"First there was the ice; two miles high, hundreds of
miles wide and many centuries deep. It came down from the darkness of the world,
and it hung over the eaves, and our Michigan country lay along the line of the
overhang. To be sure, all of the ice was gone. It had melted, they said, ten
thousand years ago; but they also pointed out that ten thousand years amounted
to no more than a flick of the second hand on the geologic time clock."
--
Bruce Catton. Waiting for the Morning Train.
Glaciers Scoured Ancient Rock Formations
The underlying bedrock of the lower
peninsula of Michigan is a series of sedimentary rock layers deposited
like stacked saucers by ancient seas that covered much of Michigan for millions
of years. Several times huge sheets of ice advanced from the north and receded.
In the
process, they scoured the bedrock; created huge channels for lakes; deposited
ridges of sand, gravel, clay, and other material carried along by the glaciers;
pushed, crushed, and packed material deposited earlier; and melted to fill icy lakes
and streams that eroded the landscape further.
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Glaciers Today: |
As a result, bedrock in the Arcadia area is mostly hidden by
relatively loose material and rocks deposited by moving glaciers. The
landscape has pronounced hills and valleys bounded by bluffs on the west next to
the eastern shore of Lake Michigan, the remnant of the western part of ancient Lake Algonquin.
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Michigan Today from Space
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Dunes Formed from Blowing Sand
Rivers and streams carried sand to the beach of Lake Michigan, and as lake levels increased, bluffs eroded adding more sand to the beach. Waves cleaned and sorted the sand to remove silt and clay and to separate fine sand and gravel. As beaches widened and dried, prevailing winds carried the sand up and east to form large coastal dunes. Eventually plants gained a foothold, which stabilized some dunes and encouraged additional plant growth. Because of the combination of course soils, diverse terrain, the moderation of severe temperatures (due to the large, nearby body of water), and the dynamic nature of dunes, small areas of landscape could support a greater number of plants than most comparably sized areas in the state.
The Developing Landscape
As glaciers finally receded and the icy lakes warmed, Michigan's landscape evolved from frozen tundra to the mosaic of northern hardwoods and pine forests that eventually drew lumbermen to the area. Early on, re-advancing glaciers wiped out invading vegetation, but the invasion was relentless, so as the glaciers receded, glacial till and blown-in loess were covered by vegetation re-invaded the area.
Around 11,800 years ago,
Arcadia's landscape consisted of tundra next to glaciers not far to the north.
Several miles inland you would have found open, northern style parkland with
mammoths and herds of caribou. Eventually these gave way to mastodons, smaller
more scattered herds of caribou, giant beaver, elk, and moose.
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The Arcadia Area |
About 9,900 years ago, Arcadia would have been situated in a spruce pine forest. Subarctic grassland with scattered woodlots was eventually replaced by forest with a closed canopy in some places. About this time the ancestors of all native Americans were probably in the area. These people were modern humans that probably crossed the land bridge from Asia. They followed large game, especially caribou, but they also hunted small game and foraged for edible plants.
Early native Americans lived along the shores of lakes and rivers in small groups and moved often. As a result, little obvious was left behind in general to mark their presence and identify places worth closer examination by archeologists. As lake levels rose, what was left behind was destroyed or hidden.
Around 5,000 years ago, the Arcadia area landscape was evolving into a northern hardwood forest with pine oak forest land to the immediate south and east. Extensive sand dunes formed along Lake Michigan's eastern shores. White pine was prominent on stabilized dunes. Jack pine may have been found in specialized habitats.
The stage was set. The next time the landscape would change significantly would be when European lumbermen and farmers cleared the forest and began extensive tillage.