Quiz 1 Flashcards
What was the legend of the Parallel Roads of Glen Roy?
that it was the hunting paths of ancient Celtic warriors
What did Darwin believe about the Parallel Roads of Glen Roy?
that Scotland was submurged by the sea and had eventually risen, creating wave cut marine beaches
Did Darwin defend his theory of the origin of the Parallel Roads?
No, he scrambled to defend it and eventually gave up
What is the history/cause of the Parellel Roads of Glen Roy?
Glacial ice: vast ice sheets covered much of the Northern Hemisphere and were capable of carving parallel terraces into valley walls and easily move erratic boulders
Who recorded signs of smoothed and striated bedrock that ice had overridden and evidence of tills, moraines and erratic boulders?
Jean de Charpentier (1830s)
With regards to glaciers, who realized that many of the same features were present at lower altitudes in norther Europe on a vastly larger scale (e.g. immense gravel deposits)
Louis Agassiz’s Ice Age (1836)
conlcusion: features had glacier origin, although they had long vanished
Do scientists agree with Louis Agassiz’s Ice Age theory?
Yes
Ice Age in America
Who spotted traces of continental ice sheets in western New York
Timothy Abbott Conrad (1839)
Ice Age in America
Geologists figured out that fossil plant layers sandwhiched between sheets of glacial till & different weatherin of moraines. What were these clues of?
Multiple episodes of ice advance and retreat
Ice Age in America
Who mapped the four distinct glacial stages?
Thomas Chamberlin
Ice Age in America
What were Thomas Chamberlin’s four distinict glacial stages?
- Nebraskan (followed by the Aftonian interglacial)
- Kansan (Yarmouth interglacial)
- Illoian (Sangamon interglacial) and
- Wisconsin (Holocene interglacial)
Causes of the Ice Ages
Who created a mathematical model of the worlds climates to predect variation in climate across space and through time?
Milutin Milankovitch
Cause of the Ice Ages
What did the Milankovitch Cycles calculate?
orbitally driven insolation changes by season and by latitude over long periods of earth history
Causes of the Ice Ages
What is insolation?
exposure to the sun’s rays
Causes of the Ice Ages
What does insolation vary by?
by latitude and season and due to the earth’s orbit being jostled by the gravitational tug of the sun & other plants in a complex Newtonian cotillion
Causes of the Ice Ages
____ tilt reduces insolation and cools down winters and summers
higher
Causes of the Ice Ages
When changes in the eccentricity and the tilt occur what does this trigger?
It triggers the precession of the equinox
Understanding Glaciation
Who saw that changing insolation might be the key to understanding glaciation?
Wladimir Koppen
Understanding Glaciation
______ are primarily a Northern Hemisphere phenomenon
Massive, continental- scale ice sheets
with the exception of Antartica and small glaciers high in the Andes and
Understanding Glaciation
What happens to glaciers when the temperatures get warmer?
Ablation overcomes the accumaltion of ice and the glacier stops moving and may even retreat
Understanding glaciation
What happens to glaciers when they pause?
Upon pausing, the glacier deposits a gravelly end moraine, evidencing a time when climate was relatively stable
Understanding glaciation
What can make the glaciers move quickly?
Rapid climate change
The present landscape (glaicers)
There were at least ____ major glacial-interglacial epsiodes (of varying intensity) over the last milion years & perhaps twenty over the entire Ice Age
ten
The present landscape (glaicers)
Only 4 glacial epsiodes were found due perhaps to the buldozing action of later glacial advances. The present landscape was shaped primarily by the Wisconsin glacial stage. How is the Wisconsin glacial stage subdivided?
- Early Wisconsin (a coolder period marking the onset of this last major glacial episode)
- Middle Wisconsin (a relatively warmer period, with glaciers present on the land but much reduced)
- Late Wisconsin ( a period of expanded glacisers with ice volume reaching its max and sea levels falling to their min)
- Holocene (the present interglacial which we are in today)
