It is dark under the hundreds of feet of heavy ice.

We were here before it came, creeping so slow.

Our vista was wide, and its beauty was more than nice.

Then came the endless wind, the cold and snow.

But all things must change, so we waited, as time won’t matter.

Eventually we see the cold, but beautiful, blue,

Though it was not the sky above our yearning water.

It was the eerie blue of glacial hue.

Soon the cracks and breakings start,

Opening the ice to let the real sky in.

As the ancient ice broke apart,

Dripping, running, soon to be flowing again.

The ice is gone, except kettle chunks won’t go.

Future lakes, for all to see, buried deep and staying cold.

But now on top of the Prairie Coteau

Waiting for us to drain and mold.

Valleys and hills, our job ahead,

Going south for hundred of miles.

Wearing and breaking the rock of red,

Like a giant’s hand forming sand piles.

Great tusks standing by our shores.

Megabeasts of many shapes

None knowing what lies in store,

For not too far, extinction waits.

Shooting ahead with a force of power,

Grabbing red rock and throwing it around.

Flattening the land like a great rock mower,

Gouging holes in the rock and ground.

Hitting an ice block of giant size,

Sending us north with speed and power.

Moving rock from where it lies,

Digging the bed lower and lower.

Now the bed does drop as our flow is small.

Diving down the red rock cliff in foam.

We are now part of the great waterfall,

Curving back southward to roam.

At last we are complete, or journey done.

From a deep, icy start high on a hill,

Serenaded by giant friends, we have come.

To the great Missouri and on to the sea we’ll run.

But, deep in our bottoms, our shores, our waves, we surely know,

The global heating will bring it back, sooner than not.

That great blue ice giant who starts as snow,

Will freeze us solid, and end our lot.

Mick Zerr, 2012

Epilog: The geological history of the Big Sioux River, and its falls, starting in the high Coteau just north of Summit SD, has one of being frozen solid numerous time by great ice sheets, the last time ending around 11,500 BP in the final leg of the Wisconsin ice age.

As ice melted each time, the river cut and forged through glacial soil and rock and eventually into the ancient Sioux Quartzite. The river is draining the great Prairie Coteau as the ice sheet melts, sending immense amounts of water churning south and cutting a deep, wide valley. The length of the river fluctuates around 400 miles, due to channel changes, etc. Chunks of ice, covered by till and wind blown loess did not melt with the major sheet. These formed many of the glacial lakes in the area, with Wall Lake as a good example.

When it hit a large ice dam/moraine by Sioux Falls, it is re-routed back north in a speedy curve around the ice that breaks up the protruding quartzite creating the Falls of the Big Sioux and the big bend of the Big Sioux River. Heading back south, it meets the great Missouri just north of Sioux City. In every case of intense global warming, during the last few million years, the warming is followed quickly by an advancing ice sheet, due to climate changes related to the shutting down of the warm ocean currents by the influx of fresh water from fast melting land  ice. The present interglacial warmth is one of the greatest warmings among the ice age predecessors.