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Glacial ice map tells interesting history

February 23, 2013
By GARRY BRANDENBURG , Times-Republican

GLACIERS don't just happen without a cause. Likewise, they do not melt into retreat without powerful cosmic influences way beyond the scope of the average human being to understand. It will be impossible to condense in one short essay all the details of why glaciers develop and move under their own immense bulk only to be followed thousands of years later by the inevitable loss of ice as melting takes place. However, the history of Iowa is well documented by evidence left behind in the present day land forms of our state, glacial rocks left behind that fell out of glacial ice tongues, and river systems shaped by huge torrents of glacial melt water cutting through the land's surface. Iowa's geologic history tells us that at least eight or nine previous major glaciations impacted our landscape. It was and still is an on-going geologic experiment, only this time human beings are living during the present day inter-glacial warm period. Be glad we are living during the warmer times between glaciers. The alternative of trying to adjust and adapt to an impending advancing ice age is a case where there are way more losers than winners. But we can rest easy since any of the above scenarios take place on geologic time frames, far and away more lengthy than any human life span.

During this scribe's tenure at Iowa State University in the late 1960s, the big push at that time was a hypothesis that glaciers would grow and advance, a new coming ice age, and that the source of this imminent doom and gloom was man-kinds alteration of the environment. It was unwise to criticize this popular notion. And I, as an undergraduate student, assumed that people with PhD's knew more than I did. They had to be right, of course, so I went along with the theme ... for awhile. While the term politically correct was not in vogue like it is today, I soon learned that getting an education was my priority. Being indoctrinated by false premises, twisted science or going along with the 'in crowd' was leading to a dangerous path. Science had to rule. Hard facts had to rule. Agendas for political causes created a distinct smell in the air as if a drunk skunk just left a fermenting cabbage patch and was unable to hold its flatulence.

I soon found out, thankfully, that not all professors on campus subscribed to the doom and gloom diatribe. I'm glad that other views were discussed. A required course in propaganda analysis was a big hit with me. It taught a healthy skepticism for all sources of information until the truth could be obtained from many outside sources. When the truth was compared to an original story, the two were not at all the same. Time after time class assignments urged and required lots of comparison shopping and careful evaluation. Those lessons have stuck with me and I'm glad for it.

Article Photos

CONTRIBUTED PHOTO 
Today’s ice retreat map depicts the history of advance, retreat and re-advances of great ice sheets of North America. About 18,000 years ago, there were three distinct ice sectors with an interlocking system of ice divides. Between 18,000 and 13,000 years ago, the retreat (melting) was considered “slow” by geologists. A faster rate of retreat took place between 13,000 and 8,000 years ago as naturally warming climate forces were gaining strength. Over subsequent additional long periods of geologic time, the ice locked up in these former glacial fortresses submitted to almost complete melting. This map was developed by Canadian Geological Survey authors Arthur Dyke and Victor Prest in their publication titled Late Wisconsinan and Holocene History of the Laurentide Ice Sheet. It tells of the natural history of North America that shaped the land we live on today.

A few days ago, a big snow storm hit Iowa. It was nothing abnormal by any means, just another chapter in a very large book of how active weather systems roll with the punches. Heat from one air mass invades cold air, high pressure in one area moves toward low pressure in another. Caught in the mix are warm moist air masses and cold dry air. Stir thoroughly to form the ingredients for lots of rain, sleet or snow, all depending upon where one lives with respect to the storm path. But some supposed news sources claimed that these storms are examples of man-made climatic alterations. Not so. Weather is what happens in the short term. Climate is the very long term average over hundreds to thousands of years. Cause and effect have to be proven, not cherry picked and presented as fact to an uninformed public whose overall knowledge of science is dismal at best.

So what really drives the big swings in earth's natural history and its climatic variations? First, our sun, with its own phases of activity impulse increases and decreases intertwined with suns spot waxing and waning. Second is the orbit or our earth around the sun, going from almost circular to slightly elliptical and back again over a period of about 100,000 years. Third is the axial tilt of the earth with respect to its ecliptic plane that varies between 22.5 to 24.5 degrees on a 40,000 year cycle. This cycle has influence on the amount of solar insolation each hemisphere receives. And fourth is the wobble of the earths axis, called precession that fluctuates on an 19,000 to 20,000 year cycle. The combination of all the above were noted decades ago by Milutin Milankovitch, a Serbian mathematician, who connected the dots so to speak that there was a strong correlation of all the above with glacial advancing stages or interglacial warm periods. His hypothesis has been substantiated via geologic rock strata, deep ocean sediments and ice core analysis. These galactic forces are so huge in comparison to any man-made influences that it is kin to putting a thimble full of extra water into an Olympic sized swimming pool and expecting to be able to see a rise in the water.

Will our present interglacial warm time slowly fade toward the next glacial growth period? Yes. Will it take a long geologic time to occur? Yes. Will humans be around to see it? Not sure on this one. If we are, our choice is limited to adapting to those huge forces driving the change. To think we can spend enough money to alter that entirely natural galactic course of events is foolhardy. And we don't have to be a scientist or a pontificating politician to know how powerless humans are in this case.

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On the much more lighter side, have fun at the upcoming DUCKS UNLIMITED banquet and annual membership gathering on March 9. This year the event will move to the Impala Ballroom located on West Lincoln Way in Marshalltown. The Iowa River Chapter of DU event committee has been working hard to organize the evenings agenda of things to do, people to see, fun games to participate in and good food to eat. The auction will be just one part of the festivities. DU youth Greenwing program participants will be recognized. And at least 14 sporting guns for the waterfowler will be in the mix to bid on or win via raffle drawings. Tickets in advance are $45 and can be purchased by contacting Rich Naughton at 752-7197.

Wetland conservation is a good cause. The habitat found in wetlands is home to hundreds of species of non-game animals in addition to the few species of ducks or geese that waterfowl hunters enjoy pursuing. Wetlands are also a big cleaning station for water, taking runoff from the entire watershed and filtering it through aquatic plants and invertebrate organisms. Clean water is what finally exits these marshlands.

Wetlands are part of the natural landscape. In Iowa, a great quantity of shallow to deep water marshes were created by the action of advancing glacial ice. When it was time for the ice to melt, water sitting in depressions did not go away fast. Over time the potholes of the upper midwest proved to be ideal sites for birds, particularly ducks and geese. Fossil evidence of waterfowl species show that they adapted to the immense changes in the environment before, during and after glacial episodes. We have something to learn from them about improvising when times are tough.

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The March issue of the IOWA SPORTSMAN magazine has an interesting article starting on page 18. The editorial staff attempted to rank all 99 counties in Iowa based on eight categories. Included in the eight are (1) public land, (2) fishable waters, (3) variety of fish, (4) waterfowl opportunities, (5) deer harvest, (6) upland game, (7) turkey population, and (8) predator and small game species. Scores of 1 to 10 were given in each category, then added up for a final score. Allamakee County topped the list with a score of 61. Lots of fish varieties either in the Mississippi River or nearby trout streams helped. Great turkey and deer populations added good data. Marshall County came in at 65th place with a score of 35. Ida County was last place (99th) with a score of 19. Habitat availability varies greatly from some Iowa counties with rough terrain compared to highly agricultural places. Every county may have a few 'honey holes' but overall, this exercise fits well over a topographic map and land use map. The top ten counties in order are Allamakee, Clayton, Jackson, Appanoose, Lee, Dubuque, Dickinson, Linn, Marion and Muscatine. Read it over closely. This is a great little magazine to have, to read, and to enjoy.

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"Fishing should be contemplative rather than a competitive sport, except between friends." -The late Fenton Roskelley, outdoor writer for the Spokane Daily Chronicle.

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Garry Brandenburg is a graduate of Iowa State University with BS degree in Fish & Wildlife Biology. He is the retired director of the Marshall County Conservation Board. Contact him at PO Box 96, Albion, IA 50005.

 
 

 

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