What two major geological changes resulted across the North American continent during, and because of, the planet’s last period of heavy glaciations (the last ice age) when massive sheets of ice expanded across Canada and the northern half of the United states, as well as other areas of the northern hemisphere. Solution Glacial stages in North America Northern hemisphere glaciation during the last ice ages. The set up of 3 to 4 km thick ice sheets caused a sea level lowering of about 120 m. The major glacial stages of the current ice age in North America are the Illinoian, Sangamonian and Wisconsin stages. The use of the Nebraskan, Afton, Kansan, and Yarmouthian (Yarmouth) stages to subdivide the ice age in North America have been discontinued by Quaternary geologists and geomorphologists. These stages have all been merged into the Pre-Illinoian Stage in the 1980s.[18][19][20] During the most recent North American glaciation, during the latter part of the Wisconsin Stage (26,000 to 13,300 years ago), ice sheets extended to about 45 degrees north latitude. These sheets were 3 to 4 km thick.[19] This Wisconsin glaciation left widespread impacts on the North American landscape. The Great Lakes and the Finger Lakes were carved by ice deepening old valleys. Most of the lakes in Minnesota and Wisconsin were gouged out by glaciers and later filled with glacial meltwaters. The old Teays River drainage system was radically altered and largely reshaped into the Ohio River drainage system. Other rivers were dammed and diverted to new channels, such as the Niagara, which formed a dramatic waterfall and gorge, when the waterflow encountered a limestoneescarpment. Another similar waterfall, at the present Clark Reservation State Park near Syracuse, New York, is now dry. The area from Long Island to Nantucket was formed from glacial till, and the plethora oflakes on the Canadian Shield in northern Canada can be almost entirely attributed to the action of the ice. As the ice retreated and the rock dust dried, winds carried the material hundreds of miles, forming beds of loess many dozens of feet thick in the Missouri Valley. Isostatic rebound continues to reshape the Great Lakes and other areas formerly under the weight of the ice sheets. The Driftless Zone, a portion of western and southwestern Wisconsin along with parts of adjacent Minnesota, Iowa, and Illinois, was not covered by glaciers. .

1. What two major geological changes resulted across the North American continent during, and
because of, the planet’s last period of heavy glaciations (the last ice age) when massive
sheets of ice expanded across Canada and the northern half of the United states, as well as other
areas of the northern hemisphere.
Solution
Glacial stages in North America
Northern hemisphere glaciation during the last ice ages. The set up of 3 to 4 km thick ice sheets
caused a sea level lowering of about 120 m.
The major glacial stages of the current ice age in North America are the Illinoian, Sangamonian
and Wisconsin stages. The use of the Nebraskan, Afton, Kansan, and Yarmouthian (Yarmouth)
stages to subdivide the ice age in North America have been discontinued by Quaternary
geologists and geomorphologists. These stages have all been merged into the Pre-Illinoian Stage
in the 1980s.[18][19][20]
During the most recent North American glaciation, during the latter part of the Wisconsin Stage
(26,000 to 13,300 years ago), ice sheets extended to about 45 degrees north latitude. These sheets
were 3 to 4 km thick.[19]
This Wisconsin glaciation left widespread impacts on the North American landscape. The Great
Lakes and the Finger Lakes were carved by ice deepening old valleys. Most of the lakes in
Minnesota and Wisconsin were gouged out by glaciers and later filled with glacial meltwaters.
The old Teays River drainage system was radically altered and largely reshaped into the Ohio
River drainage system. Other rivers were dammed and diverted to new channels, such as the
Niagara, which formed a dramatic waterfall and gorge, when the waterflow encountered a
limestoneescarpment. Another similar waterfall, at the present Clark Reservation State Park near
Syracuse, New York, is now dry.
The area from Long Island to Nantucket was formed from glacial till, and the plethora oflakes on
the Canadian Shield in northern Canada can be almost entirely attributed to the action of the ice.
As the ice retreated and the rock dust dried, winds carried the material hundreds of miles,
forming beds of loess many dozens of feet thick in the Missouri Valley. Isostatic rebound
continues to reshape the Great Lakes and other areas formerly under the weight of the ice sheets.

2. The Driftless Zone, a portion of western and southwestern Wisconsin along with parts of
adjacent Minnesota, Iowa, and Illinois, was not covered by glaciers.