Wisconsin Glaciers
The biggest thing that ever happened to Wisconsin was the glacier, last seen heading north out of the state one hundred centuries ago. This prodigious giant stood a mile or more tall and covered millions of square miles. And as it disappeared, it gave the Wisconsin landscape its final shape, creating our sparkling lakes and rearranging our rivers.
Picture an immense snowdrift, thousands of feet deep, a mind-boggling accumulation of countless centuries, so massive it covered half the continent. Imagine the enormous weight compressing the snow into ice, squeezing downward, forcing gigantic tongues outward in every direction, ponderously scraping and gouging, bulldozing off hills, digesting rocks, filling valleys, detouring rivers, leveling forests.
Then it all changes. Centuries of milder weather gnawed away at the glacier. It melted gradually, moving by fits and starts, falling back and then grinding forward again, icy water pouring like sweat off its rounded brow. Inside the glacier was a great churning cement mixer, engulfing and pulverizing rocks of every size, which, as the ice melted, were unloaded in great quantities as rich soils in one place, and find sand or rocks in another. The glacier advanced, pulled by gravity, flowing outward from its area of great thickness near Hudson Bay, scraping and screeching across bedrock, but it melted back quietly, a vast ice field turning to slush, wasting away. This last glacier left behind Wisconsin’s varied landscape like no other.
This happened 20 times during the ice age that came to Wisconsin.
-- Howard Mead in "Ancient Wisconsin."
The biggest thing that ever happened to Wisconsin was the glacier, last seen heading north out of the state one hundred centuries ago. This prodigious giant stood a mile or more tall and covered millions of square miles. And as it disappeared, it gave the Wisconsin landscape its final shape, creating our sparkling lakes and rearranging our rivers.
Picture an immense snowdrift, thousands of feet deep, a mind-boggling accumulation of countless centuries, so massive it covered half the continent. Imagine the enormous weight compressing the snow into ice, squeezing downward, forcing gigantic tongues outward in every direction, ponderously scraping and gouging, bulldozing off hills, digesting rocks, filling valleys, detouring rivers, leveling forests.
Then it all changes. Centuries of milder weather gnawed away at the glacier. It melted gradually, moving by fits and starts, falling back and then grinding forward again, icy water pouring like sweat off its rounded brow. Inside the glacier was a great churning cement mixer, engulfing and pulverizing rocks of every size, which, as the ice melted, were unloaded in great quantities as rich soils in one place, and find sand or rocks in another. The glacier advanced, pulled by gravity, flowing outward from its area of great thickness near Hudson Bay, scraping and screeching across bedrock, but it melted back quietly, a vast ice field turning to slush, wasting away. This last glacier left behind Wisconsin’s varied landscape like no other.
This happened 20 times during the ice age that came to Wisconsin.
-- Howard Mead in "Ancient Wisconsin."