehoe-hot, thin lava from quiet eruptions o aa-slower, cooler lava from quiet eruptions o explosive
volcanoes- if lava is thick and blocks pipe and gases under pressure blow out, it will be loud. The lava will cause a pyroclastic
flow (it cools quickly and hurls ash, cinders and bombs) Types of volcanoes- a) active- is eruptiing or is showing
signs of erupting b) dormant- not active now but may be
in the future c) extinct- unlikely to erupt again
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Meteorology: Chapter 15
EQ: Which medium heats and cools faster, land or water?
EQ: What are the 4 types of fronts and what kind of weather do they bring?
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