ESS 301 MIDTERM EXAM QUESTIONS AND ANSWERS
WITH COMPLETE SOLUTIONS VERIFIED LATEST UPDATE
How do we define the ancient coastline of North America, and what does this
indicate ?
respect to the ratio of two isotopes of strontium present
in magma which has risen through the crust. This indicates whether the underlying crust
is old and continental
or young and oceanic. We're primarily interested in the recent arrivals, but there's also
the Belt Group.
What is the The Belt Rocks (NW Montana), and what does it include
70,000 ft (about 13 miles) of monotonous sedimentary rocks, slightly
metamorphosed. They include fine sandstones, red mudstones, and "dirty" limestones
and range in age from
1.7 Ga to 800 Ma, resting on Archaean basement rock (2.3 to 2.8 Ga). All have been
metamorphosed.
Where was the Belt sediment deposited, and what kind of water landscape and
climate is included in this region.
- deposited in a broad, shallow expanse of water, perhaps an arm of the sea,
surrounded
on at least two sides by dry land (maybe a failed rift).
, - This was relatively still water surrounded by a gentle
landscape of thick, lifeless soils.
- The climate was generally hot and humid
What are more characteristics of the Belt Group
-They contain no volcanic deposits (no evidence of nearby active plate boundaries)
-no sand dunes (warm
everywhere on the planet, so a relatively stagnant atmosphere), even though they span
a range of 800 Ma.
They
- also show no evidence of bioturbation, so sedimentary structures are well preserved.
What are some of the Atmospheric effects of the belt group?
The atmosphere had enough oxygen to cause oxidation of some sediments and was
rich in carbon dioxide,
producing a greenhouse environment, with nothing but algae to take advantage of it
(which they did).
what is occurring when, abundant algae growth is producing more oxygen
the atmosphere and simultaneously sequestered a lot of
the carbon dioxide, setting the stage for more complex life but also plunging the planet
into a colder climate.
This would have been self-reinforcing in the absence of anything to eat the living and/or
dead algae, giving us
the icehouse effect and a snowball Earth.
WITH COMPLETE SOLUTIONS VERIFIED LATEST UPDATE
How do we define the ancient coastline of North America, and what does this
indicate ?
respect to the ratio of two isotopes of strontium present
in magma which has risen through the crust. This indicates whether the underlying crust
is old and continental
or young and oceanic. We're primarily interested in the recent arrivals, but there's also
the Belt Group.
What is the The Belt Rocks (NW Montana), and what does it include
70,000 ft (about 13 miles) of monotonous sedimentary rocks, slightly
metamorphosed. They include fine sandstones, red mudstones, and "dirty" limestones
and range in age from
1.7 Ga to 800 Ma, resting on Archaean basement rock (2.3 to 2.8 Ga). All have been
metamorphosed.
Where was the Belt sediment deposited, and what kind of water landscape and
climate is included in this region.
- deposited in a broad, shallow expanse of water, perhaps an arm of the sea,
surrounded
on at least two sides by dry land (maybe a failed rift).
, - This was relatively still water surrounded by a gentle
landscape of thick, lifeless soils.
- The climate was generally hot and humid
What are more characteristics of the Belt Group
-They contain no volcanic deposits (no evidence of nearby active plate boundaries)
-no sand dunes (warm
everywhere on the planet, so a relatively stagnant atmosphere), even though they span
a range of 800 Ma.
They
- also show no evidence of bioturbation, so sedimentary structures are well preserved.
What are some of the Atmospheric effects of the belt group?
The atmosphere had enough oxygen to cause oxidation of some sediments and was
rich in carbon dioxide,
producing a greenhouse environment, with nothing but algae to take advantage of it
(which they did).
what is occurring when, abundant algae growth is producing more oxygen
the atmosphere and simultaneously sequestered a lot of
the carbon dioxide, setting the stage for more complex life but also plunging the planet
into a colder climate.
This would have been self-reinforcing in the absence of anything to eat the living and/or
dead algae, giving us
the icehouse effect and a snowball Earth.
