Download Earth History Study Guide Answers are in RED 1) How has scientific

Earth History Study Guide
Answers are in RED
1) How has scientific understanding of Earth’s past changed with time? We used to
think that the world was dominated by larger catastrophic events (catastrophism),
but now we think that Earth’s history has been dominated by the same small
changes and cause and effect we see today. Scientists also used to think that
the continents had not moved. Today we know from the evidence that supports
plate tectonics that the continents have moved in the past and continue to move
today.
2) What are the methods we use to figure out dates in Earth history? Be specific.
We use relative and absolute dating. One method of relative dating we use is the
Law of Superposition which tells us that in undisturbed sedimentary rock, the
oldest are at the bottom and the youngest are at the top. One method of absolute
dating that we use is radiometric dating.
3) Put the following events in order based on the geologic timeline from what came
first to last: Humans, Mammals, Dinosaurs, Fish, Reptiles, Flowers
Fish, Reptiles, Dinosaurs and Mammals, Flowers, Humans
4) What major event in Earth history allowed dinosaurs to become successful? The
super ridiculous extinction that wiped out 95% of life at the Permian-Triassic
boundary on the geologic timescale.
5) What major event in Earth history allowed mammals to become successful? The
ridiculous extinction that wiped out the dinosaurs 65 million years ago at the K-T
boundary.
6) What evidence did Wegener have to support his theory of Continental Drift?
Continents lined up like puzzle pieces, fossils from different continents matched
up where those pieces fit together, and landforms matched up on the different
continents.
7) What evidence came about in the 1950s (after Continental Drift) that supported
Plate Tectonics? The ocean floor was rugged and young, evidence of repeated
reversals of the Earth’s magnetic field in the past, seafloor spreading, and a
concentration of earthquakes along plate boundaries,
8) Draw an example of fossils that would be evidence for each of the following
environments:
a. Forest—plant fossil
b. Ocean—fish or seashell fossil
c. Desert—scorpion fossil
9) How do each of the following plate boundaries move:
a. Convergent—colliding
b. Divergent—dividing
c. Transform--sliding
d. Subduction—more dense crust dives under the less dense crust
10) What features do each of the following plates produce and what is a real world
example:
a. Convergent—mountain building, ex: Himalayas
b. Divergent—seafloor spreading or rift valleys, ex: Mid-Atlantic Ridge
c. Transform—earthquakes and faults; ex: San Andreas Fault
d. Subduction—volcanoes; ex: Cerro Negro in Nicaragua
11) How do canyons and valleys between mountains form? Weathering and erosion
by water (rivers) cause canyons. Weathering and erosion by water or ice
(glaciers) cause valleys
12) How do mountains form? Two continental convergent plates colliding
13) What’s the difference between a constructive and destructive force? Constructive
forces create landforms by building things up on the surface of the Earth.
Destructive forces create landforms by breaking things down on the surface of
the Earth.
14) Which of these are constructive and which are destructive: deposition,
weathering, erosion, mountain building, landslides, volcanoes
Constructive: deposition, mountain building, landslides, volcanoes
Destructive: weathering, erosion, volcanoes and landslides
15) What drives plate tectonics? Convection currents in the mantle and ridge
push/slab pull at the crust
16) What’s the difference between oceanic and continental crust? Oceanic crust is
denser, usually younger, primarily made up of basalt, and thinner. Continental
crust is less dense, usually older, primarily made up of granite, and thicker.
17) How does climate change act as a reinforcing feedback loop? As more ice forms
it causes increased reflectivity of the Earth’s surface which causes sunlight to
bounce away, which causes the Earth to get cooler, which causes more snow
and ice to form, which furthers the feedback loop. As more ice melts, you have
more vegetation which absorbs more heat and sunlight, which causes the Earth
to warm more, which causes more ice to melt and more vegetation to grow,
which further drives the reinforcing loop.
18) What causes climate to change? Changes in the strength of the Sun,
composition of the atmosphere, changes in ocean currents and plate tectonics,
reflectivity of Earth’s surface
19) How do we know how climate has changed in the past? Ice cores, geologic
record, sediment cores, and the changing location of species
20) What is the primary theory for what caused the dinosaur extinction? An asteroid
colliding with Earth, the resulting tsunami, and ash and gas in the atmosphere
halting photosynthesis
21) What evidence supports the primary theory for what caused the dinosaur
extinction? Finding tsunami deposits in the Brazos River Basin, Texas,
determining that rocks taken from the Chicxulub crater are the same age as the
K-T boundary, discovering gravitational field anomalies on the Yucatan
peninsula, from surveys done for oil exploration, finding high levels of iridium in
the K-T boundary layer, identifying spherules and shocked quartz in Haiti, finding
that an isotope of plutonium is not in the K-T boundary layer, and observing
differences in foraminifera fossils above and below the K-T boundary layer
22) How do earthquakes relate to plate tectonics? By looking at the major places that
earthquakes occur on Earth, we can identify where the major plate boundaries
are
23) How does radiometric dating work (what is being measured and what does it tell
you)? You are measuring how much of a particular element (like carbon) has
decayed or decreased. The less of the element you have, the more time has
passed.
24) What is “global warming” and what’s causing it? Global warming is the increase of
the Earth’s average surface temperature due to a build-up of greenhouse gases in
the atmosphere.
25) Explain three effects of global warming in your own words. Rising sea levels
because of ice and glaciers melting, increased extreme weather like tropical storms
and hurricanes, and rising temperatures because there is less ice to reflect the
sunlight and more grass to absorb the heat.