The Glacial History of Michigan Science Foundations 1

The Glacial History of Michigan Science Foundations 1

The Glacial History of Michigan n The landforms of Michigan are a result of major changes brought about by continental glaciation. n Landforms can be depositional or erosional in nature.

The Glacial History of Michigan n Glacial landforms dominate the surface of the whole state except the western half of the U. P. , where eroded remnants of some of the oldest mountains on earth are found. There is considerable diversity in MI—from glacial lake plains near Detroit, to sand dunes bordering Lake Michigan, to massive moraines in the northern lower peninsula. The slope and soil variations associated with the landforms are major factors in the agriculture, economy and population density in various parts of Michigan.

The Glacial History of Michigan n The last ice age occurred during the Pleistocene Epoch (a division of time). n It began 2 million years ago and ended approximately 12, 000 years ago. n We live in the Recent Epoch today (12, 000 years ago to the present).

The Glacial History of Michigan n n The last ice age was the fourth major ice age in Earth’s 4. 6 billion year history. In addition to the northern U. S. and Canada, the last ice age created the glacial landforms of northern Europe and Siberia. n Others occurred: – – – 2. 0 billion years ago 600 million years ago 250 million years ago (on Pangaea!)

The Glacial History of Michigan n During an ice age, it is not cold all the time. Long periods of cold temperatures and glaciation are broken up by equally long periods of warm temperatures during which glaciers recede and sea level rises. n The warm periods are called interglacials, meaning “in between times of glaciers. ”

The Glacial History of Michigan n Look at the graph in your packet and observe the changes in temperature during the Pleistocene Epoch. n Focus on the names of the glacial and interglacial Periods.

ANSWER THE FOLLOWING: *How many glacial periods were there? *About how often did they occur? *According to the graph, what is global temperature doing now? *Is the last Ice Age over yet? Explain.

The Glacial History of Michigan n n There were 4 periods of glaciation: Nebraskan, Kansan, Illinoisan, & the Wisconsinan (which created the landforms seen in the Great Lakes region). See the diagram in the packet.

The Glacial History of Michigan n n During a glacial period, snow fall accumulated into layers of ice in 4 regions of North America. Label and color the map in your packet according to the directions on the diagram.

Greenland Alpine Keewatin Labrador ICE SPREADING CENTERS

The Glacial History of Michigan n n These huge masses of ice were up to 10, 000 feet or more in thickness. They moved south into the U. S. leveling existing hills, filled in valleys, blocked drainage patterns of rivers, and gouged out major basins.

The Glacial History of Michigan n The Great Lakes were carved out from river valleys over the entire Pleistocene Epoch. n See the diagram in your packet. n With each advance of the ice, they got wider & deeper.

The Glacial History of Michigan n n The depth of the lake is determined by the thickness of the ice at the time of glaciation. The farther north the lobe of ice, the thicker it was. Consequently, the lakes get more shallow in the southern Great Lakes region. LAKE: n n n GREATEST DEPTH: Superior = Michigan = Huron = Ontario = Erie = 1, 333 ft. 925 ft. 725 ft. 283 ft. 212 ft.

The Glacial History of Michigan n The Great Lakes are 5 of the lakes in a 5, 000 mile long string of lakes through central and western Canada. n Each was carved by huge continental ice sheets over the last 2 million years.

The Glacial History of Michigan n n The moving ice carried sediments (small pieces of rock) long distances. Rocks from Canada have been found in Ohio and Indiana. As the ice melted, the sediments were deposited, creating huge landforms. Some sediments were deposited in large ridges and hills while others were carried away by vast amounts of meltwater streaming from the melting ice sheets. See the diagrams in the packet for more details.

The Glacial History of Michigan Another major result of glaciation was the creation of a large number of inland lakes and wetlands. n More than 11, 000 inland lakes are largely the result of water accumulating in depressions left by passing glaciers. n Much of the swamp land of Michigan was drained for agriculture. This accounted for the loss of 50% of Michigan’s wetlands. n

The Glacial History of Michigan n The flattest areas of southeast Michigan are plains that are the result of deposits on the bottom of ancient lakes. n Detroit and the northwest suburbs used to be under an ancient lake!

The Glacial History of Michigan The last diagram shows the movement of the ice over Michigan during the last glacial period. n This advance created the landforms and features seen today. n