Term
| What trends in stable oxygen isotopes would you expect to see during a glaciation? |
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Definition
1) Enriched Oxygen-18 in the oceans due to fractionation during evaporation and storage of O-16 in glaciers
2) Increased uptake of oxygen 18 by organisms with calcium carbonate skeletons (due to lower kinetic energy of larger isotopes which makes them easier to incorporate at low temperatures) |
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Term
When was the most recent glacial Maxima?
Bonus: what was this last Maxima called? |
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Definition
about 20,000 years ago (or from 35 kya to 12.9 kya)
It was called the Wisconsin Stage |
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Term
| When did the modern ice age (aka the late Neogene Ice Age) begin? |
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Definition
| Midway through the Pliocene, about 3.2 Million years ago |
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Term
| List types of evidence that geologists can use to reconstruct patterns of the Modern Ice Age (i.e. the timing and extent of glaciers within the last 3.2 Million years)? |
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Definition
Lines of Evidence include all of the following:
*Erratic boulder deposits
*Glacial till ex. Moraines
*The depression of the land and subsequent isostatic rebound ex. Hudson's Bay
*Glacial scouring ex. as seen in the Canadian shield
*Changes in sea level (transgressive and regressive facies)
*Species migratory patterns
*Foraminifera oxygen isotopes
*Terrestrial plant pollens |
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Term
True or false:
Glacial minima and maxima both occur during an ice age. |
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Definition
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Term
True or false:
Glaciers have expanded and contracted many times within the modern ice age. |
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Definition
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Term
| True or false: The last glacial minima (before the current minima) was about 125, 000 years ago. |
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Definition
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Term
| What factors initiated the modern ice age? Compare these to the factors that initiate glacial minima and maxima. |
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Definition
Ocean currents (altered by the formation of the Isthmus of Panama) initiated the current ice age. CO2 levels may have played a role as well (although current, low levels precede modern ice age by about a 2 million years)
Glacial cycles (maxima and minima) are driven by Milankovitch cycles and especially rapid changes can be caused by Heinrich Events. |
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Term
| What is a Heinrich Event? What is its effect? |
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Definition
| Heinrich event is a massive discharge of icebergs that release sedimentary debris to the sea as they melt. These have an unexplained rapid warming effect that can lead to a glacial minima. |
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Term
| What chain of events led to the Mediterranean salt deposits? Roughly when did this occur? |
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Definition
Closing of Tethys sea way (as Africa and India collided with Eurasia)
Closing off of Mediterranean waters from the Atlantic Ocean to the West, and subsequent hyper-salinification caused by evaporation
This occurred between 6 and 5 MYA |
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Term
| When did the Neogene extinction event associated with spread of C4 grasses occur? |
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Definition
In the late Miocene, about 6 to 7 Million years ago
N.B. this was prior to Modern Ice Age |
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Term
Place the following events of the Neogene in the correct chronological order:
C4 grasses become more prominent
Younder Dryas Boundary
Extinction of many herbivores
Modern Ice Age begins
Most recent glacial maxima
Hypsithermal Interval
Isthmus of Panama closes |
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Definition
Oldest
*C4 grasses become more prominent
*Extinction of many herbivores
*Isthmus of Panama closes
*Modern Ice Age begins
*Most recent glacial maxima
*Younder Dryas Boundary
*Hypsithermal Interval
Most recent |
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