GEOG 2OC3 Lecture Notes - Lecture 2: Axial Precession, Glacial Landform, Axial Tilt
27 Jun 2018
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WEEK 2
Paleogeography
Epiric Sea: An inland sea cause by high sea levels.
One covered most of the interior of N.A (North America) during the Mesozoic era.
High sea levels are what often led to the characteristic limestone caps of the lowlands e.g. Niagara
escarpment of southern Ontario.
The Ice Age
The Pleistocene period marks the most recent glacial episode in the Northern hemisphere, with ice
sheets covering roughly 30-40 degrees in latitude (around N.Y)
Global plate distribution was stabilized.
There are 3 orbital controls on glaciation: Orbital eccentricity, axial precession, axial tilt.
Axial precession: The slow and continuous change in the orientation of earth’s rotational axis.
Caused by gravitational pull on earth by moon and sun.
Axial tilt: The angle of tilt bw the earths rotational axis and orbital axis. The earth’s axial tilt is
the reason we have seasons.
Glacial cycles: Isolation drops, sea ice gathers at pols, glaciers advance/scour landscape, sea level
lowers/atmosphere becomes drier, insolation rises, glaciers retreat, sea level rises/atmosphere become
warmer and wetter.
Glacial landforms are formed by either erosion by ice/meltwater or deposition by ice/meltwater.
Moraines: Ridges or mounds of glacial material deposited close to the ice margin, often associated with
uneven topography.
Eskers: Winding ridges of stratified sand and gravel frequently km long, possibly formed from meltwater
running through glacial tunnels.
The retreat of the glaciers formed the great lakes.
find more resources at oneclass.com
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Document Summary
Epiric sea: an inland sea cause by high sea levels. One covered most of the interior of n. a (north america) during the mesozoic era. High sea levels are what often led to the characteristic limestone caps of the lowlands e. g. niagara escarpment of southern ontario. The pleistocene period marks the most recent glacial episode in the northern hemisphere, with ice sheets covering roughly 30-40 degrees in latitude (around n. y) There are 3 orbital controls on glaciation: orbital eccentricity, axial precession, axial tilt. Axial precession: the slow and continuous change in the orientation of earth"s rotational axis. Caused by gravitational pull on earth by moon and sun. Axial tilt: the angle of tilt bw the earths rotational axis and orbital axis. The earth"s axial tilt is the reason we have seasons. Glacial cycles: isolation drops, sea ice gathers at pols, glaciers advance/scour landscape, sea level lowers/atmosphere becomes drier, insolation rises, glaciers retreat, sea level rises/atmosphere become warmer and wetter.
