Self-study
P1
Discovered in 1993, the site known as Ukhaa Tolgod, in the Gobi desert of Mongolia, is one of the world's best sources of fossils from the Late Cretaceous period, which ended about 65 million years ago. ███ █████████ ███████ ███ ██████ ███████ ████ ████ █████ █████████ ████████ ██████████ ████ ████ █ ███████████ ███████ ███ ███████████████ ████ ██████████ ███
Phenomenon ·
Well preserved fossils
How did they form?
Hypothesis ·
Sandstorm buried the animals
Hypothesis wrong ·
New evidence calls sandstorm hypothesis into question
P2
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Details of Phenomenon ·
Three different types of sandstone at the site
1st Type ·
Well-defined structure
Consistent with sandstorm hypothesis...
2nd Type ·
Tilt and layering
Also consistent with sandstorm hypothesis...
3rd Type ·
No layering; contains large pebbles
Inconsistent with sandstorm hypothesis because the pebbles are too large to have been windblown. This is the type that contains all of the vertebrate skeletal fossils.
P3
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Alternate Hypothesis ·
Sand avalanche caused fossils
Avalanche trapped animals in its path, resulting in the pristine quality of the remains.
P4
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Phenomenon ·
Avalanche / sandslides
What caused them?
Hypothesis ·
Unclear; clay played a role
Unclear but likely clay and rain played a role.
Evidence ·
Modern sand dunes
Implications of hypothesis ·
Sandslide hypothesis suggests area was not sterile desert
Passage Style
Critique or debate
Phenomenon-hypothesis (RC)
27.
Which one of the following, ██ █████ ████████ ███ █████████ ███████ ███ ████████ ████ ███ ███████ █████ ██████████ █████████ ████ █████ ██ █████ ██████ ████ ██████ ██ ███████████
a
Scientists have never ████████ ████████ ███████ █████ ██████ ██ █ █████████ ██ ███ ████ ███████
Whether scientists have directly observed animals being killed by a sandslide in the Gobi doesn’t bear on whether a sandslide could have killed animals in the Gobi desert 65 million years ago. As long as sandslides can kill animals, the authors’ theory can be supported by other evidence. No one needs to directly witness a death due to sandslide in order for such a death to be a reasonably possible occurrence.
b
The area of ███ ████ ██████ ██ █████ █████ ██████ ██ ███████ ██ █████████ ███ █ ██████ ████ ██████
The current state of the site doesn’t impact whether the site could have been a stable dune 65 million years ago.
c
In areas of ███ ████ ██████ █████ ████ █████ ███████ ████████ ██████████ ████████ ███████ ████ ████ █████ ██ ███ ██████ ████ ██ █████████ █████████ ██ ███ ██████ ██████████
We already know that no fossils were found in the second type of standstone at Ukhaa Tolgod. So whether fossils have been found in that kind of stone at different sites has no impact. The argument is about Ukhaa Tolgod.
d
Geologists believe that ██ ██████████ ████ ████████ ██ ███ ████ ██████ ███ ██ █████ █ ███████ ██████
The argument is about what happened 65 million years ago. The fact sandslides haven’t occurred in 5 million years doesn’t relate to whether they could have occurred 65 million years ago.
e
There are several ███████ █████████ ████ ███ ███████ ███ █████ ████ ██ █████████ █████████ ██ ███ ██████ ██████████
This weakens by providing an alternate explanation for how the fossils can be found in the third type of sandstone. Remember, the author jumped to sandslides as the explanation merely because