Sequence of Glacial Events
Minnesota has been covered, at least in part, by a glacier numerous times during the Quaternary ice age. In order of increasing age, these advances took place during the Wisconsinan and Illinoian stages; prior to this continental ice sheets advanced into and retreated from Minnesota multiple times during the Pre-Illinoian Stage.
The ice moved into Minnesota at different times from three glacial centers, the Labradorian center in northern Quebec and Labrador; the Patrician center, just southwest of Hudson Bay; and the Keewatin center, northwest of Hudson Bay.
Deposits left by the continental ice sheets advancing from these three centers reflect the characteristics of the rocks over which they passed. The Keewatin ice encountered the Cretaceous limestones and shales of Manitoba and the Red River Valley, whereas the Patrician and Labradorian ice moved over iron-rich Pre-Cambrian crystalline rocks of the Canadian Shield.
Read more about this topic: Glacial History Of Minnesota
Famous quotes containing the words sequence of, sequence and/or events:
“It isn’t that you subordinate your ideas to the force of the facts in autobiography but that you construct a sequence of stories to bind up the facts with a persuasive hypothesis that unravels your history’s meaning.”
—Philip Roth (b. 1933)
“We have defined a story as a narrative of events arranged in their time-sequence. A plot is also a narrative of events, the emphasis falling on causality. “The king died and then the queen died” is a story. “The king died, and then the queen died of grief” is a plot. The time sequence is preserved, but the sense of causality overshadows it.”
—E.M. (Edward Morgan)
“By the power elite, we refer to those political, economic, and military circles which as an intricate set of overlapping cliques share decisions having at least national consequences. In so far as national events are decided, the power elite are those who decide them.”
—C. Wright Mills (1916–1962)