I can’t see the lake again today. As I look outside all I see is gray mist. Temperatures have risen way above freezing, a huge contrast to yesterday morning when it was near zero. Today the foot and a half of snow that has been on the ground is putting lots of moisture in the air and fog shrouds everything.
I know the lake is there. I know it is only hidden, not gone, and that tomorrow, or even later today, I will see it again. I trust that will happen. Yet water can disappear permanently. So today, if I cannot see the water to write about it, I can spend a few minutes reflecting on how large bodies of water might disappear.
When I do interpretative tours the Dinosaur Discovery Museum here in Kenosha, which I have been doing for grade school children for about a year now, we show the kids pictures of the Hell Creek Formation in Montana. That’s a geological area where students and professors from Carthage College dig every summer, and where Little Clint (a young T. Rex) was found. Hell Creek is a popular site for digs, as it is a fossil rich area.
According to http://www.wikipedia.com/ it is a series of fresh and brackish-water clays, mudstones, and sandstones deposited during the Maastrichtian, the last part of the Cretaceous period, by fluvial activity in fluctuating river channels and deltas and very occasional peaty swamp deposits along the low-lying eastern continental margin fronting the late Cretaceous Western Interior Seaway.
Those are lots of technical terms to tell me that the Western Interior Seaway was a huge inland sea that split the North American continent and covered almost half the continent. At its deepest, it may have been 600 to maybe 900 meters deep. Although that may not be deep for a sea, that’s a helluva lot of water. Now, about 100 million years later, it’s gone, and some of the portions of the Hell Creek Formation and the rest of Montana, The Dakotas, and Wyoming are among the driest places in this country in the summertime. So where all that water go?
It didn’t disappear in an instant. A plane didn’t crash into it. A bomb didn’t explode nearby. No one siphoned off a billion gallons and piped it south to our southwestern states. However, it did disappear.
My superficial research did not give me a good reason why the water is no longer there. I did learn that temperatures in that region used to be sub-tropical and that the water eventually “shrunk” or “retreated”. That’s about all I could find, but the fossil record and the geology of regions confirm that the water was there, and it supported a huge variety of life forms.
So could Lake Michigan – and all the Great Lakes –shrink, retreat or “permanently” disappear? Well, sure. Not today, and probably not soon, but eventually it might happen. If the Aral Sea in eastern Asia is used an example it CAN happen. I will write more about the Aral Sea another time, and how it has significantly shrunk in only one generation.
For today, I will be content knowing that tomorrow when the fog clears up Lake Michigan will be back in view. At least for this decade.
As an aside – something I learned along the way. When I goggled the Western Interior Seaway, one of the more informative websites was that of the U-Haul moving truck company. I thought it was a mistake, but the U Haul site has a section called Supergraphics. I am sure you have noticed those great pictures from different states that decorate the sides of their trucks. Well, their website not only has the graphics for each state and Canadian province, but good information including history, geology, botany, and more about each. In addition, you can buy tee shirts with those graphics on them, too. Pretty cool.
Check it out at http://www.uhaul.com/supergraphics